Mitochondria

Question 1

Where are mitochondrial genes encoded?

Answer 1

In the nucleus and from the mitochondria

Question 2

What are the attributes of the mitochondrial genome?

Answer 2

Small and circular; consists of noncoding DNA, tRNA genes, protein-coding genes (NADH dehydrogenase subunits or ATP synthase genes), and rRNA genes

Question 3

Where is the gene for mt ribosomes located in the cell?

Answer 3

In the nuclear genome

Question 4

What tissues are most affected by mt defects?

Answer 4

Organs and tissues that have high energy demands

Question 5

What mechanism accounts for how mt are inherited?

Answer 5

Random segregation at cytokinesis

Question 6

T/F: The shape of a mt is standard and rigid because it needs a certain configuration to produce ATP

Answer 6

False; mitochondria take many shapes in order to meet the needs of the cell

Question 7

How do mt move around the cell?

Answer 7

Adaptor protein (Miro) is embedded in the outer membrane of the mt and attaches to motor protein (Cenp-F)

Question 8

Random segregation of the cytoplasm contributes to what evolutionary effect?

Answer 8

Bottleneck effect

Question 9

What is a 3 parent embryo?

Answer 9

Embryo that has the nucleus of an original couple, but this nucleus has been placed in the cytoplasm of a 3rd-party donor egg cell

Question 10

How might the presence of mitochondria vary in flagellar cells versus secretory cells?

Answer 10

Flagellar cells have mitochondria tightly wrapped around the flagella, and organelle that has a high energy demand. Secretory cells are likely to have energy needs in multiple places resulting in the mitochondria being more spread out.

Question 11

What is the consequence of mitochondria being distant from an ATP sink?

Answer 11

Function fluctuates depending on where mt is located, decreased function when mt is not present. Consistent functions requires consistent mt access.

Question 12

What makes neuronal cells good for studying mt movement?

Answer 12

Neurons have long axons where not all of the cell machinery is present. Thus, they have evolved to have an efficient transport system. (i.e. the machinery to break down damaged mitochondria is only present in the cell body, not the axon)

Question 13

Elevated calcium

Answer 13

Elevated ATP production

Question 14

How is mitochondrial health maintained?

Answer 14

Fission and fusion of mitochondria; damaged mt can be fused together and fissioned off to be broken down (protects the rest of the mt)

Question 15

Mitochondrial fission protein

Answer 15

Drp1 (similar to dynamin)

Question 16

Mitochondrial fusion protein

Answer 16

Opa1 (inner membrane) and Mitofusin (outer membrane)

Question 17

Why is there 1 protein dedicated to mt fission, but 2 for mt fusion?

Answer 17

The 2 for mt fusion account for the 2 mt membranes, however, 1 fission protein is enough to pinch both membranes

Question 18

Which requires more GTP, fusing the inner membrane or the outer membrane?

Answer 18

Inner membrane

Question 19

Defected Drp1

Answer 19

1 large mitochondria

Question 20

Defected Opa1

Answer 20

Large outer membrane with small inner membranes