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A-level Biology > 2 - Cells And Immune System > Flashcards

2 - Cells And Immune System Flashcards

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1
Q

Explain the Order of cell fractionation

A

1- chop up fresh liver tissue in ice cold buffer solution
2- put the chopped tissue into a blender or homogeniser which breaks open the cells
3- filter the mixture to remove the debris
4- pour the mixture into tubes and spin very quickly in a centrifuge. The Denser parts of the mixture get spun to the bottom of the tube where they form a pellet called the sediment
5- the liquid layer on top (the supernatant) is pored into a fresh tube leaving the sediment behind, thus contains the nuclei
6- this supernatant may then by spun again at a faster speed to produce a sediment containing mitochondria

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2
Q

What does the sediment in cell fractionation spun at a lower speed contain

A

Nuclei

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3
Q

What does the sediment in cell fractionation spun at a medium speed contain

A

Mitochondria

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4
Q

What does the sediment in cell fractionation spun at a higher speed contain

A

Ribosomes, membranes

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5
Q

What is the name of the liquid layer on top of the sediment in cell fractionation

A

Supernatant

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6
Q

Why does it have to be cold in cell fractionation

A

To stop enzymes activity which might break down organelles

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7
Q

Why does it have to be isotonic in cell fractionation

A

(Same Water potential)
To prevent organelles bursting / shrinking due to osmotic loss or gain

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8
Q

Why does it have to be buffered in cell fractionation

A

No PH function which may alter structure/functioning of enzymes/organelles

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9
Q

What type of lenses do microscopes use

A

Convex

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10
Q

What is light microscopes resolution

A

0.2 micrometers

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11
Q

What resolution does an electron microscope have

A

0.1 manometer

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12
Q

Why does electron microscopes have a higher resolution

A

They have a shorter wavelength

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13
Q

How to get from m to mm

A

X1000

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14
Q

How to get from mm to um

A

X1000

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15
Q

How to get from um to nm

A

X1000

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16
Q

Magnification equation

A

Magnification = size of image / size of object

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17
Q

What is resolution

A

The resolving power is the minimum distance apart the 2 objects can be in order for them to appear as separate items

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18
Q

What does a resolution depend on

A

The wavelength or form of radiation

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19
Q

What does greater resolution mean

A

The greatest clarity + more precise image

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20
Q

What can be seen with a light microscope

A

Mitochondria (maybe)
Nucleus

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21
Q

What is the maximum useful magnification of an optical microscope

A

X1500

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22
Q

What do electron microscope use to from an image

A

Electrons

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23
Q

What is the maximum useful magnification of an electron microscope

A

X 1 500 000

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24
Q

How do you temporarily mount a specimen on a slide

A

1) pippett a small amount of water onto a slide, then use tweezers to place a thin section of your specimen on top of the water drop

2) add a drop of stain (used to highlight objects in a cell)

3) add a cover slip - stand the slip upright on the slide next to the water droplet , then carefully tilt and lower - try not to get any air bubbles

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25
Q

Why do you have to be carful not to get any airbubbles under you cover slip when using a microscope

A

They will obstruct a view of the specimen

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26
Q

When using microscopes- what is the dye eosin used to make show up

A

Cytoplasm

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27
Q

When using microscopes- what is the dye iodine in potassium iodide solution used to make show up

A

Starch grain in plant cells

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28
Q

In cell fractionation why does the cell need to be put in a blender

A

To break up the plasma membrane and release the organelles into the solution

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29
Q

Why does the homogenised cell solution need to be filtered (cell fractionation)

A

To separate any large cell debris or tissue debris (like connective tissue, from the other organelles)

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30
Q

What order to the organelles in animal cells become pellets during cell fractionation

A

Nuclei
Mitochondria
Lysosomes
Endoplasmic reticulum
Ribosomes

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31
Q

In a plant cell, when do the chloroplasts come out in cell fractionation

A

After nuclei but before mitrocondria

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32
Q

How to draw specimens

A

Pencil
No shading / colouring (only draw the lines you can see)
Each field of view (circular diagram) should be about 3rd of a page in size
If the cells you are viewing are similar / repeatable it’s useful to draw about 4-5 only

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33
Q

What must you always record when drawring specimens form a microscope

A

Magnification
Name of specimen
Date of observation

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34
Q

What equipment do you need to use to a cell size of an unknown

A

Stage micrometer
Eye piece graticule

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35
Q

What is a stage micrometer

A

A precise rule on a slide

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36
Q

How to calculate the cell size of an unknown

A

1) calibrate - focus the stage micrometer under a low pressure - this must be done for each magnification (objective lens)
2) work our how many eye peice divisions equal every stage division
3) remove the stage micrometer + place slide containing cells under microscope + count the number of eyepiece divisions under one microscope

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37
Q

What are TEMS

A

Transmission electron microscopes

Use electromagnets to focus a beam of electrons, which is then transmitted through the specimen

Denser parts of the specimen absorb more more electrons, which makes them look darker on the image you end up with.

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38
Q

Positive of TEMS

A

High resolution image
You can see internal structures and organelles like chloroplasts

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39
Q

Negatives of TEMS

A

They can only be used on thin specimens

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40
Q

What are SEMS

A

Scanning electron microscopes

Scan a beam of electrons across the specimen. This knocks off electrons from the specimen, which are gathered in a cathode ray tube to form an image

The image you end up with show the surface of the specimen and they can be 3D

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41
Q

Postives of SEMs

A

Can be used on thick specimens

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42
Q

Negatives of SEMS

A

Lower resolution image than TEMS

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43
Q

What are the 2 types of electron microscopes

A

Scanning
Transmission

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44
Q

Principles of using an electron microsope

A

Vacuum
Non living - smallest sample
Thin
Complex staining / preparation (have to be trained to use)
Image contains ‘artefacts’

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45
Q

Is a TEM or a SEM 3D

A

SEM - 3D
TEM - 2d

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46
Q

What is the result of using an electron microscope

A

Photomicrograph

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47
Q

Limitations of an electron microscope

A
  • electron beams may destroy sample
  • preparation difficulties lead to revolution problems
  • photomicrograph is in ‘false colour’
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48
Q

Resolution of a TEM

A

0.1 nm

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49
Q

Resolution of a SEM

A

20nm

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50
Q

What does the cyto skeleton consist of

A

A network of fibres necessary for the shape and stability of the cell
- microfilaments
- microtubules
- intermediate fibres

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51
Q

What is in the cell surface membrane

A
  • embedded proteins - involved in signalling + communication between cells
  • others act as antigens for ‘self’ and foreign recognition
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52
Q

What is the cell wall made of in plants + fungi

A

Plants - cellulose

Fungi - chitin

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53
Q

What is the cell wall

A

A complex carbohydrate - freely permeable. It gives shape to cell + allows the cells content to push against it making it rigid

It acts as a defence mechanism protecting against invading pathogens

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54
Q

What is the vacuole

A

Membrane lined sac filled with cell sap
Large + permanent Maintaining turgor against the cell wall

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55
Q

What is the membrane of the vacuole called

A

The tonoplast
It’s selectively permeable ( some molecules can pass through but some can’t)

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56
Q

What is the role of chloroplasts

A

Carry out photosynthesis

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57
Q

What shape and size are chloroplast

A

Vary in shape but are typically disk shape
2-10um long and 1um in diameter

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58
Q

What are the 3 main features of a chloroplast

A

The chloroplast envelope

The grana

The stroma

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59
Q

What is the chloroplast envelope

A

Double plasma membrane surrounding the organelle- highly selective in what is allowed to enter and leave

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60
Q

What is the grana in chloroplasts

A

Stacks of up to 100 disc like structures called thylakoids
- some thylakoids have tubular extensions that join up with other thylakoids in adjacent grana
-

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61
Q

What happens in the grana

A

Where the first stage of photosynthesis (light absorption) takes place

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62
Q

What is within in thylakoids

A

Chlorophyll

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63
Q

What is the stroma

A

A fluid filled Matrix
Within the stroma are a number of other structures (eg, starch grains)

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64
Q

What process takes place in the stroma

A

Second stage of photosynthesis
(Synthesis of sugars)

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65
Q

How have chloroplasts adapted to their function of harvesting sunlight and carrying out photosynthesis

A

-Granal membrane - large surface membrane for attachment of chlorophyll, electron carriers and enzymes that carry out the first stage of photosynthesis - these chemicals are attached to the membrane in a highly ordered way.

  • the fluid of the stroma possesses all the enzymes needed to make sugars in stage 2 of photosynthesis.
  • chloroplasts contain DNA + ribosomes so can quickly + easily manufacture some proteins needed for photosynthesis
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66
Q

What is the nucleus

A

Large organelle surrounded by a nuclear envelope (double membrane), which contain many pores. The nucleus contains chromosomes (which are made form protein-bound linear DNA)
And another structure called nucleoles

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67
Q

What is the function of the nucleus

A
  • controls cell activity (by controlling transcription of DNA) DNA contains instructions to make proteins.
  • pores allows substances to move between the nucleus and the cytoplasm, the nucleolus makes ribosomes
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68
Q

Describe the mitochondrion

A

Usually oval shape - double membrane, inner in is folded to form Cristae. Inside is the matrix, which contains enzymes involved in respiration

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69
Q

What is the function of mitochondria

A

The site of aerobic respiration, where ATP is produced. Found in large numbers in cells that are very active and require a lot of energy

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70
Q

Describe Golgi apparatus

A

A group of fluid filled, membrane bound flatterend sacs.
Vesicles are oftern seen at the edge of sacs

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71
Q

Function of Golgi apparatus

A

It processes and packages new lipids and proteins.
It also makes lysosomes

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72
Q

Describe Golgi vesicles

A

A small fluid filled sac in the cytoplasm, surrounded by a membrane and produced by the Golgi apparatus

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73
Q

Function of Golgi vesicle

A

Stores lipids and proteins made by the Golgi apparatus and transports them out of the cell (via the cell surface membrane)

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74
Q

Describe lysosomes

A

A round organelle surrounded by a membrane, with no clear internal structure. It’d a type of Golgi vesicle

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75
Q

Function of lysosomes

A

Contains digestive enzymes called lysozymes.
These are kept separate form the cytoplasm by the surrounding membrane, and can be used to digest invading cells or to break down work out components of the cell.

