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A-level Biology > Chapter 5 - Cell recognition and cell membranes > Flashcards

Chapter 5 - Cell recognition and cell membranes Flashcards

1
Q

what is an infection

A

an interaction between the pathogen and the defence mechanisms of the body

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2
Q

what is an antigen

A

a protein found on the cell surface of pathogens that generate an immune response

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3
Q

what is a pathogen

A

a disease causing microorganism

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4
Q

what is immunity

A

when the body is well equipped against invasion from a pathogen so it doesn’t harm the individual

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5
Q

what must lymphocytes do before attacking an invader

A

distinguish between cells that belong to the individual and cells that don’t

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6
Q

what are the four things that the immune system can identify

A

pathogens non self material toxins and abnormal body cells

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7
Q

why can the immune system be a problem when receiving organ donations

A

the antigens are recognised as non self so without immunosuppressants the immune system would try and attack it

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8
Q

what is a non specific response

A

the response is immediate and the same for all pathogens

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9
Q

what is a specific response

A

the response is slower and specific to each pathogen

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10
Q

two types of non specific response

A

physical barriers and phagocytosis

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11
Q

two types of specific response

A

cell mediated response and humeral response

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12
Q

how many types of lymphocyte are there

A

10 million

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13
Q

how do lymphocytes recognise cells belonging to the body

A

in the womb lymphocytes are constantly colliding with the body cells of the feuds.
some lymphocytes will have sites that are complementary to these cells
these will either die or be suppressed
the remixing lymphocytes are those that are complementary to non self material that the fetus hasn’t yet been exposed to
in adults the same process happens in bone marrow producing only lymphocytes that will be able to fight an infection

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14
Q

what are the two types of white blood cell

A

phagocyte and lymphocyte

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15
Q

process of phagocytosis

A

a phagocyte recognises foreign antigens on the pathogen
receptors on the phagocyte bind to the pathogen
they engulf the pathogen forming a phagosome
lysosomes fuse with the phagosome
lysosomes hydrolyse the cell walls of the bacteria breaking it down
the phagocyte presents the antigens of the pathogen on its surface

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16
Q

what are the two types of lymphocyte

A

b lymphocyte

t lymphocyte

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17
Q

where do b lymphocytes mature

A

bone marrow

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18
Q

where do t lymphocytes mature

A

thymus gland

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19
Q

what type of immunity are B cells associated with

A

humoral

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20
Q

what type of immunity are T cells associated with

A

cell mediated

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21
Q

what are antigen presenting cells

A

cells that can present foreign antigens on their surface

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22
Q

how do T cells recognise cells to destroy

A

they display foreign antigens

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23
Q

how do T cells help to destroy pathogens

A

receptors on the t helper cells are complementary to the antigens presented on the surface of phagocytes. this attachment stimulates the T cell to divide rapidly by mitosis forming cloned cells these cells can do one of four things

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24
Q

what are the four things that can happen to T cells after they have been cloned

A

a memory cells
b stimulate phagocytes for phagocytosis
c stimulate B cells
d activate cytotoxic T cells

