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aqa biology > 3.2 Cells | COMPLETE > Flashcards

3.2 Cells | COMPLETE Flashcards

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1
Q

3.2.1
what are the three types of microscopes?

A

transmission-electron
light
scanning-electron

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2
Q

3.2.1
what is good and bad about a TE microscope?

A

most powerful magnification
information on element and compound

dead specimen

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3
Q

3.2.1
what is good and bad about a SE microscope?

A

3D image

dead specimen

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4
Q

3.2.1
what is good and bad about a light microscope?

A

living and dead specimen

2D image

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5
Q

3.2.1
why can ribosomes be seen with electron microscopes and not light microscopes?

A

electrons are thinner the the wavelengths of light so electrons can recognise them but light is too fat to register it

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6
Q

3.2.1
what is the difference between eukaryotic and prokaryotic cells?

A

eukaryotic have membrane-bound organelle, prokaryotic don’t

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7
Q

3.2.1
what organelle are in animal cells?

A

cell-surface membrane
nucleus
mitochondria
golgi apparatus
vesicles
lysosomes
ribosomes
rough endoplasmic reticulum
smooth endoplasmic reticulum

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8
Q

3.2.1
what organelle are in plant cells?

A

cell-surface membrane
nucleus
mitochondria
chloroplasts
golgi apparatus
vesicles
ribosomes
rough endoplasmic reticulum
smooth endoplasmic reticulum
cell wall
vacuole

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9
Q

3.2.1
what does the golgi apparatus do?
(five)

A

Add carbohydrates to proteins to form glycoproteins​
Produce secretory enzymes e.g. pancreas​
Secrete carbohydrates e.g. cell walls​
Transport, modify and store lipids​
Form lysosomes​

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10
Q

3.2.1
what does the smooth endoplasmic reticulum do?
(four)

A

Lacks ribosomes​
Synthesise, process, store and transport lipids​
Synthesise, process, store and transport carbohydrates.​
Lots found in liver and​ secretory cells.​ e.g. epithelial cells

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11
Q

3.2.1
what does the rough endoplasmic reticulum do?
(two)

A

the synthesis and processing (folding) of proteins and glycoproteins.​
provide a pathway for the transport of materials, especially proteins, throughout the cell.​

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12
Q

3.2.1
what is cell theory?

A

cells are the smallest unit capable of independent life
cells are the basic unit of life
cells arise from other cells via division
cells contain information which acts as instructions for growth

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13
Q

3.2.1.2
what organelle do prokaryotic cells have?

A

cytoplasm (that lacks membrane-bound organelles)
ribosomes
plasmid DNA
chromosomal DNA
cell wall (contains murein, a glycoprotein)
slime capsule
one or more flagella.

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14
Q

3.2.1.2
what do viruses contain?

A

attachment proteins
capsid
reverse transcriptase
lipid membrane
matrix
DNA/RNA

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15
Q

3.2.1.2
TRUE OR FALSE
viruses are living

A

FALSE
they don’t meet the criteria to be classed as living

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16
Q

3.2.1.3
what is cell fractionation?

A

cells are broken up and the different organelle are separated out

before this process the tissue is placed in a solution that is cold, buffered and has the same water potential as the sample

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17
Q

3.2.1.3
why does a solution have to be cold for cell fractionation?

A

to reduce enzyme activity that might break down the organelles

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18
Q

3.2.1.3
why does a solution have to have the same water potential for cell fractionation?

A

prevent cell from bursting or shrinking due to osmosis

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19
Q

3.2.1.3
why does a solution have to be buffered for cell fractionation?

A

the pH does not fluctuate which might change the structure of the organelles or affect enzyme functions

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20
Q

3.2.1.3
what are the two stages of cell fractionation?

A

homogenisation
ultracentrifugation

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21
Q

3.2.1.3
what is the blended sample called?

