Mitochondria

Question 1

Where does electron transport take place?

Answer 1

In four large protein complexes embedded in the inner mitochondrial membrane.

Question 2

Which enzymes of metabolism are contained in the mitochondria?

Answer 2

1) Pyruvate dehydrogenase
2) TCA enzymes
3) Fatty acid oxidation enzymes
4) Electron transport/oxidative phosphorylation enzymes

Question 3

How much of eukaryotic cell volume do mitochondria take up?

Answer 3

20% (about 200 mitochondria per cell)

Question 4

What kind of membrane does mitochondria have?

Answer 4

Smooth outer membrane and extensively invaginated inner membrane.

Question 5

Where are electron transport and oxidative phosphorylation enzymes located?

Answer 5

They are bound to the inner mitochondrial membrane.

Question 6

What is the space in the mitochondria that is bound by the inner membrane and is comprised of a gel-like solution containing many metabolic enzymes (and other cofactors, genetic material, etc)?

Answer 6

Matrix (enclosed by inner membrane)

Question 7

What are the invaginated folds of mitochondria called?

Answer 7

Cristae

Question 8

What proteins located in the outer mitochondrial membrane allow free diffusion of molecules up to 10kD?

Answer 8

porins

Question 9

How much of the mass of the inner membrane of the mitochondria is comprised of proteins?

Answer 9

75%

Question 10

True or false: the mitochondria is richer in proteins than the cytosol.

Answer 10

True

Question 11

True or false: The intermembrane space of the mitochondria is richer in concentration of metabolites and ions than the cytosol.

Answer 11

False; porins in the outer membrane allow free diffusion of molecules up to 10 kD.

Question 12

Which molecules are allowed to freely travel across the inner mitochondrial membrane? How do other molecules move back and forth?

Answer 12

O2, CO2, H2O; all other molecules require transport proteins

Question 13

How do ATP, ADP, pyruvate, Ca2+, and phosphate get across the inner mitochondrial membrane?

Answer 13

Via transport proteins

Question 14

What results in the compartmentalization of metabolic functions between the cytosol and the inner mitochondria?

Answer 14

Controlled permeability (creating an ion gradient) of the inner membrane

Question 15

Which molecules are allowed to travel freely across the outer mitochondrial membrane?

Answer 15

Any up to 10 kD (via porins)

Question 16

Where in the mitochondria do most of the reactions of the citric acid cycle and fatty acid oxidation take place?

Answer 16

Mitochondrial matrix

Question 17

Where does oxidative phosphorylation take place?

Answer 17

Inner mitochondrial membrane

Question 18

What is the significance of the cristae (folds) of the mitochondial inner membrane?

Answer 18

It increases the surface area of the mitochondria, creating more sites for oxidative phosphorylation.

Question 19

True or false: The inner mitochondrial membrane is impermeable to almost all ions and polar molecules (they cannot simply diffuse).

Answer 19

True

Question 20

What is the membrane potential on the cytoplasmic side of the mitochondrial inner membrane?

Answer 20

positive

Question 21

What is the membrane potential on the matrix side of the mitochondrial inner membrane?

Answer 21

negative

Question 22

What kind of ion gradient is created by the selective permeability of the inner mitochondrial membrane?

Answer 22

Proton gradient