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cell recognision Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

how do cells tell the difference between self and non self cells

A

they have different antigens which the body wont recognise which triggers an immune response so will therefore attack it.

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2
Q

what do antigens allow the body to identify

A

pathogens, abnormal body cells, toxins, cells from other organisms of the same species

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3
Q

what is phagocytosis

A

the cellular process of engulfing solid particles using the cell membrane carried out.

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4
Q

steps of phagocytosis

A
  1. pathogen recognises the foreign antigens. travels towards the pathogen by chemotaxis. pathogen attaches to the phagocyte by receptors.
  2. the pathogen binds to receptors on the phagocyte cell membrane and is engulfed by the phagocyte and forming a phagosome
  3. lysosomes fuse to phagosomes to form phagolysosomes and release a digestive enzyme to digest the pathogen.
  4. harmless products are removed by exocytosis or used by the phagocyte and presents antigens on cell surface membrane
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5
Q

what do antigen presenting cells activate

A

they activate t helper cells which stimulates and recruits more phagocytes and t cells to carry out an immune response

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6
Q

types of t cells

A

t helper cells which activate b cells and immune responses and cytotoxic t cells which destroy foreign cells by releasing chemicals such as perforin

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7
Q

two parts to a specific immune response

A

cell mediated response- specialised white blood cells (T lymphocytes) which target pathogens outside and inside cells.
humoral response- specialised white blood cells (B lymphocytes) which target pathogens by producing antibodies.

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8
Q

cell mediated immune response

A

APCs can be either phagocytes or cells that have been invaded by the pathogen. T cells respond to the cells which is presenting the antigen. T helper cells respond first as the have receptors that fit exactly to the presented antigen. activates the T cells and begin to differentiate and recruit other T cells and activate B cells.

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9
Q

how do B cells help in immune responses

A

B cells get the antigen from antigen from pathogens or APCs and presents antigens in its cell surface membrane. T helper cells bind to the antigen to activate the B cells. the b cells begin to divide by mitosis to form plasma cells and memory cells that is known as clonal selection. plasma cells produce antibodies that are complimentary to the antigens.

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10
Q

how does the body prepare for secondary responses

A

the body has memory cells with stay in the blood stream. if they come into contact with the antigen again the response fast.

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11
Q

differences between primary and secondary responses

A

in primary responses there aren’t many b cells to make antibodies and they only survive for a few days. in secondary responses they produce antibodies much more quickly and more new memory cells.

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12
Q

structure of antibodies

A

they are proteins made out of four polypeptide chains, 2 heavy and 2 light chains.

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13
Q

do all antibodies have the same constant region

A

yes

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14
Q

what does the constant region allow

A

it allows them to bind to receptors on immune system cells.

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15
Q

what are the 2 variable regions

A

the antigen binding sites so they will have a unique tertiary structure complementary to an antigen.

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16
Q

what is agglutination

A

antibodies bind to antigens on pathogens causing them to clump together. clumps are destroyed by phagocytosis. easier for phagocytes to engulf more pathogens.

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17
Q

neutralising toxins

A

some antibodies work well by neutralising toxins released my pathogens.

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18
Q

how do antibodies prevent viruses from entering the host cells

A

viruses have spike proteins on their surface which recognise and bind to receptors on the surface of the host cell which allows them entry into the cell. antibodies bind to these viruses and stop them attaching to their host cells.

19
Q

what is antigenic variation

A

when pathogens can form different strains which often have different antigens.

20
Q

what does antigenic variation allow

A

means that when people have a secondary infection the memory cells will not remember the antigen so no antibodies, so a primary response will happen again.

21
Q

what do monoclonal antibodies help with medically

A

pregnancy tests, radioimmunology, ELISA tests

22
Q

radioimmunology

A

allows doctors to target radiation to specific sites. links radioactive atoms to monoclonal antibodies that deliver the radioactivity by latching onto proteins found in cancer cells. they use it to find tumours.

23
Q

pregnancy tests

A

antibodies complimentary to hCG protein are bound to coloured beads. the protein in the urine binds to antibodies. urine moves up the strip carrying the bead of colour. binds to the first line ‘the blue line’.

24
Q

ELISA test

A

antigen is attached to a well in a test dish. sample of blood plasma is added to the well. if antibodies are present, bind to the antigen. the well is washed. secondary antibody with an enzyme attached is added. binds to the antibody. well is washed again. changes colour is enzyme is present.

25
Q

what are vaccines

A

there are dead or inactive pathogens that are put in to the body so it stimulates the production of antibodies and memory cells.

26
Q

how can pathogens be prepared for a vaccine

A

by killing the antigen, weakening the antigen, purifying the antigen, and using inactivated toxins

27
Q

ethical issues with vaccines

A

animal testing. human trials put themself at risk, people may reject vaccines due to side effects, difficult to decide who is first to have the vaccines.

28
Q

why don’t vaccines fully eliminate the disease

A

as it may fail to induce immunity in some people. antigenic variability as pathogens can mutate. there are many strains so can be vaccinated against all. not everyone wants to have the vaccine due to religious or ethical grounds.

29
Q

what is herd immunity

A

herd immunity is where most of the population are vaccinated so it protects the people who don’t get the vaccine due to it being above a threshold.

30
Q

what is active immunity

A

where the body makes antibodies after being exposed to the antigens. long term protection due to memory cells

31
Q

what is natural active immunity

A

becoming immune after catching the disease

32
Q

what is artificial active immunity

A

becoming immune after getting a vaccination of a dead or inactive form of the pathogen

33
Q

what is passive immunity

A

the body is given the antibodies that have been made by different organisms

34
Q

what is natural passive immunity

A

a baby gets antibodies through the placenta and in breast milk.

35
Q

what is artificial passive immunity

A

injected with antibodies for example if you get tetanus, you get injected with antibodies against tetanus toxins

36
Q

problems with passive immunity

A

maternal antibodies pass from the placenta into the foetal blood. protection is only temporary so only lasts a few months after birth.

37
Q

the structure of HIV

A

membrane envelope- the outer layer. capsid- protects genetic information. RNA or can be DNA. glycoproteins- antigens. reverse transcriptase enzyme- turns RNA into DNA

38
Q

how does HIV work

A

it works by infection T helper cells. the virus replicates in the T helper cells which causes the cell to burst. the number of T cells decrease, and eventually leads to AIDS

39
Q

how does HIV replicate

A

glycoproteins on the virus bind to CD4 receptors on the T helper cells. allows the envelope surrounding the virus to fuse with the T helper membranes. the capsid released into the cell where it releases the RNA and reverse transcriptase. reverse transcriptase is used to make DNA from the HIV RNA template. DNA is inserted into the cells DNA which is replicated. DNA used to make HIV RNA and proteins at the host ribosomes. virus particles assemble which bud off and go on to infect other cells.

40
Q

how is HIV transmitted

A

having unprotected sex, close contact with infected blood, mothers infected milk on to child, infected blood transfusion.

41
Q

what is AIDS

A

AIDS occur when T helper cells reach a critical levels. the immune system can not fight off infections that the body would usually fight off. eventually fatal.

42
Q

symptoms of AIDS

A

the symptoms tend to be lots of minor infections due to the critical levels of T helper cells.

43
Q

treatment of AIDS

A

antiretroviral drugs are now available which can reduce levels so much it can be undetectable. however there is no cure for HIV.

Biology (12 decks)

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