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Alevel Biology > Immune system > Flashcards

Immune system Flashcards

1
Q

molecules lymphocytes identify

A

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

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2
Q

antigens

A

proteins on the cell-surface membrane
trigger an immune response when detected by lymphocytes

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3
Q

Antigenic variability

A

When pathogenic DNA mutates
causing a change in shape of
antigen
previous immunity is no longer effective as memory cells don’t recognise new shape of antigen.
specific antibody no longer
binds to new antigen

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4
Q

physical barriers

A

skin
stomach acid
lysozymes in tears

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5
Q

phagocytes

A

non-specific immune response
phagocytes become antigen-presenting cells after destroying pathogen

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6
Q

T lymphocytes

A

made in bone marrow and mature in thymus gland
involved in cell-mediated immune response
respond to antigen-presenting cells

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6
Q

Antigen-presenting cells

A

Any cell that presents a non-self antigen on their surface
infected body cells
macrophage after phagocytosis
cells of transplanted organ
cancer cells

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7
Q

role of T helper cells

A

have receptors on their surface that attach to antigens on ACP
become activated - clonal selection

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8
Q

role of cloned T helper cells

A

some remain as helper T cells and activate B lymphocytes
stimulate macrophages for phagocytosis
become memory cells for that shaped antigen
become cytotoxic killer T cells

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9
Q

Cytotoxic T cells

A

destroy abnormal/ infected cells by releasing perforin
so that any substances can enter or leave the cell and this causes cell death

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10
Q

B lymphocytes

A

made in bone marrow and mature in bone marrow
involved in humoral immune response
involves antibodies

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10
Q

B memory cells

A

derived from B lymphocytes
remember specific antibody for particular antigen
will rapidly divide by mitosis and differentiate in plasma cells upon secondary encounter
resulting in large numbers of antibodies rapidly

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10
Q

Humoral response

A

APC activates B cells
B cell undergoes clonal selection and expansion - rapid division by mitosis
differentiate into plasma cells/ memory B cells
plasma cells make antibodies

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11
Q

Antibodies

A

quaternary structure proteins made of 4 polypeptide chains
different shaped binding sites = variable regions
complementary to a specific antigen

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12
Q

Antibody structure

A

Antigen binding sites
variable region
constant region

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13
Q

Agglutination

A

Antibodies have 2 binding sites and are flexible - clumps pathogens together
makes it easier for phagocytes to locate and destroy pathogen

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13
Q

passive immunity

A

antibodies introduced into body
plasma and memory cells not made as no interaction with antigen
short-term immunity
fast acting

14
Q

active immunity

A

immunity created by own immune system - antibodies made
exposure to antigen
Plasma and memory cells made
long term immunity
slower acting

15
Q

Natural active immunity

A

after direct contact with pathogen through infection
body creates antibodies and memory cells

16
Q

Artificial active immunity

A

creation of antibodies and memory cells following introduction of an attenuated pathogen or antigens
vaccination

17
Q

Vaccinations

A

Small amounts of dead of attenuated pathogens injected/ ingested
humoral response activated
memory cells are able to divide rapidly into plasma cells when re-infected

18
Q

primary vs secondary response

A

Primary = first exposure to the pathogen
longer time for plasma cell
secretion & memory cell
production
for the secondary response,
memory cells divide rapidly into plasma cells
so a large number of antibodies
made rapidly upon reinfection

18
Q

Herd immunity

A

when enough of the population is vaccinated so pathogen is not transmitted and spread easily
provides protection for those without vaccine

19
Q

monoclonal antibodies

A

a single type of antibody that can be isolated and cloned
antibodies that are identical - from 1 type of B lymphocyte
complementary to only 1 antigen

20
Q

uses of monoclonal antibodies

A

medical treatment - targeting drugs by attaching antibody complementary to tumour cell antigen
medical diagnosis - pregnancy test

21
Q

pregnancy test

A

ELISA test which uses 3 monoclonal antibodies and enzymes to test for hCG

22
Q

purpose of ELISA test

A

Detect the presence and quantity of antigen
used for medical diagnosis

23
Q

HIV structure

A

core = RNA and reverse transcriptase
capsid = protein coat
lipid envelope taken from hosts cell membrane
attachment proteins so it can attach to helper T cells

24
Q

ethical issues with monoclonal antibodies

A

requires mice to produce antibodies and tumour cells
requires a full cost-benefit analysis

25
Q

HIV replication

A

attaches to CD4 receptor on helper T cells
protein fuses with membrane allowing RNA and enzymes to enter

26
Q

Auto immunodeficiency syndrome (AIDs)

A

when HIV has destroyed too many T helper cells, host is unable to produce adequate immune response to other pathogens
host susceptible to opportunistic infection

27
Q

why vaccines may be unsafe

A

inactive virus may become active - viral transformation
non-pathogenic virus can mutate and harm cells
side effect of immune response
people may test positive for disease

28
Q

role of antibodies in ELISA

A

first antibody added is complementary to antigen in well - attaches
second antibody with enzyme added which attaches to first antibody as complementary.
when substrate solution added enzyme can produce colour change

29
Q

why do you wash well in ELISA

A

removes unbound 2nd antibodies
otherwise enzymes may be present = colour change = false positive

30
Q

why are antibiotics ineffective against viruses?

A

viruses are inside host cells where antibiotics cannot reach
antibiotics affect parts of bacteria that viruses dont have

31
Q

pathogen

A

microorganisms that cause a disease by releasing toxins or killing cells

32
Q

cytokinesis

A

Final stage in the cell cycle
when the cytoplasm splits in 2
creates 2 new cells

33
Q

uncontrolled mitosis

A

uncontrolled cell division can lead to the formation of tumour and of cancers
many cancer treatments are directed at controlling the rate of cell division

34
Q

viral replication

A

following injection of their nucleic acid
the infected host cell replicates the virus particles

35
Q

cell adaptations for rapid transport across membranes

A

increase in surface area or membrane
increase in the number of protein channels and carrier molecules in the membrane

36
Q

Antigen- antibody complex

A

when a complementary antibody binds to an antigen
this clumps pathogens together

Alevel Biology (14 decks)

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