GEN: Mitochondrial genetics

Question 1

how is energy produced in mitochondria?

Answer 1

oxidative phosphorylation

Question 2

what are some mitochondrial functions?

Answer 2

• apoptotic cell death
• Intracellular signalling
• lipid metabolism
• thermogenesis
• cellular energy production

Question 3

do mitochondria have their own DNA?

Answer 3

yes

Question 4

what do mitochondrial genes code for?

Answer 4

protein of OXPHOS chain

Question 5

what does mitochondrial genome code for?

Answer 5

13 polypeptides, 22 transfer RNAs, 2 ribosomal RNAs

• 13 polypeptides forms part of the electron transport chain?
• 2 ribosomal RNA forms mitochondria specific ribosome for translation of 13 proteins (+ 22 tRNAs)

Question 6

how is mitochondrial dna inherited

Answer 6

maternally

Question 7

mitochondrial mutations follow what 2 paths?

Answer 7

homoplasmys heteroplasmys

Question 8

what is the difference between homoplasmys and heteroplasmys?

Answer 8

Question 9

which one out of homoplasmys and heteroplasmys can arise de-novo

Answer 9

heteroplasmys

Question 10

what are the mitochondrial stop codons?

Answer 10

AGG and AGA

Question 11

what does mitochondrial function rely on?

Answer 11

proteins coded for in both mitochondrial and nuclear DNA

Question 12

what are the general features of mitochondrial disorders?

Answer 12

• Respiratory chain deficiency
• Reduced cellular oxygen consumption and ATP synthesis.
• Increased lactic acid in blood and cerebral fluid.
• Overproduction of reactive oxygen species (ROS).

Question 13

what are the three categories for mitochondrial disorders?

Answer 13

1. nuclear origin
2. nuclear origin with mitochondrial dysfunction
3. mitochondrial origin

Question 14

what is an example of a disease that follow same inheritance patterns as Mendelian disorders and can be caused by defects to genes involved in replication, transcription,
translation and repair of MT DNA.

Answer 14

Friedreich Ataxia

Question 15

whats an example of a mitochondrial disease caused by nuclear genome mutations, with mitochondria dysfunction dependence

Answer 15

Parkinson’s Disease

Question 16

what is an example of a mitochondrial disorders caused by mutations in mitochondrial genome

Answer 16

Leber’s hereditary optic neuropathy (LHON)

Question 17

what is the threshold model?

Answer 17

Question 18

do you expect the genetic code of all mitochondria to be identical?
A) the DNA of every mitochondria in the body will be identical
B) the DNA of every mitochondria in a cell will be identical, but this may vary across cells
C) the DNA of each mitochondria may be different

Answer 18

C) the DNA of each mitochondria may be different

Question 19

two siblings (one male and one female) both have the same inherited genetic disorder, could this be of mitochondrial origin?
A) no as males cannot inherit mitochondrial diseases
B) no, as both siblings are unlikely to have inherited the same mutation from the mother
C) yes as both offspring could have inherited the mutation from the mother

Answer 19

C) yes as both offspring could have inherited the mutation from the mother

Question 20

a disease presentation looks like it involved mitochondrial dysfunction - what are the possible inheritance modes?
A) maternal inheritance, autosomal recessive, dominant and X linked inheritance
B) maternal inheritance but not autosomal recessive, dominant and X linked inheritance
C) maternal inheritance but not autosomal recessive, dominant but not X linked inheritance

Answer 20

A - because both nuclear and mitochondrial origins for mitochondrial diseases/disorders

Question 21

Answer 21

B/C - mostly C

Question 22

Answer 22

B