Antibodies

Question 1

What are antibodies?

Answer 1

Antibodies are proteins with specific binding sites synthesised by B cells.

Question 2

How many binding sites do antibodies have?

Answer 2

• Each antibody has two identical binding sites.

* Antibody binding sites are complementary to a specific antigen.

Question 3

What are antibodies made up of?

Answer 3

• Four polypeptide chains, two pairs.
• One pair of long and called heavy chains
• Other pair is shorter and called light chains.

Question 4

What is the variable region?

Answer 4

The binding site is different on different antibodies, and thus is called the variable region.

Question 5

what does the binding site consist of?

Answer 5

A sequence of amino acids that form a specific 3-D shape that binds directly to a specific antigen.

Question 6

What is the constant region?

Answer 6

The region that isn’t the binding site, the rest of the antibody.

Question 7

What are the two ways in which the antibodies lead to the destruction of an antigen?

Answer 7

• Cause agglutination of the bacterial cells, in this way clumps of bacterial cells are formed making it easier for the phagocytes to locate them as they are less spread out within the body.
• They serve as markers that stimulate phagocytes to engulf the bacterial cells to which they are attached.

Question 8

What is a monoclonal antibody?

Answer 8

A single type of antibody that is isolated and cloned.

Question 9

How are monoclonal antibodies are used in medicatoin?

Answer 9

• Monoclonal antibodies are produced that are specific to antigens on cancer cells.
• Antibodies are given to a patient and attach themselves to the receptors on their cancer cells.
• They attach to the surface of their cancer cells, and block the chemical signals that stimulate their uncontrolled growth.

Question 10

How does indirect monoclonal antibody therapy work?

Answer 10

Attaching a radioactive or cytotoxic drug to the monoclonal antibody, when the antibody attaches to the cancer cells, it kills themselves.

Question 11

How do pregnancy tests work?

Answer 11

• Placenta produces a hormone called human chronic gonadatrophin, this is found in the urine.
• Monoclonal antibodies present on the test strip fo a home pregnancy testing kit are linked to the coloured particles, if hCG is present in the urine, it binds ot these antibodies.
• The hcG antibody colour complex moves along the strip until it is trapped by a different type of antibody created a coloured line.

Question 12

What are some ethical issues with monoclonal antibodies?

Answer 12

• Production of monoclonal antibodies involves the use of mice, these mice are used to produce both antibodies and tumour cells, some people have issues with using animals this way.
• Monoclonal antibodies have been used successfully to treat diseases, however there are deaths associated with the use in the treatment of some diseases, it is important that the patient is informed of the risks and benefits of these drugs before giving permission for them to be used, informed consent.
• Testing for new drugs present dangers, there are issues about the conduct of drug trials.