new a2 question booklet

Question 1

1.1 explain how the methylation of tumour suppressor genes can lead to cancer (3)

Answer 1

• methylation prevents transcription of the gene
• protein not produced that prevents cell division / causes cell death / apoptosis
• no control of mitosis

Question 2

2.1 define what is meant by epigenetics (2)

Answer 2

• heritable change in gene function
• without changes to the base sequence of dna

Question 3

2.3 explain how increased methylation could lead to cancer (3)

Answer 3

• methylation groups (could be) added to (both copies of) a tumour suppressor gene
• the transcription of tumour suppressor genes is inhibited
• leading to uncontrolled cell division

Question 4

2.4 give one way in which benign tumours differ from malignant tumours (1)

Answer 4

• cells of benign tumours cannot spread to other parts of the body / metastasise
  OR
• cells of benign tumours cannot invade neighbouring tissues

Question 5

3.2 describe how alterations to tumour suppressor genes can lead to the development of tumours (3)

Answer 5

• (increased) methylation (of tumour suppressor genes)
• mutation (in tumour suppressor genes)
• tumour suppressor genes are not transcribed / expressed
  OR
• amino acid sequence / primary structure altered
• (results in) rapid uncontrollable cell division

Question 6

4.1 what is meant by a genome? (1)

Answer 6

(all) the DNA in a cell / organism

Question 7

4.3 use figure 8 to explain what ‘precipitated DNA’ consists of (1)

Answer 7

DNA, transcription factor and antibody

Question 8

4.5 describe the roles of two names types of enzymes used to insert DNA fragments into plasmids (2)

Answer 8

• restriction (endonuclease / enzyme) to cut plasmid / vector
• ligase joins gene / DNA to plasmid vector