Mitochondria and Y-linked Inheritance

Question 1

Inheritance pattern of Y-linked trait

Answer 1

Transmission from male to male only

All males from affected males are affected

Question 2

Does the y chromosome show recombination?

Answer 2

Most doesn’t (non-combining region), but ends do

Question 3

Pseudoautosomal regions of y chromosome

Answer 3

Ends of y chromosome

Undergo recombination

Question 4

Mitochondrial trait inheritance pattern

Answer 4

Inheritance only through mother
Trait is passed on to every child (both male and female)
More affected per generation than recessive, dominant, or X-linked

Question 5

3 differences between mitochondrial and nuclear DNA

Answer 5

1. Mitochondria contains 100s to 1000s of copies of genome; nucleus contains 2
2. Can be varying proportion of mutant mtDNA molecules; 0, 1, or 2 mutant alleles in nuclear DNA
3. mtDNA is inherited maternally only; nuclear DNA is inherited from both parents

Question 6

3 functions of mitochondria

Answer 6

1. Production of energy (ATP)
2. Initiation of apoptosis
3. Generation of reactive oxygen species (causes aging through mutation of DNA)

Question 7

Threshold effect

Answer 7

Visible in mitochondrial traits
Gradual change in mitochondrial genotype can result in sudden/abrupt change in phenotype
As people age, mitochondrial diseases begin to manifest
Systems that use most ATP such as CNS will show disease conditions earlier than other systems such as kidney

Question 8

Replicative segregation

Answer 8

During mitosis, mtDNA is distributed randomly into daughter cells: genotype of daughter cells can shift to wild-type, mutant, or remain mixed

Question 9

Heteroplasmy

Answer 9

2 genetically different mtDNA is in a cell

Phenotype depends on distribution of mutant DNAs

Question 10

Lebers hereditary optic neuropathy

Answer 10

Mitochondrial disease
Caused by mutation in mtDNA gene LHON
Causes blindness: degeneration of ganglion layer of retina and optic nerve