Gene expression and cancerAQA A-Level Biology: Flashcards

Exam questions on Gene expression and cancer

1. A surgeon removes lumps from two different patients. Lump A grew slowly, was surrounded by a capsule and contained cells that looked similar to normal cells. Lump B grew rapidly, had no capsule and contained cells with large dark nuclei and very different sizes. Cells identical to those in lump B were later found in nearby lymph nodes.
   Explain why lump B is more life-threatening than lump A.2 marks
2. Cell division in a tissue is controlled by two genes. The protein from gene X stimulates cells to divide. The protein from gene Y slows cell division and can cause a damaged cell to die. In tumour 1 the gene X protein was active all the time. In tumour 2 the promoter region of gene Y was heavily methylated.
   Explain how the changes in tumour 1 and tumour 2 could each lead to uncontrolled cell division.2 marks
3. Some breast cancers grow faster when the concentration of oestrogen is high. The cells of these tumours have oestrogen receptors. Researchers have designed a drug with a shape similar to oestrogen that binds to the receptor but does not activate it.
   Explain how an increased concentration of oestrogen can contribute to the development of some breast cancers.3 marks