Mitochondria

Question 1

What are the compartments of the mitochondria?

Answer 1

1. Outer membrane.
2. Inner membrane (Iamellar or tubular cristae).
3. Inner membrane space.
4. Matrix.

Question 2

What is the protein/lipid ratio of the outer membrane of the mitochondria?

Answer 2

1:1

Question 3

What are porins?

Answer 3

Porins are proteins that cross the mitochondrial membrane and act as pores. They are non-selective permeable.

Question 4

How are polypeptides transported across the outer membrane of the mitochondria?

Answer 4

Via translocons (TOMs)

Question 5

What’s the protein/lipid ratio in the inner membrane of the mitochondria?

Answer 5

4:1

Question 6

Which lipid contributes to about 20% of all lipid composition of the inner membrane of the mitochondria?

Answer 6

Cardiolipin

Question 7

How are polypeptides transported across the inner membrane of the mitochondria?

Answer 7

Via translocons (TIMs)

Question 8

How are molecules transported out and in of the mitochondria?

Answer 8

Multiple transport proteins (fully controlled transport).

Question 9

What does the matrix of the mitochondria contain?

Answer 9

1. mtDNA, mtRNAs, mt-ribosomes.
2. Krebs cycle enzymes.
3. Fatty acid beta-oxidation enzymes.
4. Calcium Phosphate deposits (dense bodies)

Question 10

Whats the main function of the mitochondria?

Answer 10

ATP production

Question 11

What are some functions of the mitochondria besides ATP production?

Answer 11

1. Beta-oxidation of short and medium-chain fatty acids.
2. Participation in steroid hormone synthesis.
3. Storage of calcium ions.
4. Involvement in apoptosis (in brown adipose tissue cells)
5. Generation of heat.

Question 12

What is so special with mitochondria compared to other cell organelles?

Answer 12

It possesses a complete genetic apparatus (ribosomes, DNA, mRNA, tRNA and enzymes nessesary.)

Question 13

How many rRNA molecules, tRNA molecules and Mitochondrial inner membrane proteins does the mitochondrial DNA encode for?

Answer 13

2 rRNA molecules

22 tRNA molecules

13 mitochondrial inner membrane proteins.

Question 14

What does it mean that the mitochondria are semiautonomous?

Answer 14

Some proteins are encoded and synthesized inside and by the mitochondria itself and some are synthesised in the nucleus of the cell and transported to the mitochondria. Hence semiautonomous.

Question 15

What have mitochondria evolved from according to the endosymbiotic theory?

Answer 15

Primitive bacteria capable of oxidative phosphorylation.

Question 16

What is the average size of mitochondria?

Answer 16

1-3 micrometers.

Question 17

What is the shape of mitochondria?

Answer 17

Mostly rod-shaped. Can also be spherical or highly elongated.

Question 18

What is present in the intermembrane of the mitochondria and what happens there?

Answer 18

1. Nucleotide kinases are present in the intermembrane of the mitochondria participating in ADP synthesis.
2. Acts as a contact site for translocon coupling. (Connecting the translocons of the outer and inner membrane)

Question 19

Does the inner membrane of the mitochondria contain the electron transport chain?

Answer 19

Yes.

Question 20

What does the production of ATP in the mitochondria require?

Answer 20

1. Citric acid enzymes
2. Electron transport chains
3. ATP synthase complexes.

Question 21

What is an electromotive force in the mitochondria?

Answer 21

The electron transport chain pumps protons from the matrix to the intermembrane space, creating a proton concentration gradient. The energy from this gradient is used by the ATP synthase complex to produce ATP. This proton gradient is called the electromotive force.

Question 22

What processes are the proton gradient across the mitochondrial membrane a source of energy for?

Answer 22

1. ATP synthesis
2. Active transport of molecules
3. Incorporation of proteins

Question 23

Does the DNA of mitochondria contain histones?

Answer 23

No. The DNA of mitochondria is arranged in a closed loop)