Genomes, Mutations And Molecular Pathways

Question 1

Genetic variation

Answer 1

Describes the differences between the DNA sequences of individual genomes

Question 2

Origins of genetic variation

Answer 2

Ionising radiation, endogenous sources, chemicals, lower energy radiation

Question 3

C –> T transitions

Answer 3

Deamination of cytosine produces uracil, which is then repaired, however some cytosine are naturally methylated so when deamination occurs forms thymine which will not be repaired, subsequent replication forms TA base pairing

Question 4

Synonymous mutation

Answer 4

Single base substitution which changes a codon into another which codes for the same amino acid

Question 5

Non synonymous mutation

Answer 5

Single base mutation - changes the codon into another that specifies a different amino acid

Question 6

Nonsense mutations

Answer 6

Non synonymous mutation - replaces an amino acid with a STOP codon - results in unstable RNA or a truncated protein

Question 7

Missense mutation

Answer 7

Replaces on amino acid for another - effect greatest when replacement has very different physiochemistry

Question 8

Splice site mutations

Answer 8

Non synonymous mutations - Create or destroy splicing signals

Question 9

Single base substitutions

Answer 9

Mutations in regulatory DNA sequences - can effect where and when a gene is active and the level of gene activity