topic 8 MS answers

Question 1

why do we use base sequence rather than amino acid sequence to identify evolutionary relationships

Answer 1

more than 1 base sequence codes for the same amino acid
there are more bases than amino acids

Question 2

Suggest how the scientists found the
number of CAG repeats in the bands shown on the gel.

Answer 2

run fragments of known lengths and compare to unknown lengths

Question 3

Two bands are usually seen for each person tested. Suggest why only one
band was seen for Person L.

Answer 3

homozygous
same mass and length fragments

Question 4

The DNA probe the geneticist used was for an exon in the DNA, not an intron.
Explain why.

Answer 4

introns aren’t translated and aren’t in mRNA
mutations of exons are what affect amino acid sequence
so more important to know if persons exons are affected rather than introns

Question 5

how would the production of antisense reduce expression of sense

Answer 5

antisense mRNA comp to sense mRNA
so antisense mRNA would base pair with sense mRNA
ribosomes cant bind
so less translation of mRNA
and less production of sense

Question 6

why is dna on nylon membrane treated to form single strands

Answer 6

so dna probe can bind or anneal