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Biology Paper 1/2 > Cells 2 > Flashcards

Cells 2 Flashcards

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1
Q

Samsung notes(CELL FLASHCARDS)

A

YASSSS

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2
Q

Define nucleus

A

Site of DNA replication and transcription
Contains the genetic code

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3
Q

Name all 5 structures in a nucleus

A

Nuclear envelope
Nuclear pores
Nucleoplasm
Chromatin
Nucleolus

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4
Q

What is nuclear envelope, Histone and the function of nucleolus

A

Nuclear envelope- outer and inner membrane
Chromatin- protein bound in linear DNA
Nucleolus- makes ribosomes

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5
Q

Define mitochondria

A

Site of aerobic respiration
Contains DNA that codes for enzymes in respiration

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6
Q

Name 5 parts of the mitochondrion

A

Inner membrane
Outer membrane
IMS(Inter membrane space)
Matrix
Cristae(folding of the inner membrane)

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7
Q

What is RER AND SER

A

RER: Protein synthesis
SER: Synthesises and processed lipids and carbohydrates

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8
Q

Define Cisternae

A

Fluid filled sacks surrounded by ribosomes

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9
Q

Define Ribosomes
What are the 2 sizes and where are they found

A

Site of protein synthesis
70s 80s
70s - Prokaryotes, Mitochondria, Chloroplast
80s- Eukaryotes

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10
Q

What are Ribosomes made from

A

Proteins and RNA

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11
Q

What is the function of Golgi apparatus/body and what does it make and what does that do

A

Processes and packages new lipids and proteins
Makes lysosomes
Breaks down worn out cells(autolysis)
Breaks down worn out organelles

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12
Q

What do lysosomes do

A

Lysosomes fuse with vesicles, releasing lysozomes(hydrolytic enzyme)
Break down worn out cells(autolysis)
Break down worn out organelles

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13
Q

Does an animal or plant cell have centriole

A

Animal cell

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14
Q

What is the structure and function of the cell membrane

A

STRUCTURE Made of a phospholipid bilayer
FUNCTION Controls movement of substances in and out of the cell

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15
Q

What is embedded in the phospholipid bilayer

A

Proteins (Channel/Carrier which are both Intrinsic proteins)
Antigens (Proteins on the otisde of a cell)

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16
Q

In a chloroplast, what is one stack of thylakoids called

A

Granum

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17
Q

What is the function of a chloroplast and where does this process take place

A

Site of photosynthesis
It takes place in Grana and Stroma

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18
Q

List 3 facts about the chloroplast

A

Double membrabe
Contains 70s Ribosomes
Contains circular DNA

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19
Q

What is the stroma in a chloroplast

A

Liquid that contains enzymes used for photosynthesis

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20
Q

What organelles have a double membrane
Which organelle has no membrane

A

Nucleus, mitochondria, chloroplast
Ribosome

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21
Q

What are 2 facts about the cell wall

A

Strong to prevent shape changes due to osmotic pressure
Rigid structure

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22
Q

What is the cell wall made from in plant cells Fungi and bacteria

A

PLANT - Cellulose
FUNGI - Chitin
BACTERIA - Murein/peptidoglycan

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23
Q

Give 2 facts about the cell vacuole
What is the membrane of a vacuole called

A

Maintains pressure
Keeps cell rigid
Tonoplast

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24
Q

What do golgi vesicles do

A

Vesicles fuse with plasma membrane releasing contents

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25
Q

A simple —- glass lens can act as a magnifying glass but such lenses work more effectively if they are used in —- in a compound light microscope

A

Convex
Pairs

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26
Q

In a light microscope, what is the distance between two objects that is needed for the two objects to be distinguishable
What property of light rays causes this
How can you overcome this issue
How does this work

A

0.2 um
Long wavelength
Using beams of electrons instead of beams of light
The shorter wavelengths means the beams of electrons in the electron microscope can distinguish between objects 0.1 nm apart

