5.5 antibodies Flashcards
What are antibodies and what are they produced by
Protein with specific bonding sites synthesised by B cells.
When the body is infected by non self material, the B cell produces a specific antibody
How do the antibody and the pathogen bind
. The specific antibody reacts with an antigen on the surface of non self material
. Each antibody has two identical binding sites, and these sites are complimentary to a specific antigen
Why is there a massive variety of antibodies
Because they’re made out of proteins which can have many different sequences of amino acids so have an almost infinite number of forms
What are antibodies made of
. Two pairs so 4 peptide chains-
. where one pair have long chains so are called heavy chains
. One pair have short chains so are called light chains
What is the complex called when an antibody binds to an antigen
Antigen-antibody complex
As each antibody has a specific binding site that fits precisely onto the specific antigen
Why is the binding site of an antibody called a variable region
What is the constant region
What is the binding site made out of
It’s a variable region because it is a different shape on different antibodies
The constant region is the rest of the antibody which binds to receptors on cells eg B cells
It’s made of a sequence of amino acids that form a 3D shape
What two ways does an antibody lead to the destruction of an antigen
. Agglutination
. Markers
. Antibodies don’t destroy antigens, but they prepare it for destruction
.Agglutination of the bacterial cells: Clumps the bacterial cells together making it easier for the phagocytes to locate them as they’re less spread out within the body
. They serve as markers that stimulate phagocytes to engulf the bacterial cells to which they are attached
Where are the regions on the antibody
It’s shaped like a Y
. The two top chains are the light chains, and on the top of those are the antigen binding sites and variable region
. The bottom chains are the heavy chains and constant regions
What are monoclonal antibodies
. Any microorganism entering the body will have many antigens on it which will each induce a different B cell to multiply and form a clone of itself.
The clones will each produce a different antibody, so if one of these antibodies is isolated and cloned outside of the body, it’s monoclonal
Why can monoclonal antibodies help target medication to cells
. Since an antibody is specific to a particular antigen, monoclonal antibodies can be used to target specific substances and cells eg cancer cells.
What is one of the ways in which a monoclonal antibody can target cancer cells
Direct monoclonal antibody therapy
. Monoclonal antibodies are produced that are specific to the antigen on cancer cells
. These antibodies are given to the patient and attach themselves to receptors on their cancer cells
. They attach to the surface of their cancer cells and block the chemical signals that stimulate their uncontrolled growth
What is Herceptin
Why is direct monoclonal antibody therapy good
It is a monoclonal antibody used to treat breast cancer
Since the antibodies are not toxic, and are highly specific, they leave fewer side effects than other forms of therapy
What is the method of indirect monoclonal antibody therapy
Why are they used in smaller doses
. Attach a radioactive or cytotoxic drug ( a drug that kills cells) to the monoclonal antibody, and when the antibody attaches to cancer cells, it kills them.
They are referred to as magic bullets and can be used in smaller doses as they are targeted on specific sites.
Using them in smaller doses is cheaper and reduces any side effects the drug may have
How are monoclonal antibodies used in medical diagnosis
Eg prostate cancer
. Can diagnose diseases such as influenza, hepatitis, and chlamydia infections where they produce a more rapid result than conventional methods of diagnosis
They can also diagnose cancer eg men with prostate cancer often produce more of a protein celled PSA leading to high levels of it in the blood.
. By using a monoclonal antibody that interacts with this antigen, you can find the amount of PSA in the blood so if its higher than normal it gives a warning of the possibility of cancer
How are monoclonal antibodies used for testing for pregnancy
Pregnancy testing kits can be used at home so pregnancy is detected early.
. The placenta produces a hormone called human chorionic gonadatrophin (hCG) which can be found in the mothers urine
. Monoclonal antibodies specific to the antigen of hCG are on the test strip and are linked to coloured particles
. So if hCG is present it binds to these antibodies and a HCG-antibody-colour complex moves along the strip until it is trapped by a different type of antibody, creating a coloured line