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76
Q

Describe
Rough endoplasmic reticulum

A

A system of membrane enclosing a fluid filled space.
The surface is covered with ribosomes

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77
Q

Function of rough endoplasmic reticulum

A

Folds and processed proteins that have been made at the ribosomes

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78
Q

Describe smooth endoplasmic reticulum

A

Similar to RER - but no ribosomes

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79
Q

Function or smooth endoplasmic reticulum

A

Synthesises and processes lipids

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80
Q

Function of ribosome

A

The site where proteins are made

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81
Q

Describe ribosomes

A

Very small organelle thar either floats freely on the cytoplasm or is attached to the RER. It’s made of proteins and RNA. It’s not surrounded by a membrane

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82
Q

What is the structure of centrioles

A

Small protein tubes if microtubules

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83
Q

Function of centrioles

A

Form fibres in cell division known as spindles which separate chromosomes

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84
Q

What is cell differentiation

A

The process by which cells become specialised for differnt functions

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85
Q

Why do cells act and look differently

A

Different genes are switched on and off in each of the specialised cells

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86
Q

What is a tissue
+ examples

A

A collection of cells (not necessarily identical ones) that preforms a specific function

Eg. Epithelial tissue, muscles, nervous, connective

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87
Q

What is an organ

A

A combination of tissue that are coordinated to preform a variety of functions

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88
Q

What size ribosomes do eukaryotic cells have

A

Large (70s)

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89
Q

What size ribosomes do prokaryotic cells have

A

Small

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90
Q

Where is dna held and located in eukaryotic cells

A

In the nucleus on linear chromosomes

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91
Q

Where is dna held and located in prokaryotic cells

A

Contained within the cytoplasm held on circular DNA

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92
Q

What is the cell wall made of in eukaryotic cells if present

A

Cellulose

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93
Q

What is the cell wall made of in prokaryotic cells

A

Peptidoglycan

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94
Q

Eukaryotic or prokaryotic
Has membrane bound organisms

A

Eukaryotic

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95
Q

Eukaryotic or prokaryotic
May have a unduipodia

A

Eukaryotic

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96
Q

Eukaryotic or prokaryotic
May have flagella

A

Prokaryotic

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97
Q

Eukaryotic or prokaryotic
Has a nucleus

A

Eukaryotic

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98
Q

Eukaryotic or prokaryotic
Has a phospholipid bilayer cell membrane

A

Eukaryotic

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99
Q

Eukaryotic or prokaryotic
Ribosomes are the site of protein synthesis

A

Prokaryotic

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100
Q

What can first
Eukaryotic or prokaryotic

A

Prokaryotes

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101
Q

Describe prokaryotes

A

They have nucleic acids but not confined to a nucleus with a nuclear membrane

They don’t have mitrochondia and have smaller ribosomes

Many have flagellum

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102
Q

Size of bacteria

A

0.1 - 1.0 um

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103
Q

What is the cell wall made of in bacteria

A

Muriel (polysacccharide + peptides)

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104
Q

T or f
Many bacteria have a mucilaginous sli,e late r

A

T

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105
Q

How does bacteria store food

A

Oils and glycogen droplets

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106
Q

What is the significance of a virus being unliving

A

replicated only inside living cells of other organisms

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107
Q

Describe the basic structure of a generalised virus

A

Generic material (DNA + RNA)on a protein coat ( capsid), some have an envelope. Have glycoprotein receptor spikes on the envelopes

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108
Q

Describe the purpose of the glycoprotein spikes

A

Attach to surface of the host cell they’re infecting

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109
Q

Describe the purpose of a bacteriophages tail fibres

A

Help it to attach to host cells

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110
Q

T or f
Viruses are not organisms

A

T

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111
Q

How do viruses live

A

Using materials from living cells

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112
Q

Size of viruses

A

20 - 300nm in size

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113
Q

What genetic material do viruses have

A

DNA or RNA

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114
Q

Where is the genetic material in viruses

A

Encased in capsid, which may have attachment proteins (protein coat) some have a lipid envelope

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115
Q

What is in a cellulose cell wall of a plant cell

A

Plasmodesmata
(Channels for exchanging substances with adjacent cells)

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116
Q

What do plants use starch grains for

A

To store excess sugars

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117
Q

What are algal alike

A

Plant cells
They have the same organelles including cell wall app and chloroplasts

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118
Q

What are fungal cells a lot alike

A

Plant cells

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119
Q

What are the two key differences between fungal cells and plant cells

A
  • their cells walls are made of chitin not cellulose
  • they don’t have chloroplasts because they don’t photosynthesise
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120
Q

How have epithelial cells in the small intestines specialised to absorb food efficiently

A

1) the walls of the small intestines have lots of finger like projections called villi, these increase surface area for absorption
2) the epithelial cells on the surface of the villi have folds in their cell- surface membrane, called microvilli. These inc the surface area even more
3) they have lots of mitochondria to provide energy for the transportation of digested food molecules into the cells

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121
Q

In multicellular eukaryotic organisms, specialised cells are grouped together to form?

A

Tissues

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122
Q

Does the cytoplasm of a prokaryotic cell have membrane bound organelles

A

No

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123
Q

What is the plasma membrane mainly made of in a prokaryotic cell

A

Lipids and proteins

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124
Q

What does the cell wall do in prokaryotic cells

A

Supports the cell and prevents it from changing shape.

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125
Q

What is the cell wall made from in prokaryotic cells

A

A polymer called murein
Murein is a glycoprotein

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126
Q

What is a glycoprotein

A

A protein with a carbohydrate attached to it

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127
Q

What do some prokaryotes inc bacteria have that’s made up of secreted slime

A

Capsule

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128
Q

What does the capsule do in prokaryotic cells

A

Helps to protect bacteria from attach by cells of the immune system

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129
Q

What are plasmids

A

Small loops of DNA
They arnt part of the main circular DNA molecule.
Plasmids contain genes for things like antibiotic resistance, and can be passed between prokaryotes. Plasmids are not always present in prokaryotic cells.
Some prokaryotic cells have several

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130
Q

Where is the DNA in prokaryotic cells

A

Floats free in the cytoplasm
It’s circular DNA, presents as one long coiled up strand
It’s not attached to any histone proteins

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131
Q

What is the flagellum

A

It’s a long, hair like structure that rotates to make the prokaryotic cell move. Ot all prokaryotes have a flagellum some have more than one

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132
Q

What does it mean than viruses are acellular

A

They are not cells

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133
Q

What are viruses

A

Nucleus acids surrounded by proteins - there not alive

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134
Q

What’s smaller bacteria or viruses

A

Viruses

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135
Q

What do bacteria have that viruses done

A

Plasma membrane
Cytoplasm
Ribosomes

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136
Q

How do viruses reproduce

A

They invade and reproduce inside cells of other organisms,s
These are known as host cells

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137
Q

Describe a viruses structure

A

Contains a core of genetic material - either DNA or RNA
The protein coat around the core is called the capsid
Attachment proteins stick out fro, the edge of the capsid, these let the virus cling on to a host cell

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138
Q

How do prokaryotic cells replicate

A

By binary fission

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139
Q

Explain binary fission

A

1) the circular DNA and plasmids replicate. The main DNA loop is only replicated once but plasmids can be replicated loads of times
2) the cell gets bigger and the DNA loop move to opposite poles of the cell
3) the cytoplasm begins to divide( amd re cell walls begin to from)
4) the cytoplasm divides and two daughter cells are produced. Each daughter cell has one copy of the circular DNA, but can have a variable number of copies of the plasmids

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140
Q

How do viruses use host cells to replicate themselves

A

Viruses use their attachment proteins to bind to complementary receptor proteins on the surface of host cells

Differnt viruses have differnt attachment proteins and therefore require differnt receptor proteins on host cells. As a result some viruses can only infect one type of cell ( others can infect lots of differnt cells)

Because they are not allibe viruses don’t undergo cell division. Instead they inject their DNA or RNA into host cell - thus hijacked cell they uses Ito own ‘machinery’ to do the viruses work and replicate the viral partials

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141
Q

What are the 3 main important features of mitosis

A

Growth ( from zygote to embryo to human)

Differentiation ( cells become specialised from stem cells + genes start to tell cells what to do )

Repair ( to repair and replace damages tissue)

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142
Q

Explain replication in virsuses

A

Viruses are non living so they attach to their host cell with attachment proteins on their surface
They inject their nucleic acids into the host cell
The genetic information on injected boreal nucleic acid provided instruction for the host cell to start producing viral components eg. Enzymes, nucleic acid

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143
Q

Explain how a virus invades a cell

A

1) a virus enters a cell
2) substances in the cell begin to strip off the viruses outer coat of proteins
3). Nucleic acids in the virus is released
4) nucleic acid get into cells chemical manufacturing system
5) the cell ‘ignors’ it’s own chemical needs + switched to making new viruses
6) the cell is sometimes destroyed in the process - many of the new viruses are released to infect other cells

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144
Q

How often does mitosis occur

A

Every 24 hours

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145
Q

What is mitosis

A

The division of the nucleus to make an exact cope of the DNA in a parent cell

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146
Q

Are daughter cells always identical to their parent cells in mitosis

A

Most of the time
Apart from extremely rare cases of mutations

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147
Q

What is the phase before mitosis occurs called

A

Interphase

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148
Q

What happens in prophase

A

chromosomes become shorter and fatter each one consisting of a pair of identical chromatids joined at the centromere
Tiny bundles of proteins called centrioles start moving to opposite ends of the cell forming a network of protein fibres across it called spindle.
Nucleolus shrinks and eventually disappears
Nuclear envelope breaks down and chromosomes lie free in the cytoplasm

