specific immune system

Question 1

what are antibodies

Answer 1

• glycoproteins called immunoglobulins
• bind to specific antigen on pathogen that has triggered the immune response

Question 2

what are antibodies made up of

Answer 2

• 2 identical long polypeptide chains (heavy chains)
• 2 identical short chains (light chains)
• chains held together by disulfide bridges
• polypeptide chains also held together by disulfide bridges

Question 3

what is the binding site of an antibody

Answer 3

• area of 110 amino acids
• variable region- has a different shape on each antibody which gives it specificity

Question 4

constant region of an antibody

Answer 4

the rest of the antibody molecule which is always the same (excluding the binding site which is the variable region)

Question 5

how do antibodies defend the body

Answer 5

• antigen-antibody complex acts as an opsonin so the complex is engulfed by phagocytes
• pathogens cannot invade cells whilst in an antigen-antibody complex
• antibodies act as agglutinins causing pathogens carrying antigen-antibody complexes to clump together which prevents them spreading and makes it easier for phagocytes to engulf them
• antibodies act as anti-toxins and bind to toxins to make them harmless

Question 6

where do T lymphocytes and B lymphocytes mature

Answer 6

T lymphocytes- thymus gland
B lymphocytes- bone marrow

Question 7

T helper cells

Answer 7

• have CD4 receptors which bind to antigens on APCs
• produce interleukins (type of cytokine) which:
• stimulate activity of B cells which increases antibody production
• stimulates production of other T cell types
• attracts/stimulates macrophages to ingest pathogens with antigen-antibody complexes

Question 8

T killer cells

Answer 8

• destroy pathogen carrying the antigen
• produce hydrogen peroxide and perforin which kills pathogen by making holes in cell membrane

Question 9

T memory cells

Answer 9

• live for a long time
• part of immunological memory
• when they meet antigen the 2nd time, they divide rapidly to form clones of T killer cells

Question 10

T regulator cells

Answer 10

• suppress, control, regulate immune system
• stop immune response once pathogen dies
• make sure body recognises self antigens and does not set up autoimmune response
• interleukins also help control this

Question 11

Plasma cells (type of B lymphocyte)

Answer 11

• produce antibodies to particular antigen
• only lives for a few days

Question 12

B effector cells

Answer 12

divide to form plasma cell clones

Question 13

B memory cells

Answer 13

• live for a long time
• part of immunological memory
• remember specific antigen and enable body to respond rapidly when antigen is encountered again
• divide to form plasma cell clones

Question 14

clonal selection

Answer 14

the selection of a specific lymphocyte after exposure to specific antigen

Question 15

clonal expansion

Answer 15

proliferation (rapid increase in numbers) of specific cells with the appropriate antibody for the antigen