antibodyu

Question 1

Learn how to draw and label a antibody

Question 2

A tick is a small animal that bites humans and feeds on their blood. This results in proteins from the tick saliva entering the human body.

Scientists have suggested one hypothesis for the allergic reaction to alpha-gal in red meat. They think that an earlier immune response to a tick bite can cause a person to have an allergic reaction to alpha-gal in red meat.

Suggest how one antibody can be specific to tick protein and to alpha-gal

Answer 2

(Part of tick protein and alpha-gal) have a similar shape/structure;

Accept ‘(Part of tick protein and alpha-gal) have the same shape/structure.’

Do not credit reference to similar/same tertiary structure’.

Ignore reference to alpha-gal being a protein.

2. Antibody is complementary to both (tick protein and alpha-gal)

Question 3

Explain why antibody A attaches only to the protein found in species of Plasmodium

Answer 3

Antibody has tertiary structure;

2. Complementary to binding site on protein.

Question 4

Malaria is a disease caused by parasites belonging to the genus Plasmodium. Two species that cause malaria are Plasmodium falciparum and Plasmodium vivax.

A test strip that uses monoclonal antibodies can be used to determine whether a person is infected by Plasmodium. It can also be used to find which species of Plasmodium they are infected by.

• A sample of a person’s blood is mixed with a solution containing an antibody, A, that binds to a protein found in both species of Plasmodium. This antibody has a coloured dye attached.
• A test strip is then put into the mixture. The mixture moves up the test strip by capillary action to an absorbent pad.
• Three other antibodies, B, C and D are attached to the test strip. The position of these antibodies and what they bind to is shown in Figure 1.

Antibody B is important if this test shows a person is not infected with Plasmodium.

Explain why antibody B is important.

Answer 4

Prevents false negative results;

2. (Since) shows antibody A has moved up strip / has not bound to any Plasmodium protein.

Question 5

When a vaccine is given to a person, it leads to the production of antibodies against a disease-causing organism. Describe how.

Answer 5

Vaccine contains antigen from pathogen;

2. Macrophage presents antigen on its surface;
3. T cell with complementary receptor protein binds to antigen;
4. T cell stimulates B cell;
5. (With) complementary antibody on its surface;
6. B cell secretes large amounts of antibody;
7. B cell divides to form clone all secreting / producing same antibody.