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149
Q

What happens in metapahase

A

Chromosomes arrange themselves on the equator of the spindle but not in homologous pairs

Chromosomes appear attached to the spindle at their centromeres

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150
Q

What happens in anaphase

A

Centromere splits into two each centromere having its own chromatid

Spindle fibres contract and pull the chromatids apart centromere first - this makes chromatids appear v-shaped

Chromatids now become chromosomes with their centromere leading

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151
Q

What happens in telophase

A

Chromatids reach the opposite poles of the cell at the centrioles - they uncoil and become long and thin again. They are now called chromosomes again

Nuclear envelope + nucleolus reform - so now two nuclei

Spindle fibres degenerate

Chromosomes develop into thread lines structure of chromatin

Centrioles replicate

Cytokinesis follows this phase
Cytoplasm divides (cytokinesis) and there are no two genetically identical daughter cells

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152
Q

What are the 4 stages of mitosis

A

Prophase
Metaphase
Anaphase
Telophase

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153
Q

What is the phase interphase divided into

A

3 separate growth staged
G1
S
G2

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154
Q

What happens in G1 of interphase

A

Cell grows and new organelles and proteins are mad e

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155
Q

What happens in S of interphase

A

Cell replicated its DNA ready to divide by mitosis

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156
Q

What happens in G2 (gap phase 2) of interphase

A

Cell keeps growing and proteins needed for cell division are made

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157
Q

Describe interphase

A

The cell carries out normal functions, but also prepares to divide .
The cells DNA is unravelled and replicated to double its genetic content. The organelles are also replicated so it has spare ones and it’s ATP content is increase ( atp provides the energy needed for cell division)

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158
Q

What is mitosis and the cell cycle controlled by

A

Genes

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159
Q

Normally when cells have divided enough times to make enough nrew cells they stop.
How does this change if there is a mutation in a gene that controls cell division

A

The cell can grow out of control
The cells keep pm dividing to make more and more cells wich form a tumour
Cancer is a tumour that invades surrounding tissue

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160
Q

How are some, treatments for cancer designed to control the rate of cell division

A

By disrupting the cell cycle
This kills the tumour cells

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161
Q

Why is cancer treatment that disrupts cell cycle bad

A

The treatment doesn’t distinguish between tumour cells and normal cells
They kill normal body cells that are diving.
However tumour cells divide more frequently than normal so the treatment is more likely to kill tumour cells.

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162
Q

Examples of cancer treatment that disrupted the G1 phase

A

Chemotherapy prevents the synthesis of enzymes needed for DNA replication. If these arnt produced, the cell is unable to enter the synthesis phase(s) disrupting the cell cycle and forcing the cell to kill itself

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163
Q

Examples of cancer treatment that disrupted the S phase

A

Radiation and some drugs damage DNA. At several points in the cell cycle the DNA in the cell is checked for damage. If damage is detected the cell will kill itself - preventing further tumour growth

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164
Q

Explain how you can prepare a root Tip to observe mitsosis

A

1) cut 1cm from the top form a growing root.
2) prepare a boiling tube containing 1M hcl acid and put it in a water bath at 60°C
3) transfer the root tip into the boiling tub and incubate for 5 mins
4) using a pipette rinse the root tip with cold water and leave to dry on a paper towel

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165
Q

When observing mitosis experiment, why does it need to be the tip

A

That’s where the growth occurs so it’s where mitosis takes place

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166
Q

How would u use the prepared root tip to observe mitosis

A

1) place root tip on microscope slide and cut 2mm from the very top. Get rid of the rest
2) use a mounted needle to break the top open and spread the cells out thinly
3( add a few drops of stain and leave for a few min
4) place a cover slip over the cells and push down firmly to squash the tissue.
5) now you can see mitosis under an optical microscope

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167
Q

Why do u add stain when observing mitosis
+ examples of stain

A

Makes the chromosomes easier to see.
Toluidide blue O, ethano-orcein, feulgen

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168
Q

Why do u neeed to push the cover slip down firmly when obeserving mitosis s

A

It will make the tissue thinner and allow light to pass through.
But you can’t smear rhe cover slip sideways as you will damage the chromosomes

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169
Q

How do u use an optical microscope to observe the prepared root tip

A

1) start by clipping the solid onto the stage
2) select lowest powered objective lense
3) use coarse adjustment knob to bring the stage up to just below the objective lense
4) look down the eyepiece (which contains the ocular lense), use coarse adjustment knob to move stage downward away from the objective lens until the image is in focus
5) adjust focus with th e fine adjustment knob, until you get a clear image of what’s on the slide
6) you can then swap to an higher powered objective lense if you need greater magnification

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170
Q

What is mitotic index

A

The proportion of cells undergoing mitosis

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171
Q

How do you calculate mitotic index

A

Number of cells with visible chromosomes
____________________________________________
Total number of cells observed

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172
Q

What is an eyepiece graticule and where is it fitted

A

A transparent ruler with numbers but no units
Onto the eyepiece

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173
Q

What is a stage micrometer rand where is it placed

A

A microscope slide with an accurate scale with units and is used to work out the value of division on the eyepiece graticule at a particular magnification
On the stag e

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174
Q

What are artefacts

A

Things that you can see down the microscope that arnt part of the cell or specimen that your looking at
Eg, dust , airbubbles and fingerprints, inaccuracies caused by squashing and staining your sample

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175
Q

When are artefacts most commen

A

In electron micrograph because the specimens need lots of preparation.

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176
Q

At first how could scientists distinguish between artefacts and organelles

A

By repeatedly preparing specimens in differnt ways.
If it can be seen in one preparation but not another it if most likely and aryifact

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177
Q

What is diffusion

A

The tendency of a gas/liquid to spread out from a high conc. to a low conc. till it reaches equilibrium
(Net movement of particles from high to low conc.)

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178
Q

T or f
Simple diffusion is active

A

F
It’s passive

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179
Q

Describe the elements of simple diffusion

A

Passive
Motion is random and constant
Particles bounce of each other + the vessel
All particles will distribute themselves evenly as a result of diffusion

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180
Q

What is ficks law

A

Diffusion is proportional to the difference in conc between two regions (the conc gradient)
It’s incorrect to say diffusion is proportional to conc

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181
Q

What are some factors that affect rate of diffusion

A

Temperature
Conc. gradient
Stirring / moving
Surface area (eg, alveoli / villi)
Distance / thickness (short diffusion pathway)
Size of molecule ( Small diffuse fastest)

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182
Q

Is substances are insoluble in ……, they cannot easily cross the mebrane
What do they use?

A

Lipids
They use transport proteins and transport water soluble substances that are insoluble in lipids

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183
Q

What is facilitated diffusion used for

A

Large polar molecules. Eg. Glucose and amino acids
Charged ions

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184
Q

Is facilitated diffusion passive or active

A

Passive
But molecules use proteins instead of passive between the phospholipids

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185
Q

What are the 2 types of proteins in facilitated diffusion

A

Carrier proteins
Channel proteins

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186
Q

What is a protein channel

A

Pores in membrane
Many only let 1 type of molecule through
There water filled hydrophilic channels

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187
Q

What is a carrier proteins

A

Molecules fit in at membrane
Proteins change shape to pass molecules through

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188
Q

What surrounds cells

A

Cell surface membrane

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189
Q

What is a the cell surface membrane

A

The barrier between the cell and its environment controlling which substances enter and leave the cell.
There partially permeable.

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190
Q

What does partially permeable mean

A

They let some molecules through but not others

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191
Q

How can substances move across the cell surface membrane

A

By diffusion
Osmosis
Active transport

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192
Q

What do membranes around organelles do

A

They act as a barrier between the organelle and the cytoplasm
They are also partially permeable

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193
Q

When was the fluid mosaic model suggested

A

1972

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194
Q

Describe the fluid mosaic model

A

Phospholipid molecules form a continuous double layer (bilayer)
The bilayer is fluid because the phospholipids are constantly moving
Cholesterol molecules are present within the bilayer
Protein scattered through the bilayer like tiles in a mosaic, these include channel proteins and carrier proteins which allow large molecules and ions to pass through the membrane. Receptor proteins on the cell surface membrane. Allow the cell to detect chemicals release from other cells. The chemicals signal to the cell to respond in some way.
some proteins are able to move sideways through the bilayer, while others are fixed in position
.

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195
Q

It cell membrane, some proteins have a polysaccharide chain attached. What are these called?

A

Glycol proteins

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196
Q

Some lipids in cell membranes have polysaccharide chain attached. What are these called?

A

Glycolipids

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197
Q

What do channel proteins and carrier proteins allow through

A

Large molecules and ions

198
Q

What is rhe head of a phospholipid (in terms of water).

A

Phospholipid head is hydrophilic (attracts water)

199
Q

What is rhe tail of a phospholipid (in terms of water)

A

Hydrophobic (repels water).

