Lecture II - Mitochondria Genetics

Question 1

Idenitfy structures

Question 2

What is the Endosymbiotic theory?

Answer 2

A theory that proposes that mitochondria were once free-living bacteria. The theory states that an anaerobic eukaryote engulfed an aerobic eubacterial cell through endocytosis and that the bacterial cell eventually evolved into a mitochondria.

Question 3

How is a mitochondria similar to a prokaryotic cell?

Answer 3

Circular DNA, No histones, 70s ribosomes, and Growth via Binary Fission

Question 4

How do mitochondria segregate during mitosis? What can this lead to?

Answer 4

Randomly.. This can lead to some cells receiving only one type of organelle (all normal or all mutated) (Homoplasmy) (Usually Heteroplasmic)

Question 5

What is MERRF?

Answer 5

Myoclonic epilepsy with ragged red fibers

Question 6

What is LHON?

Answer 6

Leber’s hereditary optic neuropathy - degeneration of retinal ganglion

Question 7

What is NARP?

Answer 7

Neuropathy, ataxia, and retinitis pigmentosa

Question 8

What is KSS?

Answer 8

Kearns-Sayre syndrome - progressive weakness or paralysis of the eye muscles.

Question 9

What is CEOP?

Answer 9

Childhood epilepsy with occipital paroxysms

Question 10

What is Leigh syndrome?

Answer 10

Degeneration of the central nervous system

Question 11

What is Leigh Syndrome?

Answer 11

A rare genetic neurometabolic disorder that results from mutations in nuclear or mitochondrial genes that cause loss of function of mitochondria.

It is characterized by the degeneration of the central nervous system.

Symptoms begin between the ages of three months to a few years old. Life expectancy is a few years to mid-teens.

Question 12

How do mitochondrial diseases become “activated”?

Answer 12

Through the threshold affect. Where a certain % of the Mitochondria have to be affected before the phenotype shows itself.

Question 13

What are some basic consequences of mitochondrial DNA mutation (that are associated with aging, also remember oxidative phosphorylation declines with age)

Answer 13

hearing loss

Retinal degeneration

cardiomyopathy

Liver failure

Muscle weakness

Exercise intolerance

Question 14

What is pronuclear transfer?

Answer 14

A possible new way to help prevent the transmission of mitochondrial DNA diseases. It works by removing the nucleus of a healthy donor egg, leaving the healthy mitochondria intact, and replacing the nucleus with the mothers nucleus. This potential allows the parents to have a child who will not inherit as many of his mothers mutated mitochondria.

Question 15

What are some risks of pronuclear transfer?

Answer 15

That is will not work and the child will still inherit maternal DNA.