Immune system

Question 1

molecules lymphocytes identify

Answer 1

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

Question 2

antigens

Answer 2

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

Question 3

Antigenic variability

Answer 3

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

Question 4

physical barriers

Answer 4

skin
stomach acid
lysozymes in tears

Question 5

phagocytes

Answer 5

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

Question 6

T lymphocytes

Answer 6

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

Question 6

Antigen-presenting cells

Answer 6

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

Question 7

role of T helper cells

Answer 7

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

Question 8

role of cloned T helper cells

Answer 8

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

Question 9

Cytotoxic T cells

Answer 9

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

Question 10

B lymphocytes

Answer 10

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

Question 10

B memory cells

Answer 10

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

Question 10

Humoral response

Answer 10

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

Question 11

Antibodies

Answer 11

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

Question 12

Antibody structure

Answer 12

Antigen binding sites
variable region
constant region

Question 13

Agglutination

Answer 13

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

Question 13

passive immunity

Answer 13

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

Question 14

active immunity

Answer 14

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

Question 15

Natural active immunity

Answer 15

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

Question 16

Artificial active immunity

Answer 16

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

Question 17

Vaccinations

Answer 17

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

Question 18

primary vs secondary response

Answer 18

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

Question 18

Herd immunity

Answer 18

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

Question 19

monoclonal antibodies

Answer 19

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

Question 20

uses of monoclonal antibodies

Answer 20

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

Question 21

pregnancy test

Answer 21

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

Question 22

purpose of ELISA test

Answer 22

Detect the presence and quantity of antigen used for medical diagnosis

Question 23

HIV structure

Answer 23

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

Question 24

ethical issues with monoclonal antibodies

Answer 24

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

Question 25

HIV replication

Answer 25

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

Question 26

Auto immunodeficiency syndrome (AIDs)

Answer 26

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

Question 27

why vaccines may be unsafe

Answer 27

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

Question 28

role of antibodies in ELISA

Answer 28

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

Question 29

why do you wash well in ELISA

Answer 29

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

Question 30

why are antibiotics ineffective against viruses?

Answer 30

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

Question 31

pathogen

Answer 31

microorganisms that cause a disease by releasing toxins or killing cells

Question 32

cytokinesis

Answer 32

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

Question 33

uncontrolled mitosis

Answer 33

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

Question 34

viral replication

Answer 34

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

Question 35

cell adaptations for rapid transport across membranes

Answer 35

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

Question 36

Antigen- antibody complex

Answer 36

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