topic 2 Flashcards
(116 cards)
1
Q
what is the structure of the cell surface membrane?
A
phospholipid bilayer
2
Q
what is the function of the cell surface membrane?
A
controls entry and exit into the cell
3
Q
what is the structure of the nucleus?
A
nuclear envelope with a double membrane, nuclear pores, nucleoplasm, nucleolus, chromosomes
4
Q
what is the function of the nucleus?
A
the site of DNA replication and transcription
5
Q
what is the structure of the mitochondria?
A
a double membrane, inner membrane is the cristae, contains a fluid matrix and loops of DNA
6
Q
what is the function of the mitochondria?
A
to produce energy
7
Q
what is the structure of the chloroplasts?
A
double membranes, thylakoid membranes, stroma which contains enzymes for photosynthesis
8
Q
what is the function of the chloroplasts?
A
contains chlorophyll for photosynthesis
9
Q
what is the structure of the vacuole?
A
fluid filled tonoplast
10
Q
what is the function of the vacuole?
A
to keep the cell turgid, temporary store
11
Q
what is the structure of the Golgi apparatus/ vesicles?
A
folded membranes
12
Q
what is the function of the Golgi apparatus/ vesicles?
A
to form glycoproteins/ secretory enzymes/ lysozymes, and transport/storage of lipids
13
Q
what is the structure of lysosomes?
A
bags of digestive enzymes
14
Q
what is the function of lysosomes?
A
to hydrolyse phagocytic cells, break down dead cells/organelles, exocytosis
15
Q
what is the structure of ribosomes?
A
protein and rRNA subunits
16
Q
what is function of ribosomes?
A
protein synthesis
17
Q
what is the structure of the rough endoplasmic reticulum?
A
folded membrane with ribosomes
18
Q
what is the structure of the smooth endoplasmic reticulum?
A
folded membrane
19
Q
what is the role of the rough/smooth endoplasmic reticulum?
A
protein synthesis, synthesise and store lipids and carbohydrates
20
Q
what is the structure of the cell wall?
A
made of cellulose/chitin
21
Q
what is the function of the cell wall?
A
structural strength
22
Q
how is a prokaryotic cell different to a eukaryotic cell?
A
smaller no membrane bound organelles smaller ribosomes no nucleus cell wall made of murein may have plasmids/capsule/flagella
23
Q
what is magnification?
A
how many times larger an image is compared to an object
24
Q
what is resolution?
A
ability to distinguish between 2 objects
25
what is an optical microscope?
light beam, poor resolution, low magnification, colour, can use living samples
26
what is an electron microscope?
electron beam, high resolution, high magnification, black and white, vacuum so non living
27
how does a TEM microscope work?
beam through a sample, absorbed appears darker, thin specimens, 2D image
28
how does a SEM microscope work?
scan a beam of electrons, scattered and collected in a cathode ray tube, 3D image
29
what does an eyepiece graticule do?
measures the size of objects that you are viewing under the microscope
30
what is a stage micrometer?
glass slide that you place on the stage
31
how do you use an eyepiece graticule ?
1) line up stage micrometer and eye piece graticule when looking through the eye piece
2) count how many divisions on the graticule fit onto one division of the micrometer scale
3) each division= 10 um, so use it to work out what one division on the eyepiece graticule is worth
32
how do you prepare a slide for a microscope?
place a drop of water on the slide, use tweezers to place a thin section of the sample on top, add a drop of the stain, carefully tilt on the cover slip
33
what is the purpose of cell fractionation?
to look at individual organelles
34
what solution are the organelles kept in?
a cold, isotonic, buffered solution
35
why is the solution cold?
reduces enzyme activity to prevent damage to organelles
36
why is the solution isotonic?
the same water potential prevents organelles being damaged by osmosis
37
why is the solution buffered?
prevents changes in pH which could damage organelles
38
what happens in homogenisation?
cells are broken down and blended in solution
39
why do you filter the solution?
to remove large cell debris
40
why do you use ultracentrifugation?
the filtered solution is spun so it separates according to density
41
what is the pellet?
thick sediment at the bottom
42
what is the supernatant?
liquid containing the rest of the organelles
43
what is the order of the density of organelles? (heaviest to lightest)
nuclei, chloroplasts and mitochondria, lysosomes and endoplasmic reticulum, ribosomes
44
what are the stages in the cell cycle?
