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A typical antibody molecule comprises four polypeptide chains that are linked together - VCE - SSCE Biology - Question 6 - 2008 - Paper 1
Question 6
A typical antibody molecule comprises four polypeptide chains that are linked together. The following diagram shows the four fragments of a particular antibody molec... show full transcript
Worked Solution & Example Answer:A typical antibody molecule comprises four polypeptide chains that are linked together - VCE - SSCE Biology - Question 6 - 2008 - Paper 1
Step 1
i. Redraw these fragments in the box above to show the typical representation of an antibody.
Answer
To redraw the antibody, I would represent it as a Y-shaped molecule with two heavy chains and two light chains. The heavy chains would be represented as the longer arms of the Y, while the light chains would form the shorter arms. The upper portions of the Y would consist of variable regions responsible for binding to specific antigens.
Step 2
ii. On your answer to part i, in the box above, draw two arrows to indicate the two positions at which antigen would bind to the antibody.
Answer
I would label the tips of the Y with two arrows, indicating the binding sites for the antigen. These sites are located at the 'V' regions of each arm of the antibody, where the specific interaction with the antigen occurs.
Step 3
b. Outline the general characteristics of an autoimmune disease.
Answer
An autoimmune disease is one in which the body's immune system mistakenly recognizes its own cells as foreign and mounts an immune response against them. This can lead to inflammation, tissue damage, and impairment of the affected organs.
Step 4
c. Write a new definition for a hormone, covering the majority of situations in which we know hormones are involved.
Answer
A hormone is a chemical messenger produced by glands in one part of the body that travels through the bloodstream to target cells or organs in another part of the body and elicits specific physiological effects.
Step 5
d. Design an experiment to test the scientist’s prediction.
Answer
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State the hypothesis: The deficiency of vitamin D increases the development of rheumatoid arthritis in laboratory mice, and treatment with vitamin D tablets will reduce the prevalence of the disease.
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Outline the experimental procedure: Divide mice into two groups: a control group that receives no vitamin D and an experimental group that receives vitamin D supplements. Monitor the development of rheumatoid arthritis in both groups over a specified period.
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Describe results that would support your hypothesis: A significant reduction in the incidence of rheumatoid arthritis in the experimental group compared to the control group would support the hypothesis.