Compare membrane-receptor peptide signalling with intracellular steroid receptors, then trace second messengers or transcription factors through gene regulation and cell responses.
The scientific article you have studied is adapted from an article in Clinical Nutrition entitled Muscle tissue changes with aging (July 2004). Use the information from the scientific article and your own knowledge to answer the following questions.
Testosterone is a steroid hormone. Describe how reduced production of testosterone in the male testes can result in reduced muscle protein (paragraph 5).
A description that includes the following points:
- Iower testosterone concentration in the blood (1)
- less testosterone \{enters (muscle) cell / crosses membrane / present in (muscle) cell nucleus\} (1)
- forming fewer \{hormone-receptor complexes / transcription factors\} (1)
- (therefore) reduced \{transcription / translation\} (of muscle protein) (1)
to get full marks they have to mention reduced / less / fewer at least ONCE or it is max 3 marks
accept less testosterone in blood
accept less testosterone diffuses into (muscle) cell
accept fewer muscle protein genes activated accept less testosterone binds to receptor
accept less mRNA produced ignore protein synthesis unqualified