200
Q

How do phospholipids arrange themselves in the cell surface membrane

A

Into a bilayer
Head face out towards water on either side of membrane

201
Q

Why doesn’t the mebrane allow water soluble substances (like ions) through

A

It acts as a barrier to these dissolves substances
As the centre of the bilayer is hydrophobic

202
Q

T or f
Cholesterol is a type of lipid

A

T

203
Q

Is cholesterol present in all cell membranes

A

No
In all except bacterial cell membranes

204
Q

Where are cholesterol in the cell membrane

A

Fit between the phospholipids

205
Q

What does cholesterol do in the cell membrane + how

A

They bind to the hydrophobic tail of the phospholipids , causing them to pack more closley together
This restricts movement of the phospholipids, making the membrane less fluid and more rigid

It helps maintain the shape of animal cells, this is particle important for cells that Arnt supported by other cells (eg, red blood cells)

206
Q

Learn the cell membrane permeability practical

A

Page 37

207
Q

What is permeability of cell mebrane is affected by

A

Temp
Solvent conc

208
Q

Describe the permeability of phospholipids in membranes at temps bellow 0°c

A

They don’t have much energy, so they can’t move very much
They are very closley packed together and the memebrane is rigid
But channel proteins and carrier proteins in the memebrane deform, increasing the permeability of the membrane
ice crystals may form and pierce the membrane making it highly permeable when it thaws

209
Q

Describe the permeability of phospholipids in membranes at temps between 0 and 45 °c

A

The phospholipid can move around and aren’t packed tightly together. The membrane is partially permeable. As the temperature increases the phospholipids move more because they have more energy - this increases the permeability of the memebrane

210
Q

Why does increasing conc. of solvent increases permeability of cell membrane

A

The solvent dissolves the lipids in the cell membrane causing it to lose its structure

211
Q

Do molecules diffuse both ways

A

Yes
But the net movement will be to an area of lower concentration

212
Q

What is the concentration gradient

A

The path from an area of higher concentration to an area of lower conc. Particles diffuse down a concentration gradient

213
Q

Can particles diffuse across cell membranes

A

Yes, as long as they can move freely through the membrane

214
Q

What is it called when molecules diffuse directly through a cell membrane

A

Simple diffusion

215
Q

What’s wrong with larger molecules simply diffusing across the cell membrane

A

There so big it would diffuse very slowly through the phospholipid belayer

216
Q

What’s wrong with charged particles simply diffusing across the cell membrane

A

They would diffuse slowly, as Ther’re water soluble and the centre of the bilayer is hydrophobic

217
Q

How do charged particles and large particles diffuse through the cell membrane

A

Through carrier proteins or channel proteins

218
Q

What is facilitated diffusion

A

Particles use channel proteins and carrier proteins to move down a concentration gradient I from a higher to a lower concentration

219
Q

Is facilitated diffusion passive or active

A

Passive

220
Q

What do carrier proteins do

A

Move large molecules across membranes, down their conc. Gradient

221
Q

Do au carrier molecules facilitate the diffusion of all molecules

A

No, different carrier proteins facilitate different molecule

222
Q

How do carrier proteins work

A

1) a large molecule attached to a carrier protein in the membrane
2) then the protein changes shape
3) this releases the molecule on the opposite sides of the membrane

223
Q

What are channel proteins for

A

Charged particles

224
Q

What are channel proteins

A

Pores in the membrane

225
Q

What does rate off simple diffusion depend on

A

Conc, gradient
Thickness of exchange surface
Surface area

226
Q

H_ow does concentration graclient effect rate of simple diffusion

A

The higher the faster the rate, as diffusion takes place the difference in conc. Between the two sides of the membrane decreases until it reaches an equilibrium, this means that diffusion slows down over time

227
Q

H_ow does thickness of the exchange surface effect rate of simple diffusion

A

The thinner the exchange surface the faster the rate of diffusion

228
Q

How does surface area effect rate of simple diffusion

A

The larger the surface area the faster the rate of diffusion

229
Q

What do some cells have that increase surface area for faster diffusion

A

Microvilli

230
Q

What are microvilli

A

Projections formed by the cell-surface membrane by folding up on itself

231
Q

In human cells how much can microvilli increase the surface area

A

By about 600 times

232
Q

What effects rate of facilitated diffusion

A

The concentration gradient
The number of channel or carrier proteins

233
Q

What are aquaporins

A

Special channel proteins that allow the facilitated diffusion of water through cell membranes they allow cells to reabsorb a lot oj water in the kidneys that would otherwise be excreted by the body, about 180 liters need re-absorbing every day.

234
Q

Why can water diffuse directly through the membrane eventhough it’s polar

A

As its relatively small

235
Q

What is active transport

A

Movement of molecules or ions into or out of a cell from a region of low concentration to a region of high concentration using ATP and carrier molecules.

236
Q

Why is ATP needed in active transport

A

As materials move against the conc. gradient carrier proteins act as pumps involved in the process
It is very selective- and only avows certain substances across

237
Q

How is ATP used in active transport

A

By using ATP directly to move molecules
By using a conc. Gradient which is already set up by direct active transport (co - transport)

238
Q

Describe single molecule direct active transport

A
  • Molecules binds to receptors or channel or carrier proteins
  • on the inside ATP binds to proteins causing split to ADP +pi. This makes the protein molecule change shape and open on me opposite side of the membrane -
  • molecule is released on the other side of the membrane
  • p molecule released from protein and recombines with ADP to make ATP
  • this causes the protein to revert to its original shape
239
Q

What type of reaction is ATP → ADP + pi

A

Hydrolysis

240
Q

Describe bulk transport

A

Enzymes, hormones and Who cells are two large to fit through carrier proteins so there movea in and out of cells by bulk transport

241
Q

What is endocytosis

A

??.???””? Check
(Taken in)
This is bulk transport into cells by eg. Phagocytosis and pinocytosis
The cell membrane invaginates forming vesicles these are then moved into the cytoplasmfor further processing

242
Q

What is exocytosis

A

Reverse of endocytosis with vesicles being formed by the Golgi apparatus and released outside cells

243
Q

Energy in the form of ATP is required for the movement of vesicles along the ——- and for changing shape of cells to —–
What else is ATP required for

A

Cytoskeleton
Engulf materials

Th fusion of vesicles with cell membranes

244
Q

Examples of ATP use for movement in cells

A

Muscle cels _ helps them contract to allow movement

245
Q

Examples of ATP use for exocytosis

A

Goblet ceus- secretes mucus

246
Q

Examples of ATP use in endocytosis

A

Phagocyte - ATP used to change shape to engulf pathogens

247
Q

Example of use of ATP in single molecules direct active transport

A

Root hair cells - carrier proteins to take up molecules in the soil against conc. Gradient

248
Q

What are the 4 types of active transport

A

Exocytosis
Endocytosis
Single molecule transport
Co-transport

249
Q

Where does active transport only take place + why?

A

In living respiring cells
As active transport links to respiration

250
Q

What is the rate of active transport effected by

A

Temp.
Oxygen conc.

251
Q

Evidence for active transport

A
  • The rate of AT is affected by temp and oxygen conc.
    These both affect the rate of respiration and therefore the production of ATP

Many cells known to carry out a lot of active transport contain large number of mitochondria

Poisons which stop respiration or prevents ATPase from working also stop active transport. Eg. Cyanide inhibits ATP production so it stops active transport. However if ATP is added artificially transport starts again

252
Q

What proteins are involved in active transport

A

Carrier proteins

253
Q

What are the two main differences between active transport and facilitated diffusion

A

1) active transport usually moves solutes from a low to a high concentration
(In facilitated diffusion, they always move from a high to a low concentration)

2) active transport requires energy - facilitated diffusion does not

254
Q

Where does energy for active transport come from

A

1) ATP is a common source of energy in the cell. It’s produced by respiration
2) ATP undergoes a hydrolysis reaction, splitting into ADP and Pi. This releases energy so that the solutes can be transported

255
Q

What are co-transporters a type of

A

Carrier protein

256
Q

How do co-transporters work

A

1) they bind two molecules at a time
2) the concentration gradient of one of the molecules is used to move one other molecule against its own concentration gradient.

257
Q

Does a decreasing concentration gradient affect rate of active transport.

A

No. Molecules and ions move against their concentration gradient so a decreasing concentration gradient doesn’t affect the rate of active transport

258
Q

What is active transport affected by

A

1) the speed of individual carrier proteins - the faster they work the faster the rate of active transport
2) the number of carrier proteins present-the more proteins there are, the faster the rate of active transport
3) the rate of respiration in the cell and the availability of ATP. If respiration is inhibited, active transport can’t take place.

259
Q

How is glucose absorbed form the lumen of the ileum and why

A

By co-transportation

In the ileum the concentration of the glucose is too low for glucose to diffuse out of the blood

260
Q

Describe now glucose enters the ileum epithelium with sodium ions.

A

1) sodium ions are actively transported out of the ileum epithelial cells into the blood, by the sodium potassium pump. This creates a concentration gradient., there’s now a higher concentration of sodium ions in the lumen of the ilium, then outside the cell
2) this causes sodium ions to diffuse from the lumen of the ilium into the epithelial cells down their concentration gradient. They do this via the sodium glucose co-transporter proteins.
3) The co-transporter carries glucose into the cells with the sodium. As a result, the concentration of glucose inside the cell increases.
4) glucose diffuses out of the cell into the blood down its concentration gradient through a protein channel by facilitated diffusion

261
Q

What is osmosis

A

The passage of water from a region where it has high water potential ( dilute) to lower water potential (concentrated) over a partially permeable membrane.

262
Q

What will happen to the water potential if you add a solute

A

Lower the water potential

263
Q

What number must the water potential of a solution be less that

A

0

264
Q

The more conc. a solution the more ……. The water potential

A

Negative

265
Q

What would happen if animal cells were placed in pure water

A

Animal cells have solutes in their cytoplasm.
If placed in pure water - water would move in causing cells to burst
(Eg, haemolysis in red blood cells)

266
Q

How do animal cells prevent cells from taking in too much water and bursting

A

Animal cells are bathed in a liquid which has the same water potential
(Eg. Blood plasma in humans)

267
Q

What is water potential

A

Potential o water molecules to diffuse out of or into a solution

268
Q

What has the highest water potential

A

Pure water

269
Q

If two solutions have the same water potential, what are they said tobe

A

Isotonic

270
Q

What affect the rate of osmosis

A

1) the water potential gradient
2) the thickness ofthe exchange surface
3) the surface area of the exchange surface

271
Q

How does water potential gradient affect osmosis

A

The higher the water potential gradient the faster the rate of osmosis. As osmosis takes place the differnce in water potential on either side of the mebrane decreases, so the rate of osmosis levels of

272
Q

How does the thickness of the exchange surface effect osmosis

A

The thinner the exchange surface rhe faster the rate of osmosis

273
Q

How does the surface area of the exchange surface effect osmosis

A

The larger the surface area, the faster the rate of osmosis

274
Q

How to carry out the experiment to investigate water potential using serial dilution

A
  • Fill in later
275
Q

How do you do the practical :
Production of a dilution series of a solute to produce a calibration curve with which to identify the water potential of plant tissue

A

1) label 6 boiling tubes 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0 mol dm-3
2) use the 1.0moldm-3sucrose solution and water to make up 20cm3 of each concentration (using a pipette)
3) stand the boiling tubes donating the sucrose solution in a test tube rack at a constant temperature
4) using a potato chip cutter. Cut 6 chips from one potato tuber, remove any peel, using a ruler, scalpel and tile cut all chips to the same length. Blot chips dry with a paper towel. ( rll and dab each end)
5) weigh each potatoes chip - record initial mass
6) transfer potato to boiling tube and time 20 mins, blot chips dry then re weigh+ record the final mass
7) calculate change in mass and then calculate percentage change in mass

276
Q

What is the plant called when water Enters by osmosis

A

The vacuoles swells - its a turgid cell

277
Q

What is the plant called when water leaves by osmosis

A

Vacuole shrinks
Flaccid cell

278
Q

Describe a hypertonic solution

A

Contains more solutes and therefore has a lower water potential than a cell suspended in the solution

279
Q

Describe an isotonic solution

A

Contains the same amount of solutes and therefore has the same water potential as a cell suspended in the solution

280
Q

Describe a hypotonic solution

A

Contains less solutes and therefore has a higher water potential than a cell suspended in the solution

281
Q

Explain plasmolysis

A

Water has moved out the cell by osmosis down a water potential gradient through a partially permeable membrane

Hypertonic solution as water moves out of cells as there is a lower water potential out of the cell.

