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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. Steroid hormones are hydrophobic. Explain why steroid hormones ... 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 can rapidly enter a cell by passing through its cell-surface membrane.
Answer
Steroid hormones, including testosterone, are hydrophobic and lipid-soluble. This property allows them to easily diffuse through the lipid bilayer of the cell membrane, facilitating their rapid entry into the cell without the need for specific transport mechanisms.
Step 2
Suggest and explain why testosterone binds to a specific AR.
Answer
Testosterone binds to a specific androgen receptor (AR) because AR has a complementary tertiary structure that matches the shape of testosterone. This specificity is crucial for effective binding and subsequent biochemical responses, as only the correct ligand can induce a change in the receptor's conformation.
Step 3
Suggest how the AR could stimulate gene expression.
Answer
The binding of testosterone to the AR activates it as a transcription factor. The conformational change allows the AR to bind to specific DNA sequences in the promoter regions of target genes, resulting in the initiation of transcription and stimulation of gene expression.
Step 4
What can you conclude from the data in Table 1?
Answer
From Table 1, it can be concluded that there is a significant association between the number of CAG repeats in the AR gene and the risk of developing prostate cancer. Specifically, for individuals with fewer than 16 CAG repeats, the probability of developing cancer is low (0.02), whereas for 17 or more repeats, the association is not significant as indicated by P values greater than 0.05.