Mitochondrial

Question 1

mitochondrial DNA

Answer 1

circular DNA

16569 bp

37 genes : 22 tRNA, 2 ribosomal RNA( 16s and 12s) and 13 proteins/polypeptides

all 13 poly peptides are subunits of enzymes involved in oxidative phosphorylation (energy through electron transfer chain)

Question 2

electron transport chain II

Answer 2

complex I NADH dehydrogenase complex

complex II Succinate dehydrogenase complex

complex III coenzyme Q passes on electrons to complex III which consist of cytochrome B and C

Complex IV the electron next pass on to cytochrome oxidase complex where molecular oxygen is the terminal electron acceptor

Question 3

Complex I

Answer 3

NADH dehydrogenase produces 7 peptides

Question 4

complex II

Answer 4

Succinate dehydrogenase

Question 5

complex III

Answer 5

coenzyme Q passes on electrons to complex III which consist of cytochrome B and C

Question 6

complex IV

Answer 6

the electron next pass on to cytochrome oxidase complex where molecular oxygen is the terminal electron acceptor

3 peptides for cytochrome C oxidase are COI, II and III

Question 7

types of mtDNA mutations

Answer 7

mis-sense mutation for genes that alter the activity of a OXPHOS protein

pont mutation in tRNA or rRNA molecules

rearrangements that generate deletions or duplications in the genome

Question 8

correlation of anaerobic threshold and phenotype

Answer 8

lower anaerobic threshold has more sever phenotypes

Question 9

mitochondrial inheritance

Answer 9

entirely maternal no child of a father with mutation will cary same mutation

mature oocyte carries aprox 100000 copies of mtDNA

sperm contain just a few which are in tail and is shed upon fertilization

Question 10

genetic bottleneck effect

Answer 10

loss of genetic variability in a population after a reduction in population size

Question 11

heteroplasmy

Answer 11

with every replication mitochondria segregates in a bottleneck type way and can cause an increase or decrease in mutated mitochondria in daughter cells causing a range in phenotypes

heteroplasmy = mitochondrial mutations vary

homoplasmy= mitochondrial dna is homogeneous

Question 12

LHON( leber’s hereditary optic neuropathy)

Answer 12

type of blindness =mutations in peptides of coplex I

nadh dehydrogenase mutations

has to be homoplasmy

Question 13

NARP(Leigh disease)

Answer 13

mutations of complex V proteins = mutation `ATPase subnit 6

can be hetroplasmy (variable phenotype)

Question 14

MERRF

Answer 14

tRNA for lysine

hetroplasmic

Question 15

MELAS

Answer 15

tRNA for Leucine

hetroplasmic

Question 16

CEPO and KSS

Answer 16

mutation through large deletions

can be heteroplasmic

sporatic inheretince (all mutations are new mutations as mutated mutations dont typically survive to get passed on)

Question 17

autosomally transmitted deletions in mtDNA

Answer 17

a syndrome resembling CPEO

more than one nuclear gene may be respnnsible for the integrity of normal mtDNA

autosomal dominant and recessive form of syndrome have been observed

Question 18

mitochondrial DNA depletion syndrome

Answer 18

autosomally transmitted

characterized by reduced quantity of mtDNA

atleast one nuclear gene controls the abundnce of mtDNA

Question 19

The mitochondrial disorders MELAS (mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes) and MERRF (myoclonic epilepsy with ragged red fibers) are generally both caused by what type of mutation?

Answer 19

Single base mutations in the mitochondrial tRNA genes

Question 20

The tissues that are most affected by mtDNA mutations have high requirements for which of the following?

Answer 20

Metabolic energy