```
G1= growth
S= DNA synthesis
G2= growth/ prepare for mitosis
M= mitosis
```
45
what stages make up interphase?
G1, S, G2
46
what happens in interphase?
organelles double, the cell grows, DNA replicates
47
what is the equation for mitotic index?
number of cells with visible chromosomes/ total number of cells observed
48
what happens in mitosis?
prophase=
chromosomes condense and become visible, centrioles separate and move to opposite poles of the cell, spindle fibres are formed
metaphase=
chromosomes align along the equator, spindle fibres release and attach to the centromere and chromatid
anaphase= spindle fibres pull the centromere and chromatids to opposite poles, requires ATP
telophase= chromosomes are long and thin, spindle fibres disintegrate, nucleus reforms
49
what are cancers/ tumours?
result of mutations in genes regulating mitosis, uncontrolled cell growth
50
what is a benign tumour?
large, slow growth, non- cancerous
51
what is a malignant tumour?
large and rapid growth, can break off and spread
52
what is the job of radiotherapy?
to damage DNA so that a cell dies
53
what is the job of chemotherapy?
prevents DNA replication to slow mitosis
54
what is the head of the phospholipid bilayer?
hydrophilic
55
what is the tail of the phospholipid bilayer?
hydrophobic
56
what is the job of cholesterol?
to restrict the movement of molecules in the membrane, less fluid at high temperatures, prevents water and ions from leaking out of the cell
57
what is the job of proteins in the phospholipid bilayer?
structural support, channel to transport substances, form receptors
58
why is the cell membrane described as 'fluid mosaic'?
phospholipids can move and proteins are embedded throughout
59
what is simple diffusion?
the net movement of molecules from high to low concentration until equilibrium is reached
60
what is facilitated diffusion?
where proteins are used to transport molecules from high to low concentration
61
what is the job of a carrier protein?
bind with a large molecule that changes the shape of the protein, so that the molecule is released on the other side of the membrane
62
what is the job of a channel protein?
form pores for charged particles to pass through
63
what is osmosis?
the movement of water from an area of high water potential to an area of low water potential across a partially permeable membrane
64
what is water potential?
the pressure created by water molecules
65
what is water potential measured in?
kPa
66
what is the water potential of pure water?
0kPa
67
what happens when solutes are added to pure water?
becomes more negative
68
what is an isotonic solution?
water potential on both sides of the membranes are the same
69
what is a hypotonic solution?
water potential of a solution is more positive than the cell, water moves into the cell so it becomes turgid
70
what is a hypertonic solution?
water potential of a solution more negative than the cell, so water moves out and the cell becomes shrivelled
71
what is active transport?
movement of molecules from an area of low concentration to high concentration using ATP and carrier proteins
72
what happens when ATP is binded to the carrier protein?
it is hydrolysed into ADP and Pi
73
what happens when the molecule changes shape?
it is released on the other side of the membrane
74
what is a lymphocyte?
type of immune cell, that distinguishes between pathogens and the body's own cells
75
what are pathogens?
non self cells
76
what is the specific immune response?
slower and specific, cell mediated/humoral response
77
what is the non specific human response?
immediate and the same for all pathogens
78
what is an antigen?
protein that generates an immune response
79
what is antigen variability?
when the pathogen's DNA mutates frequently, so the shape of the antigen changes
80
what is the result of antigen variability?
previous immunity is no longer effective
81
what is a macrophage?
a type of white blood cell that carries out phagocytosis
82
what are the stages of phagocytosis?
1) chemicals from pathogens attract phagocytes
2) receptors on phagocytes attach to pathogens
3) phagocyte changes shape to engulf pathogens
4) contained in a phagocytic vesicle
5) lysosome fuses with a phagosome, releases lysozyme enzymes
6) hydrolyses the pathogen
7) pathogen is destroyed
83
what are T lymphocytes involved in?
the specific immune response
84
where are T lymphocytes made?
made in the bone marrow and matures in the thymus
85
what is an antigen presenting cell?
cell presenting a non self antigen on their surface
86
what is the process of cell mediated immunity?
