Lecture 3

Question 1

What is the definition of homologous genes

Answer 1

Two genes derived from the same ancestral gene

Reveals molecular details of evolutionary change

Two sequences may be similar, but not identical due to the independent accumulation of different random mutations

Question 2

What are paralogs

Answer 2

Homologous genes within a single species

Gene duplication can lead to a gene family

• Two or more paralogs within the genome of a single organism

Example: Globin genes

Question 3

How are paralogs related to mosquitoes

Answer 3

Gene duplications in mosquitoes linked to insecticides resistance

Spraying insecticides adds a selection pressure - mosquitoes must evolve to survive

Duplications found in genes that encode for proteins in pathways targeted by insecticides

Duplications can be mutated to confer resistance or can increase production of the protein

Question 4

What is horizontal gene transfer

Answer 4

Exchange of genetic material among different species

Surprisingly common phenomenon

Can transfer:
- Prokaryotes to Eukaryotes
- Eukaryotes to Prokaryotes
- Between prokaryotes
- Between eukaryotes

Widespread among bacteria

Question 5

How does evolution occur at the genomic level

Answer 5

Involves changes in chromosome structure and number

Compares three largest chromosomes in humans and apes

• Similar due to close evolutionary relationship
• Humans have one large chromosome 2 while apes have it divided into two separate chromosomes
• Chromosome 3 very similar but orangutans have a large inversion

May have established orangutans as a new species