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bio > 3.2 Cells immunity > Flashcards

3.2 Cells immunity Flashcards

1
Q

define antigen

A
  • recognised as nonself/foreign by immune system

- will stimulate immune response +production of antibodies

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2
Q

antigens are specific so immune system can identigy

A
  • pathogens
  • cells from other organisms of same species
  • abnormal body cells
  • toxins released from bacteria
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3
Q

describe phagocytosis

A
  1. phagocyte recognises foreign antigens on pathogen + binds to antigen, is attracted to pathogen by chemotaxis
  2. phagocyte engulfs pathogen surrounding it with its cell surface membrane
  3. pathogen contained in vacuole of cytoplasm of phagocyte
  4. lysosyme fyses with phagosome + releases hydrolytic enzymes into phagosome
  5. these hydrolyse pathogen
  6. phagocyte becomes antigen presenting cell + stimulates immune response
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4
Q

describe the cellular response

A
  1. T lymphoyctes recognise antigen presenting cells after phagocytosis
  2. specific T helper cells with receptor complementary to specific antigen binds to it, becoming activated + dividing by mitosis to form clones whicb
    - stimulate B cells for humoral response
    - stimulate cytotoxic T cells to kill infected cells by producing perforin
    - stimulate phagocytes to engulf pathogens by phagoctyosis
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5
Q

describe the humoral response

A
  1. clonal selection
    - specific B cells bind to antigen presenting cells +stimulated by T h cells
    - divides rapidly by mitosis undergoing clonal selection
  2. some become B plasma cells - secrete monoclonal antibodies
  3. some becom B memory cells - for secondary immune response
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6
Q

what is the primary response

A
  • antibodies produced slower + low conc
  • not many B cells to make antibodies
  • Th cells need to activate B plasma cells
  • symptoms shown
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7
Q

what is the secondary response

A
  • produces antibodies faster + higher conc
  • B + T memory cells present
  • B memory cells undergo mitosis quicker/ quicker clonal selection
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8
Q

what are antibodies

A
  • quaternary structure protein
  • secreted by B cells
  • binds to specific antigens
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9
Q

describe + explain how structure of antibody is related to its function

A

primary structure - sequence of amino acids in polypeptide chain
- determines folds in secondary structure
- determines specfic shape of tertiary structure + position of bonds
quaternary structure - 4 polypeptide chains
- enables specific shaped variable region

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10
Q

how do antibodies work to destroy pathogens

A

binds to two pathogens at the same time
enables antibodies to clump pathogens together - agglutination
phagocytes bind to antibodies + phagocytose many pathogens at once

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11
Q

what is vaccination

A
  • injected antigens
  • from attenuated pathogens
  • stimulates formation of memory cells
  • vaccine can lead to symptoms
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12
Q

how does the use of vaccines provide protection of individuals against disease

A
  • normal response, memory cells produced
  • on reinfection, antibodies produced faster + higher conc
  • destruction of pathogen before any harm
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13
Q

how does the use of vaccines provide protection of populations against disease

A
  • herd immunity
  • makes it more difficult for pathogen to spread through population
  • more people immune for fewer people carry disease
  • fewer susceptible so less likely non vaccinated individual will come into contact with infected person + pass on disease
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14
Q

what is active immunity

A
  • initial exposure to antigen
  • memory cells involved
  • antibody produced secreted by B plasma cells
  • slow
  • long term
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15
Q

what is passive immunity

A
  • no exposure to antigen
  • no memory cells involved
  • antibody introduced into body i.e breast milk
  • fast
  • short term, antibody broken down
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16
Q

ethical issues of vaccines

A
  • tested on animals, can feel pain
  • tested on humans , unnecessary risk
  • side effects
  • expensive
17
Q

effect of antigen variability on disease

A
  • change in antigen shape due to genetic mutation
  • not recognised by B memory cells = no antibodies
  • not imune
  • reungerdo primary response - slow release/ low conc of antibodies
  • symptoms of disease
18
Q

effect of antigen variability on disease prevention

A
  • change in anitgen shape due to genetic mutation
  • exisiting antibodies unable to bind to changed antigens
  • immune system wont recognise different antigens
19
Q

what is a successful vaccination programme

A 
produce suitable vaccine
-effective - make memory cell
-no major side effects 
-low cost
-easily produced/transported/stored/administered 
provides herd immunity
20
Q

use of monoclonal antibodies

A

monoclonal antibody - antibody produced from single group of genetically identical B cells
bind to specific complementary antigen
- have a binding site/variable region with a specific tertiary structure
- only one complementary antigen will fit

21
Q

replication of HIV in T h cells

A
  1. HIV infects T h cells
    - HIV attachment protein attaches to receptor on T h cell membrane
  2. Virus lipid envelope fuses with cell surface membrane + capsid released into cell, releasing RNA + reverse transcriptase
  3. Viral DNA made from viral RNA
    - reverse transcriptase produces complementary viral DNA strand from viral RNA template
    - double stranded DNA made
  4. viral DNA into host DNA
  5. host cell enzymes used to make viral proteins from viral DNA
  6. viral proteins assembled with viral RNA to make a new virus
  7. new virus buds from cell, taking some cell surface membrane as envelope
  8. kills T h cells
  9. most host cells infected + process repeats
22
Q

how does HIV cause AID symtoms

A

infected + kills T h cells

  • T h cells cant stimulate cytotoxic T cells, B cells, phagocytes
  • immune system deteriorates
  • more susceptible to infections
  • disease that wouldnt cause serious problems in healthy immune system are deadly
23
Q

why are antibiotics ineffective against viruses

A
  • antibioticd cant enter human cells - virus exists in host cells
  • virus dont have own metabolic reactions which antibiotics target

bio (12 decks)

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