Mitochondria, Metabolism, and Energy

Question 1

Mitochondria are dynamic

Answer 1

Often exist as interconnected structures that fuse and divide through catalysis by free radicals.
Mitochondrial fission.

Question 2

Mitochondrial fission

Answer 2

Endoplasmic reticulum encircles the mitochondria, recruiting Drp1.
Drp1 forms a helix around the mitochondrion.
GTP hydrolysis by Drp1 leads to a conformational change, splitting the mitochondrion.

Question 3

Drp1

Answer 3

A monomeric G protein, or a GTPase.

Question 4

Cristae junctions

Answer 4

Beginning of the folds that form the cristae.

Question 5

OMM porins function

Answer 5

Permit moderately sized molecules to move from the cytoskeleton to the intermembrane space.

Question 6

Porins unique characteristics

Answer 6

Integral proteins that are made up of beta-sheets.

Question 7

IMM protein to lipid ratio

Answer 7

3:1 proteins to lipids

Question 8

F1 particles

Answer 8

8.5nm

Question 9

Cardiolipin

Answer 9

unusual lipid in the inner membrane with a double phospholipid -> 4 fatty acid chains. Acts to insulate the membrane.
Diphosphatidylglycerol.

Question 10

Why does the matrix contain ribosomes and circular DNA

Answer 10

Endosymbiont theory, engulfed ancient purple prokaryotes (small, aerobic) about 1.25 bya.

Question 11

Catabolic vs anabolic metabolic pathways

Answer 11

Disassembly of complex molecules - releases energy (breakdown of glucose to pyruvate).
Synthesis of more complex compounds - consumes energy (amino acids joining by condensation reactions).

Question 12

Energy of the hydrolysis of ATP

Answer 12

ΔG = -30 kJ/mol

Question 13

4 features of the mitochondria explained by the endosymbiont theory

Answer 13

Comparable size to prokaryotes, ribosomes, circular mtDNA, double membrane system.

Question 14

Redox reactions of cellular respiration

Answer 14

Transfer of electrons (H atoms) from one compound to another. Remove e- = oxidation, gain e- = reduction. always coupled to increase energetic favourability.

Question 15

Substrate level phosphorylation

Answer 15

Direct interaction of substrate and enzyme to create the product using ATP

Question 16

Oxidation of glucose

Answer 16

Results in the reduction of NAD+

Question 17

NAD+

Answer 17

Nicotinamide adenine dinucleotide
A non-protein cofactor (coenzyme) that carries two electrons and one hydrogen.

Question 18

3 phases of glycolysis

Answer 18

Preparation and cleavage, 2 ATP used.
Oxidation of sugar and 2 ATP generation.
Pyruvate formation and 2 ATP generation

Question 19

Inputs and outputs of glycolysis

Answer 19

1 glucose, 2 NAD+ and 2 ADP/Pi.
2 Pyruvate, 2 NADH, 2 ATP, 2 H+ and 2 H2O.

Question 20

Pyruvate dehydrogenase location/function

Answer 20

Located in the mitochondrial matrix, catalyses the oxidation of pyruvate.

Question 21

Oxidation of pyruvate

Answer 21

NAD+ acts as an oxidising agent, and Coenzyme A incorporates to produce Acetyl CoA and CO2.

Question 22

Basic steps of the citric acid cycle

Answer 22

Occurs in the matrix of the mitochondria.
CoA group leaves. Acetyl group attaches the oxaloacetate to make citrate. Two CO2 molecules removed, 3 NADH produced, one FADH2 produced. ATP/GTP made. oxaloacetate regenerated.

Question 23

Citric acid cycle outputs

Answer 23

Acetyl CoA, 3 NAD+, ADP+Pi, 1 FAD

Question 24

FADH2

Answer 24

Flavin adenine dinucleotide. Carries 2 electrons and 2 hydrogens, with slightly less energy than the e- carried by NADH.

Question 25

Enzyme 6 of the CaC is in the ETC

Answer 25

Succinct dehydrogenase of complex II in the ETC, produces FADH2 in the citric acid cycle.

Question 26

Oxidative phosphorylation

Answer 26

The production of ATP using energy of redox reactions in the ETC. Oxygen is the final electron recipient, and therefore must be present.

Question 27

Electron transport chain components

Answer 27

Four complexes, coenzyme Q, cytochrome C. Each complex has an INCREASING reduction potential.

Question 28

Reduction potential through the ETC

Answer 28

Ability to acquire electrons increases down the chain, releasing energy each time.

Question 29

Cytochrome C

Answer 29

Irving Geis. Responsible for energy transfer from complex III to complex IV.

Question 30

Coenzyme Q (ubiquinone)

Answer 30

Fat -soluble molecule that resembles vitamin K. passes energy from complex I to complex III.

Question 31

For one NADH, — H+ are pumped

Answer 31

10 H+

Question 32

Separation of transfers in the ETC

Answer 32

To maximise energy captured, there is only one path electrons may follow through the ETC.

Question 33

One FADH2 transfers — H+, through complex ___

Answer 33

6 H+, complex II (succinate dehydrogenase)

Question 34

Electron transport chain is a target for many poisons

Answer 34

Azide, cyanide, carbon monoxide.

Question 35

Chemiosmotic theory (Peter Mitchell)

Answer 35

The H+ gradient provides the potential energy to phosphorylation ADP - synthesising ATP. Proton gradient is both a difference in pH and charge.

Question 36

ATP synthase F1 components

Answer 36

8.5 nm, α3, β3, γ, δ, ε.

Question 37

ATP synthase F0 components

Answer 37

a, b2, c10-14

Question 38

F1 structure

Answer 38

Mobile - one γ subunit, one ε unit. Static - one δ and a ring of α3β3 subunits

Question 39

F0 structure

Answer 39

In the matrix. Static - one a subunit and two b subunits. Mobile - Ten c subunits.

Question 40

Binding change mechanism (Paul Boyer)

Answer 40

Nobel prize (1997) Three β catalytic sites around γ bind ADP and Pi in a sequence ( to undergo a conformation change as to make a tightly bound ATP, then change again to release the ATP.

Question 41

Ionophores

Answer 41

Allow proteins to leak across the membrane and bypass ATP synthase - uncouplers.

Question 42

2,4-dinitrophenol

Answer 42

an ionophore that can protonate/deprotonate to pass back and forth through the membrane.

Question 43

Natural uncoupling proteins

Answer 43

UPCs found in brown fat tissue to use more heat.

Question 44

Fermentation

Answer 44

Allows for sustained generation of ATP via glycolysis whilst regenerating NAD+.