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27
Q

What is the formula for magnification

A

Magnification = Image size / Actual size

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28
Q

What is the resolution of a microscope

A

The minimum distance apart two objects can be in order for them to appear as seperate items

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29
Q

What does the resolving power of a microscope depend on

A

Wavelength or form of radiation used

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30
Q

What must you obtain before studying the structure and function of various organelles that make up cells

A

Large numbers of isolated organelles

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31
Q

Cell fractionation is the process where…

A

Cells are broken up and the different organelles they contain are separated out

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32
Q

Before cell fractionation, where must the tissue be placed and explain why

A

The tissue is placed in a cold, buffered solution of the same water potential as the tissue
COLD - To reduce enzyme activity that might break down organelles
SAME WATER POTENTIAL AS TISSUE - To prevent organelles from bursting or shrinki due to osmotic gain or loss of water
BUFFERED - The pH stays constant + doesn’t fluctuate. Any change in pH could denature enzymes

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33
Q

What are the two stages to cell fractionation

A

Homogenation
Ultracentrifugation

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34
Q

Explain homogenation

A

-Cells are broken up by a homogeniser (blender)
-This releases organelles from the cell
-The resultant fluid, homogenate is then filtered to remove any complete cells and large pieces of debris

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35
Q

What are the differences between prokaryotic cells and eukaryotic cells

A

-P is smaller and less complex
-P has no nucleus and no membrane bound organeles(ER, mitochondria, chloroplast)
-P contains 70s Ribosomes which are smaller
-in P, the cell wall is made from murein/peptidoglycan

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36
Q

Name the structures in a bacteria cell

A

Plasmid
Nucleoid
Plasma membrane
Mesosome
Cell wall
Capsule
Flagella

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37
Q

In a bacterial cell, there is plasmid, nucleoid, plasma membrane mesosome, cell wall capsule, flagella
Explain all of these

A

PLASMID small loop of DNA that contains genes(genes can be for antibiotic resistance)
NUCLEOID Circular DNA, free floating (no nucleur membrane), no histone
PLASMA MEMBRANE Made mostly from lipids and proteins
MESOSOME Folded region of plasma membrane, increases surface area for enzymes
CELL WALL Made of murein/Peptidoglycan
CAPSULE Thick polysaccharide layer, sticks cells together, food reserve, protection against outside chemicals and phagocytosis
FLAGELLA Helical shaped tail for movement, embedded in a membrane, driven by a proton gradient

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38
Q

How does bacteria divide

A

By binary fission every 20 minutes
Also divide asexually - no division of genes

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39
Q

Describe the Gram stain

A

Gram positive bacteria have thick walls and purple stain
Gram negative bacteria have thin walls with an outer lipid layer and stain pink

40
Q

Describe the process of ultracentrifugation

A

The fragments in the filtered homogenate are separated in a centrifuge. This spins tubes of homogenate at a very high speed to create a centrifugal force.
1-The tube of filtrate is placed in the centrifuge and spun at a slow speed
2- The heaviest organelles, the nuclei are forced to the bottom of the tube, forming a pellet
3- The supernatant is removed, leaving the sediment of nuclei
4- The supernatant is transferred to another tube and spun at a faster speed than before
5- The next heaviest organelles, the mitochondria, are forced to the bottom of the tube, forming a pellet
6- This process continues so as each increase in speed, the next heaviest organelle is sedimented and separated out

41
Q

What is the order of pellets in cell fractionation

A

Nuclei Never
Chloroplast(If using plant) Choke
Mitochondria My
Lysosomes Lovely
Endoplasmic reticulum Energetic
Ribosomes Rabbit

42
Q

What are the differences between DNA in the nucleus and Prokaryote

A

Linear, histones, no plasmid, longer, introns
Circular, no histones, plasmid, shorter, no introns

43
Q

Viruses are accelular(not cells) they are…

A

Nucleic acid surrounded by proteins

44
Q

Viruses are not prokaryotic/eukaryotic, they are…

A

A type of obligate intracellular parasite

45
Q

What is smaller. Bacteria or Virus and give a size

A

Viruses are smaller than bacteria (<0.1 micrometres)