1) pathogen engulfed and destroyed by a phagocyte and becomes an antigen presenting cell
2) helper T cells have receptors that attach to antigens on the antigen presenting cell
3) activates T cells to divide by mitosis to make clones
4) cloned T helper cells differentiate
87
what are the results of when T helper cells differentiate?
activates B lymphocytes, stimulates macrophages, becomes memory cells, become cytotoxic T cells
88
where are B lymphocytes made?
made and mature in the bone marrow
89
what are the stages of humoral immunity?
1) antigens collide with their complementary antibody on a B cell
2) B cell takes in an antigen by endocytosis and presents on the cell membrane
3) B cell collides with helper a T cell receptor
4) activates a B cell to go through clonal expansion and clonal selection (differentiation)
5) B cells undergo mitosis
6) differentiate into plasma/memory cells
7) plasma cells make antibodies, B cells rapidly divides into plasma cells when re infected to make large numbers rapidly
90
what is the primary immune response?
the first time the pathogen infects, slower immune response, immune system needs time to adjust
91
what is the structure of an antibody?
quaternary structure, 4 polypeptide chains, variable region, constant region, heavy/light chain, disulphide bridge
92
what is the function of the variable region?
changes shape to be complementary to antigen
93
what is the function of the disulphide bridge?
stabilises the tertiary structure
94
what is agglutination?
when antibodies that are flexible and bind to multiple antigens they clump together, makes it easier for phagocytes to locate and destroy pathogen
95
what are monoclonal antibodies?
produced from genetically identical B cells
96
what is direct monoclonal antibody therapy?
specific antibody binds to the antigen on cancer cells
antibody binding blocks chemical signals
which reduces tumour development
97
what is indirect monoclonal antibody therapy?
radioactive/cytotoxic drug attached to the monoclonal antibody
antibody binds to the antigen on cancer cells
which brings the drug to the tumour site
this results in cancer cell death
98
what does ELISA stand for?
enzyme linked immunosorbent assay
99
how does an ELISA test work?
1) antigen from patient sample bound inside the well plate
2) detection antibody has an enzyme attached complementary to the antigen of interest
3) if the antigen is present, a detection antibody binds
4) well is rinsed, substrate solution added, if an antigen is present the enzyme reacts which results in colour change
100
what hormone is produced in placenta?
produces hCG
101
what does an pregnancy test contain?
specific antibodies for hCG to bind to coloured beads
102
what sample is needed for an pregnancy test?
urine
103
what does the test region contain on a pregnancy test?
immobilised antibodies for hCG
104
what is the reasoning behind herd immunity?
if enough people are vaccinated, it won't easily spread
105
what does a vaccination contain?
small amounts of the weakened or dead pathogen
106
what is passive immunity?
antibodies are introduced into the body, pathogen doesn't enter so no plasma/memory cells, no long term immunity
107
what is active immunity?
immunity from pathogen exposure- natural or artificial
108
how do vaccinations work?
exposure to antigen activates B cell to undergo clonal expansion and selection
B cells undergo mitosis to make cells
differentiate into plasma/memory cells
plasma cells make antibodies
B memory cells rapidly divide into plasma cells
109
what do memory B cells divide into after mitosis?
plasma cells
110
what is the core of HIV made from?
genetic material (RNA) and reverse transcriptase
111
what is the capsid of HIV?
outer protein coat
112
what is the envelope of HIV made from?
the host cell's membrane
113
where is HIV transported?
in the blood
114
what are the stages of HIV replication?
HIV transported in the blood until it attaches to a CD4 protein on the helper T cells
HIV protein capsule fuses with the helper T cell membrane
RNA and enzymes from HIV enter
HIV enzyme reverse transcriptase copies viral RNA into a DNA copy
moves to the helper T cell nucleus
mRNA is transcribed
helper T cells create viral proteins to make new viral particles
115
what does HIV positive mean?
a person is infected with HIV
116
what is AIDS?
replicating viruses in helper T cells that interfere with normal functioning of the immune system