A

homogenate

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22
Q

3.2.1.3
in what order do the organelle become pellets during centrifugation

A

nuclei -> mitochondria (+chloroplasts) -> microsomes -> ribosomes

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23
Q

3.2.1.3
define homogenisation

A

cells are broken up by a homogeniser to release organelles from the cell to produce a homogenate then FILTERED to remove large debris

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24
Q

3.2.1.3
define ultracentrifugation

A

tubes of filtered homogenate are spun at a very high speed in order to create a centrifugal force and to separate fragments of the homogenate in a centrifuge

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25
Q

3.2.1.3
what is the formula for magnification?

A

image size / actual size

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26
Q

3.2.2
what does mitosis produce?

A

two genetically identical daughter cells

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27
Q

3.2.2
what are the stages in the cell cycle in order?

A

G1
S
G2
mitosis
cytokinesis

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28
Q

3.2.2
what happens in G1?

A

organelles are duplicated

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29
Q

3.2.2
what happens in S?

A

DNA is replicated

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30
Q

3.2.2
what happens G2?

A

DNA is checked

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31
Q

3.2.2
what happens during interphase?

A

G1
S
G2

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32
Q

3.2.2
what happens in prophase?

A

chromosomes condense
nucleolus dissolves
centrioles move further apart
each centrioles form spindle fibres

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33
Q

3.2.2
what happens in metaphase?

A

chromatids join by the centromere
centromere that some microtubules from the poles are attached and the chromosomes are pulled along the spindle fibres arranging at the equator of the cell

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34
Q

3.2.2
what happens in anaphase?

A

centromere divides into two
spindle fibres pull the individual chromatids

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35
Q

3.2.2
what happens in telophase and cytokinesis?

A

chromosomes reach their respective poles
spindle fibres disintegrate and the nuclear envelope and nucleolus reform
the cytoplasm divides in cytokinesis

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36
Q

3.2.2
what is a centromere?

A

appears as a constricted region of a chromosome
plays a key role in helping the cell divide up its DNA during division
it is the region where the cell’s spindle fibres attach

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37
Q

3.2.2
TRUE OR FALSE
mitosis a controlled process

A

TRUE

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38
Q

3.2.2
what causes cancer?

A

uncontrollable cell division which results in a tumour

39
Q

3.2.2
TRUE OR FALSE
viruses undergo cell division

A

FALSE
viruses use host cell ribosomes to duplicate

40
Q

3.2.2
how do prokaryotic cells duplicate and describe the process?

A

binary fission

replication of DNA and plasmids
division of cytoplasm
produces two daughter cells each with a single copy of circular DNA and a variable number of copies of plasmids

41
Q

3.2.2
TRUE OR FALSE
in multicellular organisms all the cells retain the ability to undergo division

A

FALSE
not all cells can

e.g. red blood cells and neurons

42
Q

3.2.3
what is simple diffusion?
(four points)

A

> the net movement of particles down a concentration gradient, from a high concentration to low concentration
through a membrane
without any help from transport proteins
small noncharged molecules or lipid soluble molecules

43
Q

3.2.3
what is facilitated diffusion?
(four points)

A

> the movement of particles down a concentration gradient, from a high concentration to low concentration
through a membrane
involves the use of carrier and channel proteins
allows polar and charged molecules, such as carbohydrates, amino acids, nucleosides, and ions

44
Q

3.2.3
what is osmosis?

A

the net movement of water molecules through a semi-permeable membrane, from a region of high water potential to a region of low water potential.

45
Q

3.2.3
which proteins are used in facilitated diffusion?

A

carrier and channel proteins

46
Q

3.2.3
why can’t amino acids move via simple diffusion

A

they are not lipid-soluble so they can’t pass through the phospholipid membrane

47
Q

3.2.3
which type of diffusion requires ATP and why?

A

facilitated
because the carrier proteins need to do the flip-flop movement

48
Q

3.2.3
what is active transport?

A

the movement of molecules against a concentration gradient, from a region of low concentration to a region of high concentration. It is an active process using ATP

49
Q

3.2.3
which proteins are used in active transport?

A

carrier and channel proteins

50
Q

3.2.3
why does active transport require ATP?

A

it is going against a concentration gradient

it is an active process

51
Q

3.2.3
what is co-transport?

A

the coupled movement of substances across a cell membrane via a carrier protein. It involves a combination of facilitated diffusion and active transport.