This causes the Tonoplast to pull away from the membrane through plasmolysis

282
Q

Describe absorption in the Small intestines

A

Villi + micro villi - inc rate of absorption by inc. SA
Thin epithelial calls as walls - short diffusion pathway
Thick capillary network - maintains conc, gradient (blood capillaries absorb glucose and amino acids)

283
Q

What is the lacteal

A

Tiny lymphatic vessel

284
Q

What does rhe lacteal absorb

A

Fatty acids
Glycerol

285
Q

Properties of villi

A
  • well supplied with blood vessels - blood can carry away absorbed molecules maintains a concentration gradient
  • thin walls- short diffusion pathway

-villi can move helps maintain diffusion gradient

  • they inc overall SA
  • villi contain muscle with contract regularly mixing products of digestion. So always glucose rich food next to the epithelial cells of the villi
286
Q

What projects from the villi

A

Microvilli

287
Q

What is the role of active transport in absorption

A

Some glucose is taken up by active transport , so all glucose can be taken up by blood

288
Q

Why is active transport needed in the SI for absorption

A

Diffusion can only make both sides of epithelium equal
So not all available glucose is absorbed - so some glucose would pass the body

289
Q

What is rhe sodium potassium pump

A

(indirect active transport)
Sodium leaves rhe cell while potassium enter the cell ( for every 2 potassium is 3 sodium)
This is controlled by ATP

290
Q

Describe cotransport in epithelial cells

A

Symport
Sodium ions enter the cell down there diffusion gradient
With a glucose / amino acid (not down a conc, gradient)

291
Q

Describe the transport of glucose / amino acids out of epithets cell into blood

A

Facilitated diffusion
Diffuse down a conc gradient

292
Q

What is solute potential

A

Measure of the reduction in water potential due to the presents of solute molecules

293
Q

What is pressure potential

A

Hydrostatic pressure to which water is subjected.
Usually but not always positive
(Sometimes called turgor)

294
Q

Explain Plasmolysis in a plant cell.

A

Hypertonic solution,
Water leaves the cell, and as sell wall is rigid rhe cell memebrane shrinks away from the cell wall.
This process is termed

295
Q

Explain turgor in a plant cell

A

Hypotonic
Water enters cell - cytoplasm takes on water, putting pressure on the cell membrane .
Swell
A pressure potential is generated when sufficient water has been taken up to cause the cell components to press against the cell wall

296
Q

Facilitated diffusion occurs when a substance is aided across a memebrane by a molecule called…

A

Ionophore

297
Q

What is rhe driving force for water up a plant
+ what contributes

A

The gradient in water potential

+ transpiration pull, cohesion and root pressure

298
Q

Benefits of transpiration

A

Cools the plant
+ maintain adequate mineral uptake

299
Q

Describes transportation pull

A

Water lost from the air spaces by evaporation through stomata is replaced by water from the mesophyll cells

The constant loss of water to the air creates a lower water potential in the leaf cells that in the cells further away from the evaporation sight , water is pulled through a plant along a dec. gradient in water potential

300
Q

Describe cohesion

A

The transpiration is assisted by the special cohesive properties of water. Water molecules cling to each other as they are pulled through the plant and they adhere to the walls of the xylem.
This creates one unbroken collet of water though the plant , the upward pull on the cohesive sap creates tension . This facilitated water uptake and movement through a plant

301
Q

Describe root pressure

A

Water entering the soil creates root pressure
Weak push effectfor the water upward movement through a plant

302
Q

Describe the cholera bacteria

A

Prokaryote
Corkscrew flagellum damages channel proteins so water leaves cell

303
Q

What does cholera cause

A

Dehydration and diarrhoea

304
Q

What is diarrhoea

A

A disorder of the intestines where watery feared are produced frequently

305
Q

Causes of diarrhoea

A

Damage to epithelial cells lining the intestines
Loss of micro villi due to toxins
Excessive secretion of water due to toxins in the intestines eg, cholera toxin

306
Q

Treatment for diahorrea

A
  • vital to rehydrate - water alone is not enough as water is not being absorbed by the intestines. Water in cases is being lost be cells
  • some ions ( electrolytes) are also required to replace those lost by epithelial cells
  • oral rehydration therapy
307
Q

How does oral rehydration therapy work

A

Using one carrier proteins in cell surface membrane
there are more than one carrier in the CSM that absorb sodium ions. So they use these alternative pathways
As sodium ions are absorbed, the water potential inc the cell falls and water enters the cell by osmosis

308
Q

How do you rehydrate yourself

A

Water to rehydrate the tissue
Sodium ions to replace those lost from epithelial cells
( making optimum use of the sodium glucose carrier proteins)
Glucose - to provide energy and stimulate the uptake of sodium ions from the intestines
Potassium - to stimulate appetite and replace lost K+ ions
Other electrolytes - chloride and citrate ions to help balance electrolytes in all cells

309
Q

How to use oral rehydration therapy

A

Boiled water mixed. With packets of electrolyte powdered
Does t require a trained person

310
Q

What are antigens

A

Molecules that can trigger an immune response when detected by the body

311
Q

What biological molecules are antigens usually made of

A

Proteins

312
Q

Where are antigens usually found

A

On the surface of cells

313
Q

What are antigens used by the immune system to identify

A

Pathogens
Abnormal body cells ( eg, cancer or pathogen infected cells, which have abnormal antigens on their surface
Toxins
Cells from other individuals of the same species (eg, organ transplant)

314
Q

Is a macrophage a phagocytes

A

Yes

315
Q

What is a phagocytes

A

A type of white blood cell that carries out phagocytosis

316
Q

Where are phagocytes found

A

In the blood amd in tissues

317
Q

What are the first cells to respond to an immune system trigger inside the body

A

Phagocyte

318
Q

Explainphagocytosis

A

1) a phagocyte recognises the foreign antigens on a pathogen
2) the cytoplasm of the phagocyte moves round the pathogen , engulfing it
3)The pathogen is now contained in a phagocytic vacuole (a bubble) in the cytoplasm of the phagocyte.
4) A lysosome (an organelle that contain enzymes called lysozymes) fuses with the phagocytic vacuole. The lysozymes break down the pathogen.
5) The phagocyte then presents the pathogen’s antigens — it sticks the antigens on its surface to activate other immune system cells.

319
Q

What is another name for a T-cell

A

T-lymphocytes

320
Q

Describe a T-cell

A

It has receptor proteins on its surface that bind to complementary antigens presented to it by the phagocytes
This activates the T-cell
Differnt types of Tcells respond in differnt ways. For example, helper T-cells (TH cells) release chemical signals that activate and stimulate phagocytes and cytotoxic T-cells (Tc cells) which kills abnormal and foreign cells.
TH cells also activates B-cells, which secrete antibodies

321
Q

Do T-cells activate B-cells

A

Yes

322
Q

Describe a B cell

A

a type of white blood cell
There covered with antibodies
Each B-cell has a differnt shaped antibody on its membrane , so differnt one bind to differnt shaped antigens

323
Q

What is an antibody

A

Proteins that bind antigens to form an antigen-antibody complex

324
Q

Describe what happens when the antibody on the surface of the B cell meets a complementary shaped antigen

A

It binds to it
This together with substances released form helper T-cells, activates the a cell. Thus process is called cola l selection
Thus activated B-cell divides into plasma cells

325
Q

Are plasma cells identical to the B cells

A

Yes they’re clones

326
Q

What do plasma cells do

A

They secrete lots of antibodies specific to the antigen. These are called monoclonal antibodies
They bind to the antigen on the surface of the pathogen to form lots of antigen-antibody complexes

327
Q

How many binding sites does an antibody have

A

2

328
Q

How many pathogens can an antibody bind to at the same time
And what does this that pathogens will do

A

2
Become clumped together - called agglutination

329
Q

What happens when pathogens are clumped together by antibodies

A

Phagocytes then bind to the antibodies and phagocytes many pathogens at once.
Thus process leads to the destruction of pathogens carrying this antigen in the body

330
Q

What biological molecules are antibodies made up of

A

Proteins

331
Q

What does the specificity of an antibody depend on

A

It’s variable region, which form rhe antigen binding site

332
Q

How do the variable regions differ in each antibody

A

A unique tertiary structure ( due to the different amino acid sequences) that’s complementary to one specific antigen.

