Humoural Response (B cells/ plasma cells/ antibodies.)

Question 1

What is the “humoural response?”

Answer 1

• Humoural response is the response of B lymphocytes to a foreign antigen, clonal selection and the release of monoclonal antibodies.

Question 2

How are B cells activated and how do they divide?

Answer 2

• Complementary antigen will collide with B cell. B cell will take in antigen/ present the speciic antigen on its surface membrane.
• B cell will collide with receptor on helper T cell, activating B cell to go through differentiation/ clonal selection.
• Undergo mitosis: making large no of plasma/ memory B cells.

Question 3

What is “clonal selection?”

Answer 3

• When B lymphocytes differentiate into either plasma cells OR memory B cells.

Question 4

What do plasma cells and memory B cells do?

Answer 4

• Plasma cells: produce antibodies/ release them into bloodstream.
• Memory B cells: can divide rapidly into plasma cells when re-infected with same pathogen to make more antibodies a lot more quickly!!

Question 5

True or False

Memory B cells make antibodies.

Answer 5

• False.
• Memory B cells don’t make antibodies, they divide by mitosis and differentiate into plasma cells rapidly if they collide with antigen they have already encountered.

Question 6

True or False

Plasma cells remain in the bloodstream for decades.

Answer 6

• False.
• Plasma cells are short-lived but, memory B cells will remain in the blood for a long period of time!

Question 7

What are the two different immune responses called, when pathogen enters body for 1st time/ when pathogen enters for 2nd time?

Answer 7

• Primary immune response
• Secondary immune response.

Question 8

What are antibodies?

Answer 8

• Antibodies are soluble proteins released by B lymphocytes.
• They are quarternary structure proteins (have multiple polypeptide chains.)

Question 9

What is the structure of antibodies like?

Answer 9

• Has 4 polypeptide chains. 2 light chains, 2 heavy chains.
• Has constant regions (will be same in all antibodies.)
• Has varibale regions (every antibody has different variable region - complementary to specific antigen.)
• Disulphide bridges (between heavy chains) provides stability and joins the polypeptide chains together.

L2 Immune system (black arch file school folder) –> you will find a diagram.

Question 10

What allows the variable region of antibody to have a specific shape?

Answer 10

• Variable region has specific amino acid sequence, which means shape of binding site is complementary to specific antigen.

Question 11

How will antibodies actually help to destroy an antigen/ pathogen?

Answer 11

• Antidbodies will bind to specific comp antigen, forming antigen-antibody complex.
• The antibodies will bind to multiple antigens at once - causing the pathogens to clump together: AGGLUTINATION.
• This will enhance phagocytosis.