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25
how do cytotoxic T cells kill cells
they produce a protein called perforin which creates holes in the cell surface membrane so the cell loses control of what enters and leaves and the cell dies
26
what is humeral response
response to infection using antibodies
27
what is clonal selection
each B cell has a differently shaped actively site which is complementary to online antigen. when the body is infected with the pathogen with this antigen the B cell engulfs it and displays the antigen. the cell bind to this displayed and stimulate B cell to divide by mitosis
28
what is the name of the process by which B cells display a foreign antigen on their cell surface
endocytosis §
29
when B cells are cloned what are the two things they can turn into
memory cells or plasma cells
30
what type of cell is responsible for the primary defence
plasma cell
31
what do plasma cells do
they bind to the antigen to form an antibody antigen complex
32
how do plasma cells kill pathogens
antibodies have two binding sites meaning they can bind to multiple pathogens at once. this causes them to clump together agglutination so phagocytes recognise and destroy them
33
how do memory cells help to kill pathogens
they coordinate the secondary response when you are infected again they divide rapidly to produce plasma cells which secrete antibodies and more memory cells so there is less chance of becoming ill
34
why is the primary immune repose so slow
there aren't many B cells that can secrete the antibody needed to fight pathogen
35
what happens during the primary immune repose
you show signs of the disease it takes time for the necessary B cells to be made. then memory cells are made which make the secondary response faster
36
why do you often show no symptoms of a disease after being infected a second time
clonal selection happens faster so the right B cells and antibodies are created quicker and the immune system gets rid of any pathogens before you show symptoms
37
how many polypeptide chains are antibodies made form
4 two heavy and two light
38
what is the binding site on each antibody called and why
the variable region it differs between all antibodies so they are specific to just one antigen
39
what are the two ways in which antibodies can help to destroy cells
agglutination - clumping that pathogens together | they act as markers which stimulate the phagocytes to attack the pathogen
40
what are monoclonal antibodies
antibodies produced from a single group of genetically identical B cells
41
why do antibodies have unique binding sites
they have unique tertiary structures
42
what are the two ways in which monoclonal antibodies can help cure cancer
1) antibodies with a complementary shape to the tumour markers on the cancer cells are produced. they attach to the cells and block the chemical signals that stimulate tumour growth 2) anti cancer drugs are attached to the antibodies when they bind to the antigens on the tumour they release these chemicals which destroy the cells
43
how are monoclonal antibodies used to diagnose certain cancers
with some cancers a higher level of a certain protein will be present. monoclonal antibodies that interact with this protein are given to the person and highlight the increased levels
44
how are monoclonal antibodies used in pregnancy test kits
mothers produce hCG when they are pregnant the application area of the stick contains antibodies for hCG which are attached to a blue dye if hCG is present it will bind with the antibodies forming a complex and move up the strip and carry the blue dye with it. at the test strip there are immobilised antibodies. any hCG will bind with these antibodies and the blue dye will show up in a solid line
45
3 ethical concerns with monoclonal antibodies
making mice produce tumour cells involved deliberately giving the cancer there have been deaths associated with monoclonal antibodies treating MS in one experiment six healthy volunteers suffered organ failure
46
how are monoclonal antibodies produced
a mouse is exposed to the disease the B cells in the mouse make antibodies which are extracted these cells are mixed with tumour cells detergent breaks down the cell membranes so the two can fuse together forming a hybridoma the hybridoma cells are separated and cloned successful clones are produced on a large scale
47
what is passive immunity
the type of immunity you get form being given antibodies by a different organism
48
why is passive immunity only temporary
no memory cells are formed
49
what is active immunity
the body is stimulate by an antigen into producing its own antibodies
50
what is natural active immunity
an individual is infected with a disease under normal circumstances
51
what is artificial active immunity
inducing an immune repose in an individual without them getting the disease
52
which type of immunity means you have to be exposed to an antigen
active
53
which type of immunity gives you immediate protection
passive
54
which type of immunity produced memory cells
active
55
which type of immunity is long lasting
the antibody as well as memory cells are produced by the body after infection
56
4 features of successful vaccination programme
the vaccine must be cheap and widely available minimum side effects must be possible to achieve herd immunity there must be appropriate means of administering it
57
why are vaccines so good
they allow you to build up memory cells to a disease without suffering from it
58
why are booster vaccines given
to make sure that sufficient memory cells are produced
59
why are vaccines not given orally 2