333
Q

Do all antibodies have the same constant regions

A

Yes

334
Q

What 2 things is the immune response split into

A

The cellular response and humoral response

335
Q

What is the cellular immune response

A

The Tcells and other immune system cells that they interact with,
Eg, phagocytes, form cellular response

336
Q

What is the humoral response

A

B-cells, clonal selection and the production of monoclonal antibodies form the humoral response

337
Q

Are both cellular and humoral needed to remove a pathogen form the body

A

Yes

338
Q

Explain why in healthy individuals out lymphocytes do not destroy our own body cells

A

In the fetus, lymphocytes collide exclusively with body own cells as infection is rare in the fetus because it’s protected by the mother/placenta some sites will have receptors that fit those body own cells. These either die or are suppressed remaining lymphocytes only fits foreign material.

An adult lymphocytes produced in bone marrow, initially only encounter self antigens, any lymphocytes that show an immune response to these self antigens, undergo programs cell death (apoptosis) Before they can differentiate into mature lymphocytes
No clones of these anti-self lymphocytes will appear in the blood. Only those that might respond to non-antigens.

339
Q

define immunity

A

Immunity is the ability of organisms to resist infection by protecting against disease - causing microorganisms or their toxins that invade their bodies- it involves the recognition of foreign material (antigens)

340
Q

What is involved in specific immune response

A

Lymphocytes

341
Q

What do lymphocytes provide

A

Long term immunity

342
Q

What are the 2 differnt types of lymphocytes

A

B
T

343
Q

What is an antigen

A

Antigen is any part of an organism or substance that is recognised as non-self (foreign) by the immune system and stimulates an immune response

344
Q

What type of biological molecule are proteins (usually ) made of

A

Antigens are usually proteins that are part of the cell surface memebrane of cell wall of an invading cell. The presence of antigens trigger production of antibodies

345
Q

similarity of B and T cells

A
  • b and t are both lymphocytes
  • both are produced by stem cells in bone marrow
  • responsible for specific immune response which provides long term community
346
Q

Differences between b and T cells

A
  • b cells mature in the bone marrow however T cells pasture in thymus gland
  • b cells are associated it’s humoral immunity ( that is imunity involving antibodies that are present in body fluids or ‘humour’ such as blood plasma’
    However Tcells are associated with cells mediated immunity ( thus us imunity involving body cells)
347
Q

What is an antibody and which of the B or T cells are response for producing them

A

B cells
Antibody’s are proteins which specific binding sites synthesised by B cells ( when body is infected by non self material , a b cell produces a specific antibody )

348
Q

Structure if an antibody

A

Each antibody has two identical binding slides. They are complimentary to a speciifc antigen.
Antibodies are made up of four polypeptide chains, the chains of one pair along and heavy andare called heavy chains, while the chains of the other pair are shorter, and known as light chains

Each antibody has a specific binding site that fits very precisely onto a specific antigen to form an antigen antibody complex

The binding site is different on different antibodies and is therefore called the variable region

Each binding site consists of a sequence of amino acids that form a specific 3-D shape that binds directly to a specific antigen

The rest of the antibody is a constant region to the receptors on cell, such as b cells

349
Q

3 cell organelles that might be in large quantities In plasma cells as they can produce 2000 antibodies a second and why

A

Ribosomes - site of protein synthesis
Mitrcohcodira- atp which can be sued in protein synthesis
RER- fold the protein made in the ribosomes so antibodies take up the correct 3D tertiary structure

350
Q

What does phago and cyte mean in phagocyte

A

Phago- to eat
Cyte - hallow as cell or container

351
Q

What are pseudopods

A

extension of rhe cytoplasm

352
Q

What are antigens presenting cells

A

Ability to take up extra cellular particles

353
Q

How does histamine help phagocytes leave the blood

A

Causes blood vessels to become permeable so they can leave the blood

354
Q

Describe phagocytosis

A

The process by which white blood cells engulf and subsequently digest pathogenic microorganisms.

355
Q

When pathogens infect the body they realise what

A

Chemical products called chemiattractrants

356
Q

What does chemoattractants cause and what is this process called

A

Phagocytes to migrate toward the pathogen along a concentration Gradient
Called chemotaxis

357
Q

How does phagocyte bind to the surface of the pathogen

A

Cell surface membrane of the phagocytes has several protein receptors that are able to bind to the complementary antigens present om the surface of the pathogen

358
Q

What happens when the phagocytes bind to the surface of the pathogen

A

The phagocytes call membrane extent outwards around the site of attachment and surrounds the material, effectively engulfing it. The pathogen is now enclosed in a mebrane bound sac (vesicle) called phago some

359
Q

What is rhe membrane bound sac (vesicle) that a pathogen gets enclosed in in phagocytosis called

A

Phagosome

360
Q

When the pathogen is enclosed in the phagosome, what happens next in phagocytosis

A

The phagosome moves towards rhe cell interior and fuses with a lysosome. Thus fusion releases lysosomal enzymes onto the injected pathogen
The enzyme digest the pathogen by the process of hydrolysis

361
Q

How can bacteria by destroyed

A

By hydrolysis of their cell walls

362
Q

What happens to the soluble products of digestion

A

Absorbed into the cytoplasm of the phagocyte

363
Q

When an antigen enters the body from the frost time it activates the immune system . What is this response called

A

Primary response

364
Q

Is the primary response is slow or fast + why

A

Slow becuase there arnt many B-cells that can make the antibodies needed to bind to it

365
Q

Explain the primary response

A

B-cells make antibodies needed to bind to it, eventually the body will produce enough of the right antibodies to overcome the infection. Meanwhile the infected person will show symptoms of the disease.
After being exposed to an antigen, both t and b cells produce memory cells. These memory cells remain in the body for a long time. The person is now immune ( and has the ability to respond quickly ro a second infection

366
Q

What do memory T cells do

A

Remember specific antigens and will recognise a second time in a row

367
Q

What do memory B cells do

A

Record specific antibodies need to bind the antigen

368
Q

Describe the secondary response

A

Is the same pathogen enters the body again the immune system will produce a quicker stronger immune response

Colonal selection happens faster. Memory B-cells are activated and divide into plasma cells that produce the right antibodies to the antigen. Memory Tcells are activated and divide into the correct type of Tcells to kill the cell carrying the antigen

369
Q

T or f
The secondary response oftern gets rid of the pathogen before you begun to show any symptoms

A

T

370
Q

How do antibodies lead to the destruction of antigens

A

Antibodies cause agglutination if bacteria cells, this means that the binding other the specific antibody to the complementary antigen on the bacterial cells cause clumps if bacteria cells to form - thus clumping toughest make its easier for the phagocytes to locate the bacteria as they are less spread out within the body
The antibody’s act as markers to stimulate the phagocytes to engulf the bacteria cells to which they are attracted

371
Q

What is clonal selection

A

Process of specific b cells undergoing mitosis

372
Q

Antigen molecules fit the receptors of one b cell only (humoral response) what happens then

A

Then takes antigen from pathogen and puts it on its surface (antigen presenting cell) helper T cells bind to antigen B cells
Stimulates mitosis

373
Q

Describe the humoral response

A

There are millions of differnt B lymphocytes in the body
Each has a specific shape of receptor (actually a membrane-bound antibody) on its cell surface membrane.
When a foreign antigen enters the blood or tissue fluid, there will be one B ceil with a receptor/antibody that is complementary to that of the antigen.

The antibody on that specific, B-cell, therefore bind to the antigen to form an antigen antibody complex. This binding cause the antigen to enter the specific cell by the process of endocytosis.

The antigen is then presented on the cell surface membrane of the cell. We say it has been processed.

help T cells then bind to the processed antigens. This activates specific B cell, causing it to divide rapidly by the process of mitosis, the result is the large clone of the cells that are genetically identical

the clone of cells, then differentiate into one of two cell types, the majority becomes plasma cells. These secrete soluble antibodies that are the correct shape to bind to the foreign antigen. Although they only live for a few days each can make approximately 2000 antibodies a second they responsible for the immediate defence of the body against infection should they count to the same foreign material at a later date they can divide very rapidly into plasma cells and yet more memory cells and increased amount of antibodies secreted at a faster rate

other cells differentiate into memory cells. These remain in the body circulating in the blood and tissue fluid for a long time. This secondary immune response shows that the antigen is destroyed before symptoms of disease develop.

374
Q

What do lymphocytes respond to

A

Own cells that have been infected by non self material ( from a differnt species )
And
Other individuals from the same species becuase genetically differnt ( and so have differnt antigens on their CSM)

375
Q

How can a T-lymphocyte distinguish invader cells from normal cells

A

Phagocytes that have engulfed and hydrolysed a pathogen prevent some pathogens antigens on their own CSM

Body cells invade by a virus present some of the viral antigens on they own CSM

Transplanted cells from individuals of the same species have differnt antigens on their CSM

Cancer cells are differnt from normal body cells and present antigens on thru CSM

376
Q

Cells that display foreign antigens on their surface are called what?

A

Antigen presenting cells as they can present antigens of other cells on their own CSM

377
Q

What do T lymphocytes only respond to

A

Antigens that are presented on a body cell
(Rather than antigens in the body fluid)

378
Q

What response is T lymphocytes involved in

A

Cell mediated immunity

379
Q

How many differnt antigens does each T cell respond to

A

A single antigen

380
Q

What are the stages in response of T lymphocytes to infection by pathogen

A

1) pathogens invade body cells or are taken in by phagocytes
2) the phagocyte phase places antigens form the pathogen on its CSM
3) receptors on a specific helper T-cell fit exactly onto there antigens
4) thus attachment activated the T cells to divide By mitosis and form a clone of genetically identical cells

381
Q

What 4 things do cloned T cells do

A
  • develop into memory cells that enable a rapid response to future infection by the same pathogen
  • stimulate phagocytes to engulf pathogens by phagocytosis
  • stimulated B cells to divide and secrete their antibody s
  • activate cytotoxic T cells
382
Q

How do cytotoxic T cells kill infected cells

A

Produces a protein called perforin that makes holes in the CSM. These holes mean cell memebrane becomes freely permeable to all substances and the cell dies.