52
Q

3.2.3
give an example of co-transport

A

sodium and potassium pump in epithelial cells on the lining of the lumen of the ileum

53
Q

3.2.3
what are microvilli and what is their role?

A

they are hair-like structures on the surfaces of epithelial cells
they increase surfaces area

54
Q

3.2.3
what adaptations do epithelial cells have?

A

many mitochondria
microvilli

55
Q

3.2.4
what is a pathogen?

A

any organism which can cause disease to its host

56
Q

3.2.4
how do we stop pathogens from entering our body generally?

A

skin
hydrochloric acid in the stomach
phagocytes
mucus
lysosomes in tears

57
Q

3.2.4
define non-specific defence mechanisms

A

they work against a wide variety of pathogens
they are physical barriers to infection and always work in the same way​

58
Q

3.2.4
what is phagocytosis?
- definition not steps -

A

a process wherein a cell binds to the item it wants to engulf on the cell surface and draws the item inward while engulfing around it

59
Q

3.2.4
what type of immunity is phagocytosis?

A

innate
non-specific

60
Q

3.2.4
what type of immunity is B-Lymphocytes?

A

humoral
specific

61
Q

3.2.4
what type of immunity is T-Lymphocytes?

A

cell-mediated/cellular
specific

62
Q

3.2.4
define antigen

A

unique glycoproteins present on the surface of cells, which trigger an immune response

63
Q

3.2.4
what are the steps of phagocytosis?
(five steps)

A

> pathogen recognised as foreign – pathogen is antigenic
pathogen attached to phagocyte by antibody and surface receptors​
engulfed by phagocyte invagination of plasma cell membrane takes place to form a phagosome
lysosomes fuse to phagosome
digest pathogen – harmless products removed (egested / excreted) or used by phagocyte​

64
Q

3.2.4
what is a phagosome?

A

a membrane bound vesicle containing the pathogen

65
Q

3.2.4
what do lysosomes contain?

A

hydrolytic enzymes

66
Q

3.2.4
what are the key words for phagocytosis?
(six)

A

pathogen​
antigens​
invagination​
phagosome​
lysosome​
hydrolysis

67
Q

3.2.4
where are T-Cells made and mature?

A

made in bone marrow
mature in the thymus

68
Q

3.2.4
where are B-Cells made and mature?

A

made in the bone marrow
mature in the bone marrow

69
Q

3.2.4
what do T-Cells do?

A

carries out the cell-mediated/cellular response
this means they recognise and destroy any abnormal or foreign cells

70
Q

3.2.4
what do B-Cells do?

A

carries out the humoral response
this means they are responsible for the production of antibodies

71
Q

3.2.4
what do T-Cells respond to?

A

virus infected cells
cancer cells
non-self matter
transplanted material

72
Q

3.2.4
what are antigen-presenting cells?

A

when phagocytes digest pathogens they display antigens on their surface
infected/abnormal body cells do this as well

73
Q

3.2.4
TRUE OR FALSE

There are 1000s of types of T cell, each having a different type of T cell receptor.
Each T cell can recognise and attack many type of antigen

A

FLASE

There are MILLIONS of types of T cell, each having a different type of T cell receptor
Each T cell can ONLY recognise and attack ONE type of antigen

74
Q

3.2.4
what is the process of the cell-mediated/cellular response?
(five/six)

A

pathogens infect cells or are ingested by phagocytes

phagocytes/cells present antigens on the cell surface membrane from the pathogen using the MHC

the specific active site of the MHC binds to the Th - phagocyte secretes cytokines

the cell activates and undergoes mitosis to replicate

this stimulates B-Cells to divide and multiple by mitosis and to produce antibodies and, phagocytes do more

this also activates cytotoxic T-Cells to produce cytokines and, produce B-Lymphocyte Memory Cells

75
Q

3.2.4
what does MHC stand for?

A

Major Histocompatibility Complex

76
Q

3.2.4
what does Th stand for?

A

helper T lymphocytes

77
Q

3.2.4
what are B-Lymphocyte Memory Cells?