46
Q

What is a bacteriophage

A

A virus that can invade bacteria

47
Q

What are the 5 parts of HIV and explain each of them

A

ATTACHMENT PROTEINS Allows virus to attach to host cell
VIRAL ENVELOPE Outer membrane and contains attachment proteins, made out of a membrane taken by host’s cell membrane
CAPSID Protein coat containing nucleic acid
RNA Genetic information
REVERSE TRANSCRIPTASE Enzyme for replication

48
Q

Why are viruses not killed by antibiotics

A

They replicate inside cells so it is difficult to destroy the virus without harming the host cell it is in
Viruses have different mechanisms and chemical reactions and no cell walls

49
Q

Define magnification and resolution
What does the resolution depend on for an optical and electron microscope

A

How much times larger the image is compared to the object
The minimum distance needed betweeb 2 objects for them to appear as two seperate objects
Resolution of an optical microscope depends on the wavelength of light
Resolution of an electron microscope depends on the wavelength of beams of electrons

50
Q

Difference between optical microscope and electron microscope

A

-A beam of light is condensed to create an image / A beam of electrons is condensed to create an image (electromagnet used to condense the beam of electrons)
-Lower resolution due to light having a longer wavelength/ higher resolution due to electrons having a shorter wavelength
-Lower magnification / higher magnification
-Coloured images / Black and white images
-View living cells/ Sample must be in a vacuum so can’t view living cells
-Optical microscope is a time consuming process to prepare slides
-Optical microscope can’t view smaller organelles (Ribosomes and ER)

51
Q

Explain the Optical microscope
What is the max resolution and magnification

A

Light passes through the specimen and is projected through glass lenses where the image is magnified
0.2 micrometers
×1500(useful until resolution stays clear)

52
Q

In an optical microscope, explain why you stain it, why the specimen should be thin, use an absorbent paper, use a cover slip

A

Stain it - Use potassium iodide to make certain structures visible
Specimen should be thin - single layer of cells, light can pass through
Use an absorbent paper - To absorb excess iodine
Use a cover slip - To remove air bubbles/excess iodine on specimen

53
Q

Explain how you prepare a temporary mount (temporary coverslip)

A

-Use a pippete to place a drop of water onto the slide (keeps Tissue flat)
-Use tweezers to place a thin layer of the specimen on the slide
-Lower the coverslip using a mounted needle (protects the specimen and prevents airbubbles)

54
Q

What is the eyepiece graticule
What is a stage micrometer and how long are the subdivisions

A

Scale in the eyepiece
A slide with a scale etched on - 10 micrometers

55
Q

What are the two types of electron microscopes
Why must these specimen be in a vacuum

A

TEM Transmission Electron Microscope
SEM Scanning Electron Microscope
Electrons are absorbed by the air so do not reach specimen and do not form an image

56
Q

Describe Transmission Electron Microscope

A

-Thin specimens are stained fo allow electrons to pass through
-Some beams of electrons pass through the specimen, some is absorbed by the specimen, darker parts of the cells is where more electrons have been absorbed as it is harder for electrons to pass through
-2D image
-Max magnification is 250 000×
-Max resolution is 2nm

57
Q

Describe Scanning Electron Microscope

A

-Specimen does not need to be thin as electrons are not passing through specimen
-Electrons are beamed onto the surface and are reflected and scattered in different ways depending on the depth. This produces a 3D image
-Specimen is coated with a thin layer of metal
-Max magnification is 100 000×
-Max resolution is 3 to 20 nm

58
Q

What are the advantages and disadvantages of electron microscopes

A

ADVANTAGES:
- Higher resolution as electron beam’s wavelength is shorter than light (smaller organelles can be seen)
-SEM produces 3D images
DISADVANTAGES
-Specimens must be in a vacuum so no living specimen can be seen (electrons are deflected when then hit gasmaking it difficult for the electron beam to focus)
-Images are in black and white
-Complex staining process as it may contain artefacts
- TEM specimen must be thin to allow electrons to penetrate
- TEM Produces flat, 2D images(can be overcame by taking a series of sections)
- SEM has lower resolution than TEM (still better than OM)

