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aqa biology > 3.2 Cells | COMPLETE > Flashcards

3.2 Cells | COMPLETE Flashcards

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
3.2.1.3 what is the formula for magnification?
image size / actual size
26
3.2.2 what does mitosis produce?
two genetically identical daughter cells
27
3.2.2 what are the stages in the cell cycle in order?
G1 S G2 mitosis cytokinesis
28
3.2.2 what happens in G1?
organelles are duplicated
29
3.2.2 what happens in S?
DNA is replicated
30
3.2.2 what happens G2?
DNA is checked
31
3.2.2 what happens during interphase?
G1 S G2
32
3.2.2 what happens in prophase?
chromosomes condense nucleolus dissolves centrioles move further apart each centrioles form spindle fibres
33
3.2.2 what happens in metaphase?
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
34
3.2.2 what happens in anaphase?
centromere divides into two spindle fibres pull the individual chromatids
35
3.2.2 what happens in telophase and cytokinesis?
chromosomes reach their respective poles spindle fibres disintegrate and the nuclear envelope and nucleolus reform the cytoplasm divides in cytokinesis
36
3.2.2 what is a centromere?
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
37
3.2.2 TRUE OR FALSE mitosis a controlled process
TRUE
38
3.2.2 what causes cancer?
uncontrollable cell division which results in a tumour
39
3.2.2 TRUE OR FALSE viruses undergo cell division
FALSE viruses use host cell ribosomes to duplicate
40
3.2.2 how do prokaryotic cells duplicate and describe the process?
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
3.2.2 TRUE OR FALSE in multicellular organisms all the cells retain the ability to undergo division
FALSE not all cells can e.g. red blood cells and neurons
42
3.2.3 what is simple diffusion? (four points)
> 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
3.2.3 what is facilitated diffusion? (four points)
> 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
3.2.3 what is osmosis?
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
3.2.3 which proteins are used in facilitated diffusion?
carrier and channel proteins
46
3.2.3 why can't amino acids move via simple diffusion
they are not lipid-soluble so they can't pass through the phospholipid membrane
47
3.2.3 which type of diffusion requires ATP and why?
facilitated because the carrier proteins need to do the flip-flop movement
48
3.2.3 what is active transport?
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
3.2.3 which proteins are used in active transport?
carrier and channel proteins
50
3.2.3 why does active transport require ATP?
it is going against a concentration gradient it is an active process
51
3.2.3 what is co-transport?
the coupled movement of substances across a cell membrane via a carrier protein. It involves a combination of facilitated diffusion and active transport.
52
3.2.3 give an example of co-transport
sodium and potassium pump in epithelial cells on the lining of the lumen of the ileum
53
3.2.3 what are microvilli and what is their role?
they are hair-like structures on the surfaces of epithelial cells they increase surfaces area
54
3.2.3 what adaptations do epithelial cells have?
many mitochondria microvilli
55
3.2.4 what is a pathogen?
any organism which can cause disease to its host
56
3.2.4 how do we stop pathogens from entering our body generally?
skin hydrochloric acid in the stomach phagocytes mucus lysosomes in tears
57
3.2.4 define non-specific defence mechanisms
they work against a wide variety of pathogens they are physical barriers to infection and always work in the same way​
58
3.2.4 what is phagocytosis? - definition not steps -
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
3.2.4 what type of immunity is phagocytosis?
innate non-specific
60
3.2.4 what type of immunity is B-Lymphocytes?
humoral specific
61
3.2.4 what type of immunity is T-Lymphocytes?
cell-mediated/cellular specific
62
3.2.4 define antigen
unique glycoproteins present on the surface of cells, which trigger an immune response
63
3.2.4 what are the steps of phagocytosis? (five steps)
> 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
3.2.4 what is a phagosome?
a membrane bound vesicle containing the pathogen
65
3.2.4 what do lysosomes contain?
hydrolytic enzymes
66
3.2.4 what are the key words for phagocytosis? (six)
pathogen​ antigens​ invagination​ phagosome​ lysosome​ hydrolysis
67
3.2.4 where are T-Cells made and mature?
made in bone marrow mature in the thymus
68
3.2.4 where are B-Cells made and mature?
made in the bone marrow mature in the bone marrow
69
3.2.4 what do T-Cells do?
carries out the cell-mediated/cellular response this means they recognise and destroy any abnormal or foreign cells
70
3.2.4 what do B-Cells do?
carries out the humoral response this means they are responsible for the production of antibodies
71
3.2.4 what do T-Cells respond to?
virus infected cells cancer cells non-self matter transplanted material
72
3.2.4 what are antigen-presenting cells?
when phagocytes digest pathogens they display antigens on their surface infected/abnormal body cells do this as well
73
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
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
3.2.4 what is the process of the cell-mediated/cellular response? (five/six)
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
3.2.4 what does MHC stand for?
Major Histocompatibility Complex
76
3.2.4 what does Th stand for?
helper T lymphocytes
77
3.2.4 what are B-Lymphocyte Memory Cells?
they are long lasting cells that stay in our blood and recognise select pathogens and can 'kill' it in the next infection/contact
78
3.2.4 what is the humoral response? (four)
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
3.2.4 what is an antibody made up from?
4 polypeptide chains -> 2 heavy chains and 2 light chains variable region constant region hinge antigen-binding site
80
3.2.4 compare the shape of the heavy and light chain on an antibody?
the heavy chain is longer than the light chain
81
3.2.4 what is neutralisation?
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
3.2.4 what is complement recruitment? (three)
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
3.2.4 what are monoclonal antibodies?
antibodies produced from a single group of genetically identical B-cells (plasma cells)
84
3.2.4 what is the structure of monoclonal antibodies?
identical in structure (clones) same tertiary shape because they have the same primary sequence of amino acids
85
3.2.4 what can we use monoclonal antibodies for?
medical testing targeted medication
86
3.2.4 how do we make monoclonal antibodies? (six)
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
3.2.4 what are the ethical implications of the production of monoclonal antibodies? (three)
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
3.2.4 how does a pregnancy test work? (six)
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
3.2.4 what does hCG stand for?
human chorionic gonadotropin
90
3.2.4 where is hCG produced in the body?
the placenta
91
3.2.4 what is direct monoclonal antibody therapy?
Antibodies block receptors that stimulate growth – cell cycle/mitosis is prevented​
92
3.2.4 what is in-direct monoclonal antibody therapy?
Cytotoxic/radioactive drug is attached to antibody​ When antibody binds to cancer cell, the drug kills them​
93
3.2.4 what are the stages of ELISA testing? (four/eight)
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
3.2.4 what does ELISA stand for?
enzyme-linked immunosorbent assay

aqa biology (9 decks)

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