A

they are long lasting cells that stay in our blood and recognise select pathogens and can ‘kill’ it in the next infection/contact

78
Q

3.2.4
what is the humoral response?
(four)

A

When an foreign antigen enters the blood it combines with a few B-lymphocytes

Which then divide rapidly through mitosis forming a clone of plasma cells.

These then produce mainly antibodies but also memory cells.

The memory cells can live for large periods of time, sometime even for life.

79
Q

3.2.4
what is an antibody made up from?

A

4 polypeptide chains -> 2 heavy chains and 2 light chains
variable region
constant region
hinge
antigen-binding site

80
Q

3.2.4
compare the shape of the heavy and light chain on an antibody?

A

the heavy chain is longer than the light chain

81
Q

3.2.4
what is neutralisation?

A

Antibodies can bind to antigenic epitopes present on viruses which are emerging from virus infected cells.

These viruses are then inactivated and are unable to infect further healthy cells. ​

Antibodies can also neutralise toxins in the same way by binding to them as they are produced by bacteria. ​

82
Q

3.2.4
what is complement recruitment?
(three)

A

a system of plasma proteins that can be activated directly by pathogens or indirectly by pathogen-bound antibody

leading to a cascade of reactions that occurs on the surface of pathogens and generates active components with various effector functions

which help clear infection by promoting inflammation and attacking the cell membrane of the pathogen.​

83
Q

3.2.4
what are monoclonal antibodies?

A

antibodies produced from a single group of genetically identical B-cells (plasma cells)

84
Q

3.2.4
what is the structure of monoclonal antibodies?

A

identical in structure (clones)

same tertiary shape because they have the same primary sequence of amino acids

85
Q

3.2.4
what can we use monoclonal antibodies for?

A

medical testing

targeted medication

86
Q

3.2.4
how do we make monoclonal antibodies?
(six)

A

Mouse exposed to antigen / pathogen​

Plasma cells produce antibodies for the antigen​

Plasma cells are fused together with tumour cells (rapidly dividing) using detergent forming a Hybridoma​

Hybridoma cells are then cloned producing multiple clones.​

Clones are tested for antibody production​

Clones producing the correct antibody are cultured in a growth medium and the antibody is extracted​

87
Q

3.2.4
what are the ethical implications of the production of monoclonal antibodies?
(three)

A

cancer is deliberately induced in mice to produce both tumour and plasma cells. (Ethics of animal welfare)​

there have been deaths so patients must give informed consent

drug testing dangers (e.g. organ failure) raises issues around how drug trails are conducted.​

88
Q

3.2.4
how does a pregnancy test work?
(six)

A

Application area contains mobile hCG antibodies bound to coloured dye​

Urine applied to application area​

If hCG is present it binds to the mobile antibodies carrying a coloured dye forming an antigen-antibody complex.​

The antibodies then move up the absorbent strip by capillary action

hCG then binds to immobilised hCG antibodies in the test strip at point C forming a blue line as the dye concentrates above the immobilised antibodies showing a +ve result.​

Excess mobile antibodies or mobile antibodies which have not bound to hCG will bind to a second area (point D) containing immobilised antibodies/receptors for the constant region of the mobile antibody, this shows the test strip has worked.​

89
Q

3.2.4
what does hCG stand for?

A

human chorionic gonadotropin

90
Q

3.2.4
where is hCG produced in the body?

A

the placenta

91
Q

3.2.4
what is direct monoclonal antibody therapy?

A

Antibodies block receptors that stimulate growth – cell cycle/mitosis is prevented​

92
Q

3.2.4
what is in-direct monoclonal antibody therapy?

A

Cytotoxic/radioactive drug is attached to antibody​

When antibody binds to cancer cell, the drug kills them​

93
Q

3.2.4
what are the stages of ELISA testing?
(four/eight)

A

HIV antigen is bound to the bottom of the reaction vessel
WASH OUT
Blood plasma sample added
WASH OUT
Secondary antibody added
WASH OUT
Substrate added and if HIV is present the enzyme will react with the substrate forming a coloured product

use a colorimeter to determine how much colour was produced

94
Q

3.2.4
what does ELISA stand for?

A

enzyme-linked immunosorbent assay

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