383
Q

What do cytotoxic T cells do

A

Kill abnormal cells and body cells that are infected by pathogens

384
Q

What are T cells more efficient against

A

Viruses

385
Q

Why are T cells most efficient against viruses

A

As viruses replicate in cells (as viruses use living cells)

386
Q

Why can’t HIV replicate itself
So what does it do

A

It’s a virus
So it uses it genetic material to instruct the host cells biochemical mechanisms to produce the components required to make HIV

387
Q

How does HIV infect cells and replicate

A

• Following infection HIV enters the bloodstream
• A protein on the HIV readily binds to a protein called CD4. While this protein occurs on a number of different cells, HIV most frequently
attaches to helper T cells
• The protein capsid fuses with the cell-surface membrane. The RNA and enzymes of HIV enter the helper T cells
• The HIV reverse transcriptase converts the virus’s RNA into DNA.

The newly made DNA is moved into the helper T cells nucleus where it is inserted into the cell’s DNA.
• The HIV DNA in the nucleus creates messenger RNA using the cells enzymes. Thus mRNA contains the instruction for making new viral proteins and the RNA to go into the new HIV

• The mRNA passes out of the nucleus through a nuclear pore and uses the cells protein synthesis mechanisms to make HIV particles.
• The HIV partides break away from the helperT cell with a piece of its cell surface membrane surrounding them which forms their lipid envelope.

388
Q

Once infected wuth HIV what is a person said to be?

A

HIV positive

389
Q

Replication of HIV oftern goes into dormancy and only recomencds when

A

When leading to aids many years later

390
Q

How does HIV cause the symptoms of aids

A

The human immunodeficiency virus specifically attacks helper T cells. HIV causes AIDS by killing or interfering with the normal functioning of helper T cells. An uninfected person normally has berneen 800 and 1200 helper T cells in each mm3 of blood. In a person suflering from AIDS this number can be as low as 200 mm. helper T cells are important in cell mediated immunity. Without a sufficient number of helper T cells, the immune system cannot stimulate B cells to produce antibodies or the cytotoxic T cells that kill cells infected by pathogens. Memory cells may also become infected and destroyed. As a result, the body Is unable to produce an adequate immune response and becomes susceptible to other infections and cancers. Many AIDS sufferers develop infections of the lungs, intestines, brain and eyes, as well as experiencing weight loss and diarrhoea. It is these secondary, diseases that ultimately cause death.

391
Q

How many helpers T cells does an uninflected person have

A

800 - 12000 in each mm3 of blood

392
Q

How many helpers T cells does a person suffering with aids have

A

As low as 200mm-3

393
Q

What does HIV stand for

A

Human immunodeficiency virus

394
Q

What does ELISA stand for in the elisa test

A

Enzyme linked immunosorbant assay

395
Q

Why does The elisa test do

A

Detects the presence of a protein in a Sample and the quantity

396
Q

Describe the steps of the ELISA test

A

1) apply the sample to a surface, for example a slide, it which all the antigens in the sample will attach

2) wash the surface several times to remove any unattached antigens

3) add the antibody that is specific to the antigen we are trying to detect and leave the two to bind together

4) wash rhe surface to remover excess antibody’s

5) add a second antibody that binds with the first antibody . Thus secondary antibody has an enzyme attached to it

6) add the colourless substrate of the enzyme. The enzyme acts on the substrate to change ut to o a coloured product

7) the amount of the antigen present is relative to the intensity of the colour

397
Q

What can the ELISA test be used to detect

A

HIV and the pathogens of disease including tuberculosis and hepatitis
( ELISA is useful as it measures quantity which is imporstant in drug and allergen tests)

398
Q

What is passive immunity

A

Passive immunity is produced by the introduction of antibodies into individuals from an outside source. No direct contact with the pathogen or its antigen is necessary to induce immunity.

399
Q

How quickly is immunity aquired with passive immunity

A

Immediately

400
Q

Does passive immunity form lasting immunity and why

A

No as the antibodies are not be produced by the individuals themselves, the antibodies are not replaced when there broken down, no memory cells are formed

401
Q

Examples of passive immunity

A

Examples of passive immunity include anti-venom given to the victims of snake bites and the immunity acquired by the fetus when antibodies pass across the placenta from the mother.

402
Q

What is active immunity

A

produced by stimulating the production of antibodies by the individuals’ own immune system. Direct contact with the pathogen or its antigen is necessary.

403
Q

How long does it take immunity to develop for active immunity

A

takes time

404
Q

Is active immunity long lasting

A

Yes

405
Q

What are the two types of active immunity

A

Natural
Artificial

406
Q

What is natural active immunity

A

results from an individual becoming infected with a disease under normal circumstances. The body produces its own antibodies and may continue to do so for many years.

407
Q

What is artificial active immunity

A

forms the basis of vaccination (immunisation). It involves inducing an immune response in an individual, without them suffering the symptoms of the disease.

408
Q

What is a vaccination

A

appropriate disease antigens into the body, either by injection or by mouth. The intention is to stimulate an immune response against a particular disease.

409
Q

Whats in a vaccine

A

contains one or more types of antigen from the pathogen. These antigens stimulate the immune response

410
Q

Why is the result form a pathogen slight

A

only a small amount of antigen has been introduced,

411
Q

After a vaccine what is key got long lasting g immunity

A

Memory cells

These remain in the blood and allow a greater, and more immediate, response to a future infection with the pathogen.

412
Q

What is the result of a vaccination

A

The result is that there is a rapid production of antibodies and the new infection is rapidly overcome before it can cause any harm and with few, if any, symptoms.

413
Q

Features of a successful vaccination programme

A

economically available in sufficient quantities to immunise most of the vulnerable population.

few side-effects, if any, from vaccination. Unpleasant side-effects may discourage individuals in the population from being vaccinated.
• Means of producing, storing and transporting the vaccine must be available. This usually involves technologically advanced equipment, hygienic conditions and refrigerated transport.
• There must be the means of administering the vaccine properly at the appropriate time. This involves training staff with appropriate skills at different centres throughout the population.
• It must be possible to vaccinate the vast majority of the vulnerable population to produce herd immunity.

414
Q

What is herd immunity

A

Herd immunity arises when a sufficiently large proportion of the population has been vaccinated to make it difficult for a pathogen to spread within that population.

Where the vast majority of the population is immune, it is highly improbable that a susceptible individual will come in contact with an infected person.

415
Q

Why is herd immunity important

A

Herd immunity is important because it is never possible to vaccinate everyone in a large population.

416
Q

Why is it never possible to vaccinate everyone in a population

A

For example, babies and very young children are not vaccinated because their immune system is not yet fully functional. It could also be dangerous to vaccinate those who are ill or have compromised immune systems.

417
Q

What is needed to achieve herd immunity

A

To achieve herd immunity, vaccination is best carried out at one time. This means that, for a certain period, there are very few individuals in the population with the disease and the transmission of the pathogen is interrupted.

418
Q

Why may vaccination not eliminate disease

A

Vaccination fails to induce immunity in certain individuals, for example people with defective immune systems.

• Individuals may develop the disease immediately after vaccination but before their immunity levels are high enough to prevent it.
These individuals may harbour the pathogen and reinfect others.

• The pathogen may mutate frequently, so that its antigens change suddenly rather than gradually. This means that vaccines suddenly become ineffective because the new antigens on the pathogen are no longer recognised by the immune system. As a result the immune system does not produce the antibodies to destroy the pathogen. This antigenic variability happens with the influenza virus, which changes its antigens frequently. Immunity is therefore short-lived and individuals may develop repeated bouts of influenza during their lifetime.

There Amy be so many varieties of z particular pathogen that it Is almost impossible to develop a vaccine that is effective against all.

Cerain pathogens ‘hide’ from the bodys immune system. either by concealing themselves inside cells or by living in places out of reach such as in the intesines, for example, the cholera
• Individuals may have objection to vaccination for religious, ethical or medical reasons

419
Q

What are some ethical questions of using a vaccines

A

• The production of exsisiting vaccines, and the development of new ones, often involves the use of animals. How acceptable is this?
• Vaccines have side-effects that may sometimes cause long-term harm. How can the risk of side-effects be balanced against the risk of developing a disease that causes even greater harm?
• On whom should vaccines be tested? How should such trials be carried out? To what extent should individuals be asked to accept risk in the interests of the public health?
• Is it acceptable to trial a new vaccine with unknown health risks only in a country where the targeted disease is common, on the basis that the population there has most to gain if it proves successful?
• To be fully effective the majority, and preferably all, of the population should be vaccinated. Is it right, in the interests of everyone’s health, that vaccination should be compulsory? If so, should this be at any time, or just when there is a potential epidemic? Can people opt out? If so, on what grounds: religious belief, medical circumstances, personal belief?
• Should expensive vaccination programmes continue when a disease is almost eradicated,

420
Q

Vaccines contain antigens that cause you body to produce what

A

Memory cells

421
Q

how do the vaccines exist in a vaccine

A

Either free or attached to a dead or weakened (attenuated) pathogen

422
Q

What is the disadvantage of a vaccine been taken orally

A

that it could be broken down by enzymes in gut or the molecules of the vaccine may be too large to be absorbed into the blood

423
Q

Why are booster vaccines given later on

A

To make sure that memory cells are produced

424
Q

What do antigens on the surface of a pathogen activate

A

Primary response

425
Q

What is the secondary response

A

When you’re infected a second time with the same pathogen (which has the same antigens on its surace they activate the secondary response and you don’t get ill.

426
Q

What is antigenic variation

A

When pathogens can change their surface antigens

427
Q

If antigenic variation has occurred
What would happen if you are infected for a second time
Would you get ill?

A

The memory cells produced for the first infection, will not recognise the different antigens.
So the immune system has to carry out the primary response again
Yes , as the primary response takes time to get rid of the infection

428
Q

how antigenic variation affects the production of vaccines to help prevent people catching influenza

A

The influenza (flu) vaccine changes every year. That’s because the antigens on the surface of the influenza virus change regularly, forming new strains of the virus.
2) Memory cells produced from vaccination with one strain of the flu will not recognise other strains with different antigens. The strains are immunologically distinct.
3) Every year there are different strains of the influenza virus circulating in the population, so a different vaccine has to be made
4) New vaccines are developed and one is chosen every year that is the most effective against the recently circulating influenza viruses.
5)governments and health authorities the implement a program of vaccination using the most suitable vaccine

429
Q

What is natural passive immunity
Example

A

this is when a baby becomes immune due to the antibodies it receives from its mother, through the placenta and in breast milk.

