Mitochondria

Question 1

Function of mitochondria

Answer 1

Oxidative phosphorylation (production of ATP through use of oxygen), Calcium sequestration, cell death, generate heat, organ-specific functions (urea cycle in the liver)

Question 2

Structure of mitchondria

Answer 2

Double lipid bilayer, innermembrane - convoluted structures - cristae, matrix (w/ ribosomes), outermembrane

Question 3

Inner membrane contains:

Answer 3

cristae, contains proteins for electron-transport, ATP synthase, transport proteins, but is impermeable to protein diffusion, because of large amounts of cardiolipin

Question 4

Matrix contains:

Answer 4

enzymes (TCA cycle), DNA, RNA, Ca++ granules, ribosomes

Question 5

Outer membrane contains:

Answer 5

Channel-forming protein (porin), is semipermiable, lipid synthesis enzymes

Question 6

Intermembrane space contains:

Answer 6

Enzymes that use ATP to phosphorylate nucleotides

Question 7

Staining of mitchondria

Answer 7

show up as striations, can use immunohistochemistry, enzyme histochemistry

Question 8

Oxidative phosphorylation definition

Answer 8

Oxidative because using oxygen as reactant to phosphorylate ADP to ATP

Question 9

Oxidative phosphorylation steps

Answer 9

1. Pyruvate/FAs are transported into mitochondria from glycolysis and converted to acetyl CoA
2. Acetyl CoA goes through the citric acid cycle in the matrix and produces NADH and CO2
3. NADH is converted to NAD+ and e-
4. e- move down electron transport chain the inner mitochondrial membrane with oxygen as the final e- acceptor becoming water, that simultaneously pushed H+ into the intermembrane space
5. H+ flowing down its electrochemical gradient drives the production of ADP to ATP by ATP synthase

Question 10

Electron transport chain

Answer 10

Electron passed between different complexes in inner membrane

Question 11

Which has higher pH: inner membrane space or matrix?

Answer 11

Matrix because electron transport chain pumps H+ out

Question 12

Why do brown fat cells produce heat?

Answer 12

They uncouple ATPase and use H+ for lipid metabolism to make heat

Question 13

Metabolite transport

Answer 13

Carrier proteins that need energy, symporters driven by pH gradient and antiporters driven by voltage gradient

Question 14

Proteins targeted for matrix

Answer 14

TOM and TIM23, cleavable presequence

Question 15

Proteins targeted for inner membrane

Answer 15

TOM and TIM23, cleavable presequence AND ‘stop transfer’ sequence

Question 16

Proteins targeted for intermembrane space

Answer 16

TOM and TIM23, cleavable presequence AND inner membrane peptidase cleavage sequence

Question 17

What do chaperones do for proteins destined for the mitochondria

Answer 17

Keeps polypeptide in unfolded position until it gets to its final location

Question 18

Proteins w/out presequence

Answer 18

Some proteins lack presequence, but instead have noncleavable signals such as b-barrel proteins (porins), metabolite carrier proteins

Question 19

SAM complex

Answer 19

Important for proteins that need to stay in the outermembrane, such as porins, that go through TOM first and then are folded and then goes through SAM and into membrane

Question 20

TIM22 complex

Answer 20

Important for proteins that stay in the innermembrane, but that DONT have a cleavable presequence, that go through TOM first and then are folded and then goes through TIM22 and into membrane

Question 21

Chaperones use what form of energy

Answer 21

ATP and electrochemical gradient

Question 22

OXA translocase

Answer 22

Used for proteins synthesized in the mitochondria, presequence is not cleaved and protein is destined for inner membrane

Question 23

Ways to die when no ATP

Answer 23

Necrosis, causes inflammation

Question 24

Ways to die when ATP is available

Answer 24

Apoptosis, no inflammation

Question 25

Calcium and mitochondria

Answer 25

Calcium can trigger cascade of proteins leading to apoptosis