0319 - Mitochondrial genome and mutations - EG

Question 1

What are some features of the mitochondrial genome?

Answer 1

Small genome of 16.5kbCircular37 genes involved in: oxidative phosphorylation, electron transport chain (complexes I, III, IV, V), mitochondrial protein synthesis, RNAs.

Question 2

How is the mitochondrial genome inherited?

Answer 2

Maternal inheritance

Question 3

Why do mutations occur in the mitochondrial genome?

Answer 3

• there are no repair mechanisms in mtDNA- there is an increase in free radicals released during OxPhos

Question 4

Name and describe a mitochondrial linked disease that affects vision.

Answer 4

Leber’s hereditary optic neuropathy (LHON); point mutation in the mtDNA gene that codes for complex I in the electron transport chain, leads to a buildup of reactive oxygen species, that cause apoptosis in retinal ganglion cells, and loss in peripheral vision due to the death of peripheral receptors.

Question 5

Define penetrance

Answer 5

the probability that a given phenotype will appear given that the phenotype related genotype is present.

Question 6

Define expressivity

Answer 6

the variations in a phenotype among individuals carrying a particular genotype.