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Testosterone is a steroid hormone that belongs to a group of male sex hormones called androgens - AQA - A-Level Biology - Question 2 - 2020 - Paper 2
Question 2
Testosterone is a steroid hormone that belongs to a group of male sex hormones called androgens. 1. Explain why steroid hormones are hydrophobic. 2. In the cytopla... show full transcript
Worked Solution & Example Answer:Testosterone is a steroid hormone that belongs to a group of male sex hormones called androgens - AQA - A-Level Biology - Question 2 - 2020 - Paper 2
Step 1
Explain why steroid hormones are hydrophobic.
Answer
Steroid hormones, including testosterone, are derived from cholesterol, which is lipid-soluble. This lipid solubility allows them to diffuse freely across the phospholipid bilayer of cell membranes, enabling them to enter cells without the need for specific transport proteins.
Step 2
Suggest and explain why testosterone binds to a specific AR.
Answer
Testosterone binds to a specific AR due to the complementary shapes and tertiary structure of both molecules. The AR has a unique binding site that specifically accommodates testosterone, allowing for a precise interaction that is crucial for the function of the hormone.
Step 3
Suggest how the AR could stimulate gene expression.
Answer
The AR, upon binding testosterone, undergoes a conformational change that enables it to act as a transcription factor. This change allows the AR to bind to specific DNA regions, promoting the recruitment of RNA polymerase and other necessary factors for gene transcription, thereby stimulating gene expression.
Step 4
What can you conclude from the data in Table 1?
Answer
With 16 or fewer CAG repeats, the association with prostate cancer is significant (P = 0.02). In contrast, with 17 or more CAG repeats, the probability values suggest that the association is not significant, indicating that as the number of repeats increases, the likelihood of developing cancer decreases. Thus, individuals with fewer than 16 repeats may be at greater risk of prostate cancer.