it may be broken down by enzymes in the gut | it could be too large to be absorbed into the blood
60
what is herd immunity
when such a large proportion of the population has been vaccinated against a pathogen it makes it difficult to spread
61
why is herd immunity important
it is never possible to vaccinate all people in a population against a disease
62
why might vaccination be ineffective 4
antigenic variability certain pathogens can 'hide' from the vaccine there may be too many strains of a pathogen to vaccinate against all of them people with defective immune systems won't be effective
63
what is antigenic variation
some pathogens can change the antigens on their surface so the antibodies in our bodies aren't effective against them anymore memory cells of our previous vaccination won't recognise these antigens as foreign so we will be infected again
64
ethical issues with vaccines 4
animal testing testing on volunteers can lead to unnecessary illness its unfair that those who don't want the vaccine due to the side effects are protected by herd immunity in an epidemic difficult decisions about who would receive the vaccine
65
which disease was the MMR vaccine linked to
autism
66
what is an antibody
a protein produced by a B cell in reposes to the complementary antigen
67
what are cytokines
chemicals secreted by t helper cells to activate B cells
68
ethical issues with monoclonal antibodies
animals are purposefully given cancer to produce the tumour cells needed
69
flaws with the research suggesting MMR vaccine leads to autism
the sample size was just 12 children | the bias of medical companies conducting it
70
what can HIV lead to
AIDS
71
what is AIDS
the immune system weakens and eventually fails so the victim is more susceptible to infections
72
how does HIV caused symptoms of AIDS
it infects and eventually kills the t helper cells these cells are what stimulate phagocytes, cytotoxic T cells and B cells. without T cells the body can't fight infection and so you become very ill
73
when do people with HIV develop AIDS
when the helper T cells in their body reach critical low levels
74
what is enclosed in the capsid of an HIV cell
the genetic material RNA and enzymes reverse transcriptase
75
what is the capsid made from
protein
76
what does reverse transcriptase do
it turns the RNA in the viral cell into DNA in the host cell
77
how does HIV replicate
hiv enters the body and circulates around the bloodstream the attachment proteins bind to CD4 proteins found on the surface of helper T cells the capsid fuses with the cell surface membrane releasing the genetic material and enzyme into the cell once there reverse transcriptase converts the virus' RNA into dna. the dna moves into the nucleus of the t helper cell. once there the dna makes mRNA using the cells enzymes this contains instructutuins for making new viral proteins and RNA. the mRNA leaves through the nucleus pore and uses the cell protein synthesis mechanisms to make HIV particles. a piece of t helper cells cell membrane surrounds the particles and they break away forming new viruses
78
what are the initial symptoms of AIDS
infections of mucous membranes eg nose ears and genitals
79
factors that affect the progression of HIV to AIDS
existing infections strain of HIV access to healthcare
80
what happens during the late stages of HIV
the patients can develop a variety of serious infections like fungal infections of the respiratory system which ultimately kill the patient
81
what drugs are given to slow down the progression of hiv
antiviral drugs
82
how can hiv be spread from person to person 3
unprotected sex infected bodily fluids from mother foetus
83
how do antibiotics kill bacteria
bacteria cells are surrounded by a cell wall made of a protein called murein as water enters the cell by osmosis the cells stretches against the wall. the murein is inelastic and so stops more water form moving into the cell antibiotics stop the production of murein which weakens the cell walls. when water moves into cells with these weak walls they burst
84
why don't antibiotics kill viruses
they have no cell wall made of murein that the antibiotic could destroy
85
what does the ELISA test do
uses antibodies and antigens to see if a patient has a surprising number of antigens or antibodies
86
how does the ELISA test work
apply the sample to a surface wash to remove any unattached antigens add the antibody that is specific to the antigen leave the two to bind together wash the surface again to remove any excess antibodies add a secondary antibody attached to an enzyme which can bind with the first antibody add the colourless substrate of the enzyme the enzyme will act upon the substrate to turn it coloured the amount of the antigen present is relative to the intensity of the end colour observed
87
how are antibodies produced
1 virus contains antigen 2 virus engulfed by phagocyte / macrophage 3 presents antigen to B cell 4 memory cells/ B cells become activated 5 divides to form clones 6 by mitosis 7 plasma cells produce antibodies 8 antibodies specific to antigen 9 correct reference to T cells - cytokines
88
what are cytokines
chemicals produced by T cells which stimulate B cells to divide by mitosis
89
describe how the presentation of a virus antigen leads to the secretion of an antibody against this virus antigen
1 helper T cell/TH cell binds to the antigen 2 this helper T/TH cell stimulates a specific B cell 3 B cell clones/divides by mitosis 4 forms plasma cells that release antibodies

A-level Biology (19 decks)

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