mitochondria

Question 1

What role does electrons play in oxidative phosphorylation?

Answer 1

it gives the complexes energy to pump protons from the matrix to the intermembrane space to create a proton gradient

Question 2

Which are the complexes and enzymes involved in the ETC? What do each of the complexes do?

Answer 2

I: pumps protons into intermembrane space
II: converts succinate to fumarate
Coenzyme Q: brings e- from complex I and II to III
III: pumps protons into intermembrane space
cytochrome c: electron carrier from II to III
IV: pumps protons into intermembrane space

Question 3

what is complex V?

Answer 3

ATP synthase

Question 4

how is mtDNA involved in OXPHOS

Answer 4

mtDNA is encoded in OXPHOS complex subunits, except complex II
(eg ND1, ND2, ND4, ND4L, ND5, ND6)

Question 5

Does mtDNA have proofreading ability? Implications?

Answer 5

mutations are accumulated over time, diff people got diff mito mutations -> lead to mito diseases

Question 6

describe the mtDNA

Answer 6

double stranded, circular DNA
inner strand: light strand
outer strand: heavy strand
has a single promoter, genes are regulated by its specific methylation

Question 7

What does mtDNMT1 stand for and what does it do? What is it regulated by?

Answer 7

mitochondria DNA methyltransferase 1
- first discovered and most common methyl transferase
- mtDNMT1 expression is regulated by factors that respond to oxidative stress
- can initiate and maintain cytosine methylation in mito

Question 8

what is the D-loop?

Answer 8

a non-coding region that acts as a promoter for both the heavy and light strands of the mtDNA, and contains essential transcription and replication elements
regulates the replication and transcription of mtDNA

Question 9

where of mtDNA is methylated?

Answer 9

CpG, CpA, CpC, CpT

Question 10

How does the mt and nucleus interact?

Answer 10

non coding mtRNA can affect/alter gene/protein expression of nDNA, which can help to express mtDNA differently
non coding nDNA can also alter the expression of mtDNA

Question 11

what is Tfam?

Answer 11

mitochondrial transcription factor A
it is a DNA binding protein involved in organisation of mt genome (ie mtDNA compaction)
involved in post translational modifications: acetylation, phosphorylation, ubiquitination

Question 12

non coding regions of mitochondrial DNA - %, encoded by which strand, what it does?

Answer 12

7% ncDNA, majority encoded by L strand
most mt ncDNA regulates sense coding regions