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biology > 2-C immunity > Flashcards

2-C immunity Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

what is an antigen?

A

a molecule that generates an immune response

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2
Q

what is an pathogen?

A

disease causing microorganism

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3
Q

what is an antigen presenting cell?

A

a cell with a pathogens antigens on the cell membrane

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4
Q

what is a phagocyte?

A

a type of white blood cell that carries out phagocytosis

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5
Q

what is phagocytosis?

A

the engulfment of pathogens

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6
Q

what is the first stage of phagocytosis?

A

phagocyte recognises the foreign antigen on a pathogen

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7
Q

what is the second stage of phagocytosis?

A

cytoplasm of phagocyte moves round pathogen engulfing it

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8
Q

what is the third stage of phagocytosis?

A

pathogen is contained in phagocytosis vacuole

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9
Q

what is the fourth stage of phagocytosis?

A

lysosome fuses with phagocytic vacuole and releases lysozyme which break down pathogen

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10
Q

whatvis the fifth stage of phagocytosis?

A

phagocyte presents pathogens antigens on cell membrane which activates other immune system cells

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11
Q

what is part A of the cell mediated response?

A

Helper T cell with complementary receptor to antigen presenting phagocyte is drawn to area
binds to APC and releases a chemical (interleukin) which attracts more phagocytes to the area

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12
Q

what is a T helper cell?

A

cells that act as a coordinator of the immune response

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13
Q

what is part B of the cell mediated response?

A

T helper cell with a complementary receptor to antigens on infected body cell and binds releasing a chemical to attract cytotoxic T cells
Tc cells destroy infected cells

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14
Q

what is the first stage of the humoral response?

A

clonal selection - B cell with complementary receptor to antigen binds to antigens on pathogen/antigen presenting cell
T Helper activated B cell to divide my mitosis

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15
Q

what is the second stage of the humoral response?

A

clonal expansion - clones of B cell become plasma or memory cells

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16
Q

what are plasma cells?

A

releases monoclonal antibodies specific to foreign antigen in large quantities
short lived

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17
Q

what are memory cells?

A

long lived
bring about secondary immune response
give long term immunity

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18
Q

what is the structure of antibodies?

A

globular protein - made of 4 polypeptides in quarternary structure
have two binding sites (variable region) which are specific to antigens due to different tertiary structure
have constant regions

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19
Q

what is agglutination?

A

antibodies have two binding sites so can bind to two pathogens so they become clumped together
allows phagocytes to more than one pathogen and destroy them quicker

20
Q

what is the primary response?

A

the immune response that is triggered when a foreign antigen enters the body for the first time
slow response due to few B cells so infected person will show symptoms

21
Q

what is the secondary response?

A

immune response triggered when the foreign antigen enters the body for the second time
quicker response as clonal selection happens faster
pathogen is often destroyed before symptoms can show

22
Q

what is a active immunity?

A

when your immune system makes it’s own antibodies after being stimulated by an antigen
takes awhile for protection to develop
memory cells are produced
protection is long term

23
Q

what is passive immunity?

A

when you get immunity from being given antibodies from a different organism
protection is immediate
memory cells aren’t produced
protection is short term

24
Q

what is natural active immunity?

A

when you become immune after catching a disease

25
Q

what is artificial active immunity?

A

when you become immune after you’ve had a vaccination containing a harmless dose of antigen

26
Q

what is natural passive immunity?

A

when a baby becomes immune due to receiving antibodies from its mother (eg from placenta or breast milk)

27
Q

what is artificial passive immunity?

A

when you become immune after being injected with antibodies from someone else (eg tetanus shot)

28
Q

what are vaccinations?

A

contain antigens that cause your body to produce memory cells against a particular pathogen so you can get immunity without producing symtpons
the antigens may be free or attached to a dead/attenuated pathogen

29
Q

what is herd immunity?

A

where unvaccinated people are protected because the disease is reduced by vaccinated people

30
Q

what are ethical issues of vaccines?

A

tested on animals before humans
testing on humans can be risky - eg volunteer vaccinated with HIV may have unprotected sex and vaccine might not work
side effects
if there was an epidemic it is difficult to decide who is vaccinated first

31
Q

what is antigenic variation?

