Lecture 15 - Mitochondria Genetics

Question 1

What is the endosymbiosis theory of mitochondria origin?

L15 S17

Answer 1

Eukaryotic cell engulfed an aerobic bacterium. The bacterium stayed in the eukaryote and eventually evolved into mitochondria.

Question 2

Compare characteristics of prokaryotes, eukaryotes, and mitochondria.

L15 S18

Answer 2

Prokaryote:

• circular DNA
• no histones
• 70S ribosome
• binary fission

Eukaryote:

• linear DNA
• histones
• 80S ribosome
• mitosis

Mitochondria:

• circular DNA
• no histones
• 70S ribosome
• binary fission

Question 3

How do mitochondria segregate during cell division? What impact can this have?

L15 S20

Answer 3

Mitochondria segregate independently, because of this, some cells may receive only mutant mitochondria or obtain a level of mitochondria that exceeds threshold for disease.

Question 4

What is the suspected reason that human mitochondria is much more efficient with DNA that organisms like yeast?

L15 S24-25

Answer 4

It is suspected that some crucial genes were moved to the nucleus where mutation rates are significantly lower.

Question 5

When do most mitochondrial disease manifest and why do they manifest at that time?

L15 S30

Answer 5

mtDNA accumulates damage with age. Most mitochondrial diseases occur in middle age and are associated with decreased oxidative phosphorylation.

Question 6

What is pronuclear transfer?

L15 S34-35

Answer 6

Nucleus from an egg with diseased mitochondria is extracted and introduced to an egg with healthy mitochondria and no nucleus. The new egg is then fertilized with sperm.

This embryo contain DNA from 3 individuals from the egg nucleus, sperm, and mitochondria.