mitochondria

Question 1

mitochondria

Answer 1

• Double Membrane
  o Inner Membrane folded many
  times to incr. SA
   Generate most of the ATP in cells
   Inner most space is called the Matrix
   Contain their own DNA
   Generally inherited maternally

Question 2

Mitochondrial genes

Answer 2

The human mitochondrion contains 5–10 identical, circular molecules of DNA.

Question 3

mutations in mtDNA cause human diseases

Answer 3

• Mutations in 12 of the 13 polypeptide-encoding mitochondrial genes have been found to cause human disease.
• disorders of the muscles and brain are the most common. Perhaps this reflects the great demand for energy of both these organs. (Although representing only ~2% of our body weight, the brain consumes ~20% of the energy produced when we are at rest.)
• Some of these disorders are inherited in the germ-line. The mutant gene is received from the mother because none of the mitochondria in sperm survives in the fertilized egg.
• Other disorders are somatic; that is, the mutation occurs in the somatic tissues of the individual.

Question 4

Example of mutation
- exercise intolerance

Answer 4

• A number of humans who suffer from easily-fatigued muscles turn out to have mutations in the cytochrome b gene.
• Only the mitochondria in their muscles have the mutation; the mtDNA of their other tissues is normal. Presumably, very early in their embryonic development, a mutation occurred in a cytochrome b gene in the mitochondrion of a cell destined to produce their muscles.

Question 5

What is the mixing of mutant and normal DNA Called

Answer 5

heteroplasmy.

Question 6

What is is it Called with the mitochondria carries all mutant genomes

Answer 6

homoplasmy (a phenomenon resembling genetic drift).

Question 7

Why do mitochondria have their own genome?

Answer 7

Simply put, to allow redox regulation of gene expression**

• Many of the features of the mitochondrial genetic system resemble those found in bacteria, strengthening the theory that mitochondria are the evolutionary descendants of a bacterium))
• However, many of the genes needed for mitochondrial function have since moved to the nuclear genome.

-The recent sequencing of the complete genome of Rickettsia prowazekii has revealed a number of genes closely related to those found in mitochondria through oxidative level phosphorylation. As they produce ATP in the same way and lack genes to produce it through glycolysis