430
Q

Artificial passive immunity

A

this is when you become immune after being injected with antibodies from someone else.

431
Q

What are monoclonal antibodies

A

Antibodies produced form a single group of genetically identical B-cells ( plasma cells). This means they are identical in structure.

432
Q

Why are antibodies very specific

A

Their binding sites have a unique tertiary structure.

433
Q

How can you use monoclonal antibodies to target drugs at cancer cells

A

Different cells in the body have different surface antigens.

2) Cancer cells have antigens called tumour markers that are not found on normal body cells.

3)
Monoclonal antibodies can be made that will bind to the tumour markers.

4) You can also attach anti-cancer drugs to the antibodies.

5) When the antibodies come into contact with the cancer cells they will bind to the tumour markers.

6) This means the drug will only accumulate in the body where there are cancer cells.

7) So, the side effects of an antibody-based drug are lower than other drugs because they accumulate near specific cells.

434
Q

What hormone do pregnancy tests detect

A

HCG
Human chorionic gonadotropin

435
Q

Where is human chorionic gonadotropin found

A

In the urine of pregnant women

436
Q

How do pregnancy tests work

A

1) The application area contains antibodies for hCG bound to a coloured bead (blue).
2) When urine is applied to the application area any hCG will bind to the antibody on the beads, forming an antigen-antibody complex.
3) The urine moves up the stick to the test strip, carrying any hCG beads with it.
4) The test strip contains antibodies to hCG that are stuck in place (immobilised).
5) If there is hCG present the test strip turns blue because the immobilised antibody binds to any CG — concentrating the hCG-antibody complex with the blue beads attached.if no HCG present the beads will pass through the test area without binding to anything and so it won’t go blue

437
Q

What can ELISA be used to test for

A

Pathogenic infections
Allergies

438
Q

What is direct ELISA

A

Uses a single antibody that is complementary to the antigen you are testing fro

439
Q

What is indirect ELSA

A

Uses 2 antibodies

440
Q

What does HIV lead to

A

AIDS

441
Q

What does AIDS stand for

A

Acquired immune deficiency syndrome

442
Q

What is in the core of the HIV virus

A

Genetic material (RNA) and some proteins ( including the enzymes reverse transcriptase, which is needed for virus replication )

443
Q

What is the outer coating of protein in HIV called

A

Capsid

444
Q

What is the extra outer layer of HIV called
And what is it made from

A

Envelope
Membrane stolen form the cell membranes of a previous host cell

445
Q

What is sticking out of the envelope in a HIV virus

A

copies of an attachment proteins that help HIV attach to the host helper T-cell

446
Q

What does HIV replication inside

A

Helper T-cells of the host

447
Q

What is the latency period of HIV

A

The infected person won’t experience any symptoms
As the HIV replication drops to a lower level

448
Q

What are the inital symptoms of aids

A

Minor infections of mucous membranes, and recurring respiratory infections

449
Q

What happens as AIDS progresses

A

The number of immune system cells decrease further
Patients become susceptible to more serious infection including chronic diarrhoea, severe bacterial infections and tuberculosis

450
Q

What happens in the late stages of AIDS

A

patients have a very low number of immune system cells and can develop a range of serious infects such as toxoplasmolysis of the brain and candidiasis of the respiratory system
Its these serios infection that kill aids patients not HIV itself

451
Q

What does survival time with AIDS depend on

A

Existing infection
Strain of HIV they are infected with
Age

452
Q

What do antibiotics kill

A

Bacteria

453
Q

How do antibiotic kill bacteria

A

By interfering with their metabolic reactions

They target the bacterial enzyme and ribosomes used in these reactions

454
Q

Why do antibiotics not work against viruses

A

Antibiotics kill bacteria by interfering with their metabolic reactions.
They target the bacterial enzymes and ribosomes used in these reactions.
2) Bacterial enzymes and ribosomes are different from human enzymes and ribosomes. Antibiotics are designed to only target the bacterial ones so they don’t damage human cells.
3) Viruses don’t have their own enzymes and ribosomes — they use the ones in the host’s cells. So because human viruses use human enzymes and ribosomes to replicate, antibiotics can’t inhibit them because they don’t target human processes.

455
Q

What are most antiviral drugs designed to target

A

The Few virus specific enzymes that exist

456
Q

How do antiviral drugs target HIV

A

HIV uses reverse transcriptase to replicate. Human cells don’t use this enzyme so drugs can be designed to inhibit it without affecting the host cell. These drugs are called reverse-transcriptase inhibitors.

457
Q

Is there a cure or vaccine for HIV

A

No

458
Q

How can HIV progression be slowed down

A

Antiviral drugs

459
Q

What is the best way to control HIV infection in a population

A

Reducing the spread

HIV can be spread via unprotected sexual intercourse, through infected bodily fluids (e.g. like blood from sharing contaminated needles) and from a HIV-positive mother to her fetus. Not all babies from HIV-positive mothers are born infected with HIV and taking antiviral drugs during pregnancy can reduce the chance of the baby being HIV-positive.

460
Q

What are epitopes

A

Differnt parts of the antigen that can be recognised as foreign by the immnne system and can stimulate an immune response

461
Q

Pathogen deification

A

A microorganism that can potentially cause disease

462
Q

Humoral response definition

A

Term given to describe the way in which B lymphocytes produce antibodies in response to infection

463
Q

Cellular response definition

A

Tea lymphocytes respond to an antigen presenting cell

464
Q

What chemicals are released to help phagocytes squeeze through gaps in capillary walls?

A

Histamines

465
Q

What are polyclonal antibodies

A

Mixture of differnt antibodies

466
Q

What are monoclonal antibodies

A

Antibodies of a single type that are isolated and cloned

467
Q

Why would you use monoclonal antibodies not polyclonal

A

One antigen may interfere with another
Expensive process so cheaper to only Produce one antibody

468
Q

Uses of monoclonal antibodies

A

To separate a chemical from a mixture
Immunoassay - to estimate the quantity of a substance in a mixture (pregnancy test)
Cancer treatment
Transplant surgery

469
Q

How are monoclonal antibodies used in cancer treatments

A

To deliver cytotoxic drugs to cancer cells, cancer cells have antigens on surface that are not found on healthier cells

470
Q

How are monoclonal antibodies used in transplant surgery’s

A

Can be used to block t-cells that will cause rejection of a transplanted organ

471
Q

What do B cells of mouse make

A

Polyclonal antibodies

472
Q

Where are b cells extracted from in mouse for ,monoclonal antibody production

A

Spleen

473
Q

What do monoclonal antibodies have to be before that are used to treat human disease and why

A

Humanised
So human immune system will accept the antibodies and not recognise them as foreign

474
Q

Describe the monoclonal antibody production

A

1) inject foreign material into mouse
2) B-cells of mouse make polyclonal antibodies
3) extract b cells from the spleen
4) mix b cells with cells from cancer tumour in vitro
5) the detergent, breaks the cell surface membrane, allowing both cells to fuse
6) if few cells are separated, using a microscope and cultured to form a clone of cells
7) Each cell is tested any producing the required antibody, grown on a large scale
8 humanised

475
Q

Why are the b cells mixed with tumour cells in monoclonal antibody production?

A

Tumour cells divide rapidly, which makes the process more efficient

476
Q

What is the name of the resulting cell from the fusion of myeloma and B cells from a mouse in monoclonal antibody production?

A

Hybridoma

477
Q

What are some ethical issues of monoclonal antibodies

A

Deliberately inducing cancer to mice
Transgenic mice are used to eliminate the humanisation procedure. Is genetic engineering ethical
Death association with the use of monooinal antibodies in the treatment of multiple sclerosis
Saftey if feasting new medicine ( drug trials)

478
Q

Passive or active immunity
Long lasting protection

A

Active

479
Q

Passive or actuev immunity
Short lasting

A

Passive

480
Q

Passive or active immunity
Exposure to antigen

A

Active

481
Q

Passive or active immunity
Immediate protection

A

Immediate

482
Q

Passive or active immunity
Memory. Cells produced

A

Active

483
Q

Passive or active immunity
Antibodies are broken down after initial response

A

Both

484
Q

Describe the process of vacccinatuon

A

The vaccine is administered
It contains a weakens, dead, dilute or heat attenuated version of the disease
The immnuse system identifies these foreign sustances
Once antigens are identified, b cells produce proteins that circulate in the blood, these proteins are called antibodies
Memory cells produced in response to the antigen are available to fight of the disease if exposed later on

485
Q

What did the 1998 study in the MMR vaccine believe there where links between

A

The MMR vaccine and autism

486
Q

Why was the 1998 study on the link between autism and MMR vaccine unreliable

A

Very small sample size of 12 children- which increased the likelihood of the results being due to chance
The study may have been biased because one of the scientists was trying to gain evidence for a lawsuit against the MMR vaccine manufacturer
Studies carries out by differnt scientists found no links between autism and the MMR vaccine

487
Q

What further scientific studies where done to sort out the confilicting evidence of the proposed link between MMR vaccine and autism

A

2005 Japanese study
Looked into medical records of 30,000 children born between 1988 and 1996, and counted number of children that developed autism before the age of seven
The mmr jab was first introduced in Japan in 1989 and was stopped in 1993. During this time the Mmr vaccine was administered to children at 12 month

488
Q

What should you do when asked to Descirbe a graph

A

Use data
Describe the increases and decreases

489
Q

What conclusion would you draw between mmr vaccine and autism

A

There is no link

490
Q

Why was the 2005 study of MMR and autism better than the 1998 study

A

The sample size was larger so the results are less likely to be due to chance

A-level Biology (8 decks)

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