12 – Mitochondria II

Question 1

Mitochondria have their own

Answer 1

genome – present in multiple copies

Question 2

mitochondrial genomes encodes…

Answer 2

Genome encodes some of proteins of mitochondrial electron transport chain

Question 3

proteins – made in
Other components – made in

Answer 3

proteins – made in mitochondria
Other components – made in cytoplasm – imported to mitochondria

Question 4

Rest of mitochondrial genome – codes for

Answer 4

components of mitochondrial ribosomes & tRNAs needed – to make proteins encoded in mitochondrial genome & made in situ

Question 5

In humans & C.elegans nematode round worms

Answer 5

mitochondria in zygote originate from oocyte
-Not sperm

Question 6

Phenotypes produced by mitochondrial mutation show maternal/paternal inheritance

Answer 6

maternal

Question 7

Mitochondria can be

Answer 7

Homoplasmic – all copies are same
Heteroplasmic – 2 or multiple types of copies

Question 8

Degree of heteroplasmy can change by…2

Answer 8

1. by selection for/against a mutant copy due to structure of DNA
   -Small copies might be favored
2. by selection due to an advantage for cells that carry more copies of a mutant type

Question 9

example of selection due to an advantage for cells that carry more copies of a mutant type

Answer 9

Mutant mitochondrial DNA carrying a mutation in protein cytochrome b capable of partially suppressing deleterious embryonic slow development phenotype of long-lived isp-1 mutants in C.elegans

Question 10

Differences in degree of heteroplasmy in different individuals

Answer 10

Responsible for difference in phenotype between individuals carrying same mutant mitochondrial DNA
-Might be due to differences in nuclear genomes
-codes for most of mitochondrial proteins & how mitochondria interact with rest of the cell

Question 11

protein involved in fission

Answer 11

DRP1

Question 12

Degree of fragmentation - linked to

Answer 12

functional state
-Fragmented mitochondria = stressed/low ATP production
-Fused mitochondria = unstressed/high ATP production

Question 13

fission & fusion accumulate damage to their ..

Answer 13

DNA & protein contents

Question 14

ROS – reactive oxygen species =

Answer 14

by-product of metabolism
signaling molecules

Question 15

NADPH Oxidase (NOX) make

Answer 15

superoxide and/or hydrogen peroxide on purpose

Question 16

how do cell get rid of damaged mitochondria

Answer 16

Removal by mitophagy – type of autophage
-Clear out dysfunctional mitochondria & controls mitochondria #

Question 17

Fission & fusion enable

Answer 17

mitochondrial rescue and/or remove damaged mitochondria

Question 18

Fission – promotes

Answer 18

equal segregation of mitochondria into daughter cells

Question 19

Mitochondria make contact with

Answer 19

ER
-Calcium homeostasis
Export of mitochondria-synthesized molecules (ex.CoQ)
-In contact in a dynamic matter

Question 20

Fission occurs…

Answer 20

At point of ER-mitochondrial contact

Question 21

Three-parent babies

Answer 21

In-vitro fertilization to avoid transmission of mitochondria with defective DNA

Question 22

Dysfunctional mitochondria

Answer 22

Do not produce uniform disease manifestations
Different morphologies – different function & location

Question 23

process of dysfunctional mitochondria
-homoplasmy & heteroplasty

Answer 23

1. Homoplasmy – wild-type (unaffected)
2. Heteroplasmy – mutant mtDNA
3. Stable heteroplasmy
4. Drift – multiply one type of mtDNA
5. Drift to mutant homoplasmy – all mutant mtDNA