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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 1
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 hor... 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 1
Step 1
Step 2
2. Suggest and explain why testosterone binds to a specific AR.
Answer
Testosterone binds to a specific androgen receptor (AR) because the AR has a complementary tertiary structure that fits the testosterone molecule. This specific fit ensures that the interaction is precise, allowing the AR to effectively respond to testosterone.
Step 3
3. Suggest how the AR could stimulate gene expression.
Answer
The androgen receptor (AR) acts as a transcription factor. Upon binding with testosterone, the AR undergoes a conformational change that enables it to bind to DNA at specific promoter regions. This binding can stimulate the recruitment of RNA polymerase, which initiates transcription of target genes, thereby stimulating gene expression.
Step 4
4. What can you conclude from the data in Table 1?
Answer
With 16 or fewer CAG repeats, the probability of association with prostate cancer is significant (P = 0.02), indicating a strong correlation. For 17 to 18 repeats, the association is less significant with increasing P values (0.30 and 0.07 respectively), suggesting that as the number of repeats increases, the likelihood of developing prostate cancer decreases.
Step 5
5. What can you conclude from the data in Table 1?
Answer
For 19 or more CAG repeats, the probability values (P = 0.09 and P = 0.06) suggest weak associations with prostate cancer risk. Thus, it can be concluded that lower numbers of CAG repeats are significantly linked to a higher risk of developing prostate cancer, while higher repeats may not have the same risk factor.