Respiration

Question 1

Aerobic vs. anaerobic

Answer 1

aerobic: 36-38 ATP per glucose (32 from glucose alone), oxygen final electron acceptor, substrate-level and oxidative phosphorylation
anaerobic: 2-36 ATP, NO3, SO42-, CO32- and endogenous molecules final electron acceptors, substrate level and oxidative
fermentation: 2 ATP, substrative level, endogenous molecules final electron acceptors, only partial degradation of sugar

Question 2

in cell respiration, what is oxidized and reduced?

Answer 2

CO2 is oxidized, glucose is the reducing agent
Oxygen is oxidizing agent, and water is reduced

Question 3

Nicotinamide adenine dinucleotide

Answer 3

NAD+ coenzyme
With additional H on nicotinamide (and 2 e) it is NADH
adenosine + nucleotide nicotinamide, phosphates connected

Question 4

Energy investment phase glycolysis

Answer 4

1. Glucose + ATP –> Glucose-6-phosphate
2. Glucose-6-phosphate –> fructose-6-phosphate
3. Fructose-6-phosphate + ATP –> fructose-1,6-bisphosphate
4. Fructose-1,6-bisphosphate –> Glyceraldehyde-3-phosphate (G3P) and dihydroxyacetone phosphate (DHAP)
5. Dihydroxyacetone phosphate –> G3P

Question 5

Energy payoff phase glycolysis

Answer 5

6. Glyceraldehyde-3-phosphate –> 1,3-bisphosphoglycerate + NADH
7. 1,3-bisphosphoglycerate –> 3-phosphoglycerate + ATP
8. 3-phosphoglycerate –> 2-phosphoglycerate
9. 2-phosphoglycerate –> phosphoenolpyruvate + H2O
10. Phosphoenolpyruvate –> pyruvate + ATP

Question 6

Steps that produce ATP in glycolysis

Answer 6

1,3-bisphosphate –> 3-phosphoglycerate
phosphoenol pyruvate (PEP) –> pyruvate
2 per G3P (4 total)

Question 7

Steps that produce NADH in glycolysis

Answer 7

Glyceraldehyde-3-phosphate –> 1,3-bisphosphoglycerate

Question 8

Steps in glycolysis where ATP is consumed

Answer 8

Glucose –> glucose-6-phosphate
Fructose-6-phosphate –> fructose 1,6-bisphosphate

Question 9

G3P vs DHAP structure

Answer 9

alydehyde vs. ketone

Question 10

Pyruvate oxidation steps

Answer 10

1. CO2 released
2. 2-C molecule oxidized to acetate releasing NADH
3. Acetate linked to coenzyme A making acetyl-coA

Question 11

Which carbons are burned off as CO2 in citric acid cycle?
During which steps?

Answer 11

Carbons from acetyl coA (glucose)
Isocitrate –> alpha-ketoglutarate
Alphaketoglutarate –> succinyl coA

Question 12

First half of citric acid cycle

Answer 12

1. Acetyl coA + oxaloacetate –> citrate
2. Citrate –> isocitrate
3. Isocitrate –> alpha-ketoglutarate + NADH + CO2
4. Alpha-ketoglutarate + CoA –> succinyl coA + NADH + CO2

Question 13

Second half of citric acid cycle

Answer 13

5. Succinyl coA + GDP –> succinate + GTP
6. Succinate FAD –> fumarate + FADH2
7. Fumarate + H2O –> malate
8. Malate –> oxaloacetate + NADH

Question 14

Steps in CAC where NADH is produced
FADH?

Answer 14

3. Isocitrate –> alpha-ketoglutarate
4. Alpha-ketoglutarate –> succinyl coA
5. Malate –> oxaloacetate
6. Succinate –> fumarate (FADH2)

Question 15

When is ATP produced in CAC?

Answer 15

Succinyl coA –> succinate produces GTP which is then converted to ATP

Question 16

Location of ETC in mitochondria vs. chloroplasts

Answer 16

Mitochondria: ETC is in inner mitochondrial membrane, H+ are pumped into intermembrane space and flow back into mitochondrial space through chemiosmosis

Chloroplasts: ETC is in thylakoid membrane, H+ are pumped into thylakoid space and flow back into the stroma through chemiosmosis

Question 17

Electron transport chain pathway

Answer 17

NADH drops off e at complex I
FADH drops off e at complex II
Electrons flow to Q, complex III and then cytochrome c
And then to complex IV where O is present as final e acceptor

H+ pumped into intermembrane space at complex I, III and IV
Energy released from electron transport is used to fuel chemiosmosis
32 ATP produced

Question 18

ATP synthase

Answer 18

uses H+ flowing down electron gradient (potential energy) to phosphorylate ATP from ADP called the proton motive force

H+ enter stator and then add to rotor where they rotate and then flow back into mitochondrial matrix

Question 19

Fermentation, how does it make ATP? Overview

Answer 19

pairing glycolysis with fermentation, which regenerates NAD+
alcohol and lactic acid fermentation
2 ATP produced

Question 20

Alcohol fermentation mechanism

Answer 20

Pyruvate –> acetaldehyde –> ethanol
releases CO2 and regenerates NAD+ for glycolysis
wasteful, brewing, wine, and baking

Question 21

Lactic acid fermentation mechanism

Answer 21

Pyruvate –> lactic acid
regenerates NAD+ for glycolysis
fungi and bacteria (cheese, yogurt) and human muscle cells
lactate waste product, no CO2 released

Question 22

Obligate anaerobes use

Answer 22

fermentation and cannot live with O2 environment

Question 23

How does a facultative anaerobe work

Answer 23

pyruvate can lead to TCA or fermentation depending on O2 availability

Question 24

How can fats produce energy?

Answer 24

Glycerol –> glyceraldehyde-3-phosphate (glycolysis)
Fatty acids –> acetyl coA via beta oxidation

Question 25

How can proteins produce energy?

Answer 25

Amino acids –> pyruvate, acetyl coA or straight into CAC
NH3 eliminated as waste

Question 26

how much of 1 glucose molecule is utilized for energy

Answer 26

~34%, the rest is released as heat

Question 27

Feedback inhibition of cellular respiration

Answer 27

High AMP: stimulates glycolysis (ex. phosphofructokinase) (speeds up)
High ATP and high Citrate: inhibits glycolysis (slows down)