8 -Gene mutations and cancer

Question 1

Mutation answer structure

Answer 1

1 - Type of mutation definition
2 - Causes frameshift / or not from point of mutation
3 - 1 or all codons change point of mutation
4 - Change in DNA sequence
5 - Change in mRNA sequence - Change in tRNA sequence
6 - Amino acid sequence/ primary structure to change
7 - Hydrogen/ionic bonds form in diff places
8 - Tertiary structure changes
9 - If enzyme - Active site changes - no ES complexes - substrate not complementary

Question 2

Positive effects of mutation

Answer 2

• Causes variation in populations which can increase survival chance - basis for natural selection and evolution

Question 3

Negative effects of mutation

Answer 3

• Genetic disorders

Question 4

Mutagenic agents

Answer 4

• Factor which increases frequency of mutations
• high energy ionising radiation such as X-rays, ultraviolet rays, alpha beta or gamma rays from radioactive sources
• Chemicals such as benzene, tar in cigarettes

Question 5

Acquired mutations

Answer 5

• Mutations that occur spontaneously or caused by mutagenic agents
• Not passed to offspring

Question 6

Hereditary mutations

Answer 6

• Mutations which are present in gametes
• Offspring inherit mutation when gametes fuse during fertilisation
• When fertilised egg divide by mitosis - genetically identical daughter cells - all contain mutanMelt DNA

Question 7

How does tumour cells differ from normal cells

Answer 7

• Nucleus is larger and darker
• Irregular shape (not uniform)
• Different antigens on surface
• Don’t respond to regulatory processes
• Divide by mitosis more frequently

Question 8

What is a metastasis

Answer 8

• Tumour that has spread to bloodstream or lymphatic system so can spread to other parts of the body causing secondary tumours there - these are more difficult to treat

Question 9

Which two genes is rate of cell division controlled by

Answer 9

• Proto-oncogene codes for proteins which stimulates cell division however mutated version - oncogene- stimulates cells to divide too quickly
• Tumour suppressor gene codes for protein which inhibits cell division - mutated version prevent formation or protein so mitosis isn’t inhibited - rate increases

Question 10

Methylation of DNA

Answer 10

• Methyl (CH3) is added onto DNA
• Inhibits transcription