Mutations

Question 1

what are germ line mutations?

Answer 1

• affects gametes
• mutation transmitted via sexual reproduction
• mutations in the germline create new variation (alleles) and can be heritable

Question 2

what are somatic mutations

Answer 2

• affects all daughter cells of a single cell
• not heritable (but can be passed down in plants)

Question 3

Describe some of the smaller changes that cause mutations:

Answer 3

• single base changes (substitution)
• DNA of different sizes is inserted/deleted (in/del) into the middle of an existing sequence
  
  • if in/del isn’t a factor of 3 then frameshift occurs.

Question 4

Describe some of the larger changes that cause mutations:

Answer 4

• DNA is copied a second time or switched around
• chromosomes join together (fusion) or lost (aneuploidy)
• entire genomes duplicated

Question 5

Explain how variation is introduced?

Answer 5

• Regulatory regions: mutations of genes may affect expression
• Increase/decrease in mRNA abundance
• Coding regions: mutations of genes may affect protein function: be functionally the same, large or small functional differences

Question 6

Why is there a ‘two-sold cost of sex’?

Answer 6

• Evolution should savour asexual reproduction:
  - much faster
  - no search cast w/ finding a mate
  - no risk of STI’s
• Benefits of SR:
  - Combing beneficial alleles
  - generation of novel genotypes
  - Faster evolution

Question 7

What are some mating systems:

Answer 7

1. assortative mating (non-random)
   a. breeding like w/ like
   b. decrease genetic diversity
   c. humans, sea snails, sea slugs, etc
2. Disassortative mating (random):
   a. wolves in yellow stem
   b. not very common
   c. maintains diversity

Question 8

Define genetic drift:

Answer 8

• Random changes in allele frequencies
• Alleles become more or less common by chance
• Always an element of randomness in determining which alleles are passed on by the parental population
• allele frequencies changes via genetic drift results from sampling error.

Question 9

Buri:

Question 10

Explain the role and importance of population size:

Answer 10

• Genetic drift is most pronounced in small population size.
• P usually = 0.5
• In small populations genetic drift is a stronger enough evolutionary agent of change
• outcomes mere unpredictable
• possibility of large changes is greater
• large populations buffer genetic drift
• Bottleneck and founder effect decrease population size and genetic diversity.

Question 11

Case study on Cheetahs

Answer 11

go through notes.