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

What is “clonal selection?”

Answer 2

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

Question 3

What do plasma cells and memory B cells do?

Answer 3

• 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 4

True or False

Memory B cells make antibodies.

Answer 4

• 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 4

True or False

Plasma cells remain in the bloodstream for decades.

Answer 4

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

Question 5

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

Answer 5

• Primary immune response
• Secondary immune response.

Question 6

What are antibodies?

Answer 6

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

Question 7

What is the structure of antibodies like?

Answer 7

• 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 8

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

Answer 8

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

Question 9

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

Answer 9

• 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.

Question 10

What do B cells have on their cell-surface membrane?

Answer 10

• Specific antibodies that will bind to specific antigen.

Question 11

What is the name of the complex formed when antibody binds to anitgen?

Answer 11

Antigen-antibody complex

Question 12

Exam Q

Describe how B lymphocytes would respond to virus vaccination (do not include cellular response in answer.)

Answer 12

• B cell antibody (on its surface) binds to complementary antigen of virus.
• B cell will divide by mitosis rapidly - forming clones.
• Clones will differentiate into plasma cells/ memory cells (clonal selection.)
• Plasma cells produce antibodies (comp to antigens on surface of virus.)