59
Q

Define artefact
Give some examples
Why does this happen

A

Images seen under a microscope that are not part of the cell
Dust, air bubbles, fingerprints, folds
Occurs during the incorrect preparation of specimen

60
Q

Explain the step done before homogenisation and ultracentrifugation

A

-Tissue is minced and placed in cold buffered, isotonic solution

61
Q

What is differential centrifugation

A

Process involving centrifuging at different speeds

62
Q

Why is the plasma membrane described as a fluid mosaic model

A

Due to the movement and mixture of the phospholipids, proteins, glycoproteins, glycolipids and carbohydrates it’s made from

63
Q

What are a few function of plasma membrane

A

Controls the movement of substance in and out of the cell
Isolates organelles and enzymes
Internal transport system
Provides surface for biochemical reactions
Allows cell to change shapes

64
Q

In a phospholipid bilayer, where do the tails point

A

Tails point to the centre of the membrane

65
Q

What is the function of cholesterol in the fluid mosaic model
At high temperatures, what us the fluidity like

A

Binds tails together which restricts the lateral movements of molecules on the membrane, less fluid and more rigid but not completely rigid
At high temperatures, there is low fluidity to prevent water and dissolved ions from leaking out the cell(prevents cell from dehydration and bursting)

66
Q

How are the proteins in a plasma membrane embedded in it
Explained extrinsic and intrinsic(how much they span across the bilayer)

A

In a random arrangement
Extrinsic: does not extend completely across the membrane
Intrinsic: spans across one side of the bilayer to the other

67
Q

Explain extrinsic proteins and intrinsic proteins

A

EXTRINSIC PROTEINS: Provide mechanical support, function is cell recognition such as receptors
INTRINSIC PROTEINS: Protein carriers or channel proteins transport molecules across the membrane

68
Q

What is another name for extrinsic and intrinsic proteins

A

Extrinsic - Peripheral
Intrinsic - Integral

69
Q

Define glycoproteins and glycolipids

A

GLYCOPROTEINS: Carbohydrate attached to protein
GLYCOLIPIDS: Carbohydrate attached to lipid

70
Q

Explain protein channels and carrier proteins

A

Protein channels form tubed that fill with water to allow water soluble ions to diffuse
Highly selective channels, only open when the specific ion is present and binds to the protein
Carrier proteins bind to larger modelcules(e.g. amino acids, glucose) which causes the protein to change shape and transport then to the other side of the membrane and release it

71
Q

What are glycoproteins and glycolipids involved in

A

Cell adhesion(attaching cells to eachother)
Cell recongition(allows cells to recognise one another)
Cell signalling(communication between cells)

72
Q

Explain the partially permeable membrane

A

Lipid soluble molecules and very small molecules can diffuse through the plasma membrane
Water soluble substances and large molecules cannot pass through the membrane

73
Q

Explain simple diffusion

A

Net movement of molecules from an area of high concentration to low concentration until equilibrium is reached
This process does not reuire ATP
Form of passive transport

74
Q

Why do molecules in simple diffusion have kinetic energy

A

To allow them to constantly move in fluids

75
Q

What are factors that affect diffusion

A

Concentration gradient: The greater the difference in gradient, the faster the rate of diffusion
Surface area: The larger the surface area, the faster the rate of diffusion
Length and thickness of diffusion pathway: He thinner or shorter the exchange surface the faster the rate of diffusion

76
Q

Explain facilitated diffusion

A

Passive process, doesn’t require ATP
Proteins are used to transport molecules such as ions and polar molecules that can’t diffuse
They only occur at specific points on the plasma membrane

77
Q

Define active transport
What two things does active transport require
What is one important fact about active transport

