Module 4: Specfic immune response

Question 1

Describe the function of the variable region

Answer 1

Form the antigen binding sites.
Different in each antibody.
Specific to the antigen.

Question 2

Describe the function of the hinge region

Answer 2

Allows flexibility.

Question 3

Describe the function of the constant region

Answer 3

The same in all antibodies.

Allows the antibody to bind to receptors on phagocytes.

Question 4

Describe the function of the disulphide bridge

Answer 4

Holds the two heavy polypeptide chains together

Question 5

Describe the function of antibodies

Answer 5

Agglutination - Antibodies (agglutinins) can attach to 2 pathogens at the same time. Pathogens become clumped together. Phagocytes can engulf lots of pathogens at the same time.
Neutralising toxins - Anti-toxins bind to specific toxins. Prevents the toxin affecting human cells.
Prevent pathogens binding to human cells - Antibodies bind to the pathogen. Blocks the receptor that the pathogen use to bind to host cells.

Question 6

Describe the process of clonal selection and clonal expansion in T-lymphocytes

Answer 6

Each T lymphocyte has a different receptor on its surface.
Each one is complimentary to a different antigen.
The specific T lymphocyte binds to the antigen on the pathogen (clonal selection).
This activates the T lymphocyte
The T lymphocyte divides by mitosis to produce clones (clonal expansion)

Question 7

State the different types of cells that T lymphocytes can differentiate into and describe their function

Answer 7

T helper cells - release interleukins to stimulate B lymphocytes.
T killer cells - kill invaded body cells.
T regulatory cells - suppress the immune system to stop the white blood cells attacking body cells.
T memory cells - stay in the body, can differentiate quickly if the same pathogen enters the body again.

Question 8

Describe the process of clonal selection and clonal expansion in B lymphocytes

Answer 8

Each B lymphocyte has antibodies on its surface.
Each one is complementary to a different antigen.
The antibody binds to the specific antigen on the pathogen (clonal selection).
The B lymphocyte also has receptors for interleukins.
This activates the B lymphocyte.
The B lymphocyte divides by mitosis to produce clones (clonal expansion).

Question 9

State the different types of cells that B lymphocytes can differentiate into and describe their function

Answer 9

B plasma cells - produce antibodies.

B memory cells - stay in the body, can differentiate quickly if the same pathogen enters the body again.

Question 10

Primary response:

When the pathogen enters, Speed of response, length of response, activated cells, if symptoms shown.

Answer 10

First time
Slower
Shorter
B & T lymphocytes
Yes

Question 11

Secondary response:

When the pathogen enters, speed of response, length of response, activated cells, if symptoms are shown.

Answer 11

Second time
Quicker
Longer
B & T memory cells
No

Question 12

Explain why you don’t show any symptoms the second time a pathogen enters the body

Answer 12

Memory cells recognise the pathogen.
Clonal expansion and differentiation occur more quickly.
The pathogens are destroyed before they can reproduce to large numbers.