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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
In the box provided, the typical representation of an antibody consists of four polypeptide chains. These include the two heavy chains and two light chains, which are linked by disulfide bonds. The structure should depict a Y-shape where the upper arms represent the variable regions that bind to the 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
Using arrows, mark the tips of the upper arms of the Y-shaped antibody structure. These tips correspond to the antigen-binding sites, where specific interactions with antigens occur.
Step 3
b. Outline the general characteristics of an autoimmune disease.
Answer
An autoimmune disease is characterized by the body's immune system mistakenly identifying its own cells as foreign. Consequently, it attacks and destroys these self cells. This misidentification can lead to a variety of symptoms and complications, depending on the type of cells affected. Examples include chronic inflammation and tissue damage.
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 biochemical substance produced by specialized cells or glands that is released into the bloodstream and regulates physiological processes in other cells or organs. Hormones can have diverse effects on growth, metabolism, immune function, and maintain homeostasis throughout the body.
Step 5
d. Design an experiment to test the scientist’s prediction.
Answer
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State the hypothesis that you are testing: 'Administering vitamin D supplements will reduce the incidence and severity of rheumatoid arthritis in laboratory mice.'
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Outline the experimental procedure that you follow:
- Select a group of laboratory mice that typically develop rheumatoid arthritis.
- Divide them into two groups: one group receiving vitamin D tablets and a control group receiving a placebo.
- Monitor both groups over a set period, noting any development of arthritis symptoms using standardized scoring.
- Collect blood samples to measure vitamin D levels and immune markers related to arthritis development.
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Describe results that would support your hypothesis:
- A significant reduction in the incidence and/or severity of arthritis symptoms in the vitamin D group compared to the control group would support the hypothesis.
- Additionally, higher vitamin D levels in the treatment group, along with lower immune markers related to inflammation, would further substantiate the findings.