A

The movement of molecules from an area of low concentration to an area of high concentration using ATP and a carrier protein
It is highly selective

78
Q

Explain the steps for active transport

A

-Molecules binds to receptors on specific carrier proteins
-ATP binds to the carrier protein on the inside of the cell
-ATP is hydrolysed into ADP and a Phosphate
-This causes the carrier protein to change shape and the molecule will be released on the other side of the membrane
-The Phosphate and ADP is released from the protein, causing the protein to return to its original configuration
-Phosphate and ADP combine to make ATP during respiration

79
Q

What does passive transport rely on

A

Random movement of particles and diffusion

80
Q

What are two types of transport

A

Passive and Active

81
Q

What features prevent particles from passing through the membrane via simple diffusion

A

Polar, Charged, Large, Hydrophilic

82
Q

Give 4 adaptations that maximise the rate of diffusion

A

Maintaining a steep concentration gradient
Shortest possible diffusion pathway
Higher surface area to volume ratio(more folds in membrane)
High number of transport proteins in a given area

83
Q

Explain how water potential affects rate of diffusion

A

The greater the difference in water potential, the steeper the concentration gradient so the faster the rate of diffusion

84
Q

Explain the process of co transport

A

A transport protein binds to the first moelcule and an ATP
The transport protein hydrolysis ATP into ADP and one Phosphate ion. This causes the transport protein to chnage shape so the molecule is released on the other side of the membrane. The shape change reveals a second binding site in the protein where the second particle binds. The Phosphate ion is released causing the protein to return to its original shape. The second particle is then released on the other side of the membrane

85
Q

Not all carrier proteins that carry out co transport have ATP binding sites. Instead, some Co transport carrier proteins…

A

Transport one moelcule down the concentration gradient and use the resulting energy to move a second particle against its concentration gradient

86
Q

Define osmosis

A

The movement of water moelcules from an area of higher water potential to lower water potential through a partially permeable membrane

87
Q

What is water potential
What is the units
What is the symbol

A

The pressure created by water molecules
Kilopascals

88
Q

What is the water potential of pure water
When solute is dissolved in water, does the water potential become positive or negative

A

0
Negative

89
Q

What is the relationship between water potential and amount of solute dissolved

A

The more negative the water potential, the more solute dissolved in it

90
Q

Define hypertonic, hypotonic and isotonic

A

Hypertonic: A solution with less water and more solute
Hypotonic: A solution with more solute and less water
Isotonic: A solution with the same amount of water and solute

91
Q

What happnes to animal cells and plant cells when placed in pure water

A

Animal cells will eventually burst(haemolysed)
Plant cell, cytoplasm and vacoule push against the cell wall which stops the cell from getting any larger (turgid)

92
Q

What happens to animal cells and plant cells when placed in sugar solution

A

Animal cells, cell content shrinks and membrane wrinkles(flaccid)
Plant cells, Cytoplasm and vacuole shrinks and membrane pulls away from the cell wall(plasmolysed)

93
Q

When a plant cell is placed in a sugar solution, what is present in between the cell wall and cell membrane and why?

A

Sugar solutions is found as the cell wall isn’t partially permeable

94
Q

Explain the produces in sodium potassium pump

A

1)Sodium ions are actively transported out of the epithelial cells into the blood through a sodium potassium pump(potassium ions are actively transported in)
2) Now, there is a higher concentration of sodium ions in the lumen of the intestine than inside the epithelial cell
3) This causes sodium ions to diffuse into the epithelial cell through a co transport protein
4) As this happens, they carry a glucose/amino acid molecule into the epithelial cell against the concentration gradient
5) The glucose/amino acid molecule is brought into the blood by sodium ions through facilitated diffusion using carrier proteins

95
Q

Uncertainty is ± ___________

A

Uncertainty is ± half the resolution

96
Q

Starch grains (from sugars in photosynthesis) are found in…

A

Stroma/Seeds/Storage organs(e.g.potatoes)

Biology Paper 1/2 (3 decks)

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