A

some pathogens can change their surface antigens meaning the memory cells won’t work
immunity response has to start from scratch
makes it difficult to develop vaccines

32
Q

what are monoclonal antibodies?

A

antibodies produced from a single group of genetically identical B cells (plasma cells)
monoclonal antibodies can be made to bind to anything

33
Q

how are monoclonal antibodies used in anti cancer drugs?

A

cancer cells have antigens (tumour marker) that are not found in normal body cells
MA can be made to bind to them
when the antibody comes in contact with the tumour marker for he drug will accumulate so have fewer side effects as they are localised

34
Q

how are monoclonal antibodies used in pregnancy tests?

A

pregnancy tests detect hCG in the urine of pregnant women
test contains antibodies bound to blue bead
complementary to hCG
when urine is applied hCG will bind to the antibodies forming antigen-antibody complex
urine moves up strip carrying beads
if hCG is present strip turns blue

35
Q

what is the ELISA test?

A

enzyme linked immunoabsorbent assay that shows if patient has antibodies/antigens (shown by colour change)
can be linked in medical diagnosis to test for pathogenic infection/allergy

36
Q

what is a direct ELISA test?

A
  • uses single antibody complementary to antigen being tested
  • antigens from patient sample are bound inside a well plate
  • a detected antibody complementary to antigen is added
  • if antigen of interest is present it will be immobilised on the surface of the well and detection antibody will bind
  • well is washed out removing unbound antibodies and a substrate is added
  • if the detection antibody is present the enzyme reacts with substrate changing the colour
37
Q

what is an indirect ELISA test?

A

used two different antigens and can be used to test for HIV
-HIV antigen is bound the the well plate
-sample of patients blood plasma is added (if there are HIV antibodies they will bind to antigens)
-well is washed out and secondary antibody (with enzyme) is added and can bind to primary antibody
-well is washed out to remove unbound secondary antibodies
—>if there are no primary antibodies secondary antibodies will be all washed out
-solution contains substrate is added which can bing to enzyme producing a coloured protein

38
Q

what is HIV?

A

human immunodeficiency virus that affects the immune system of humans
leads to AIDS
infects and kills helper T cells (host cell) which are important chemical signallers in the immune system so wi tho our then cause the immune system vulnerable to infections

39
Q

what is AIDS?

A

acquired immune deficiency syndrome causes the immune system to deteriorate and fails
makes the sufferer more vulnerable to infections

40
Q

what is the initial infection and latency period?

A

initial infection period-HIV replicates rapidly and the infected person my experience flu like symptoms
latency period-HIV replication rage drops (can last years) and no symptoms

41
Q

what are the symptoms of AIDS?

A

initially:
minor infections or mucous membranes
recurring respiratory infections
middle:
more susceptible to serious infections like diarrhoea bacterial infections and tuberculosis
late stages:
serious infections like toxoplasmosis (brain parasite) candidiasis (respiratory fungal infection)
length of survival varies depending on age and healthcare recieved

42
Q

what is the structure of HIV?

A

spherical structure
made up if a core contains genetic material (RNA and proteins eg reverse transcriptase)
outer protein coating called capsule and envelope layer surrounding it
attachment proteins attached to envelope to attach to host cell

43
Q

what is HIV replication?

A
  1. attachment protein attached to receptor molecule on cell membrane of host helper T cell
  2. capsid releases into cell and is uncontested releasing genetic material into cytoplasm
  3. reverse transcriptase makes complementary strand of DNA
  4. double DNA strand is made and inserted into human DNA
  5. host cell enzymes make viral proteins from DNA
  6. viral proteins are assembled which bud from cell and infect other cells
44
Q

why don’t antibiotics work on viruses?

A

antibiotics kills bacteria by targeting their enzymes and ribosomes
viruses don’t have their own enzymes and ribosomes (use host cell) so antibiotics can’t inhibit them without targeting human cells

45
Q

how is HIV infection controlled?

A

by reducing spread
can be spread via unprotected sex and infected bodily fluids (sharing needles)
babies can be infected from mother but antiviral drugs during pregnancy can reduce this chance

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