Cellular Respiration

Question 1

What is cellular respiration

Answer 1

Production of energy by breaking down glucose

Question 2

4 stages of cellular respiration

Answer 2

1. Glycolysis
2. Pyruvate oxidation
3. Citric acid cycle
4. Oxidative phosphorylation

Question 3

Glycolysis

C6H12O6+6O2–>6CO2+6H2O+energy

Answer 3

• cytosol
• anaerobic
• glucose is converted into more usable form=Pyruvate
• 2net ATP & 2NADH

Question 4

Pyruvate oxidation

Answer 4

• Pyruvate moves into mitochondrion using transport protein
• Pyruvate releases CO2 & forms acetate
• acetate joins with CoA to form acetyl-CoA

🔺NB: in the absence of oxygen fermentation takes place where NADH becomes NAD+ as H+ is recycled. Lactic acid is produced and glycolysis continues

Question 5

Citric acid cycle

Answer 5

• mitochondrion
• aerobic
• must occur twice per 1 glucose molecule

—>2ATP;2FADH2;6NADH

Question 6

Oxidative phosphorylation

Answer 6

1. electron transport

2. Chemiosmosis

Question 7

Electron transport

Answer 7

H

Question 8

Regulation of cellular respiration

Answer 8

**allosteric enzymes at certain points in respiratory pathway respond to inhibitors & stimulators which ensure regulation of citric cycle and glycolysis.

AMP stimulates phosphofructokinase
ATP inhibits phosphofructokinase
Citrate inhibits phosphofructokinase

***phosphofructokinase is in between glycolysis and Pyruvate.

Question 9

Chemiosmosis

Answer 9

Yoh

Question 10

Exergonic & Endergonic reactions

Answer 10

•Exergonic:*exothermic
Catabolic 
Releases energy
Spontaneous 
Energetically favorable 

•Endergonic:*endothermic
Anabolic
Absorbs energy 
Non spontaneous 
Energeticically unfavorable

Question 11

How do enzymes lower the required energy of activation for a reaction?

Answer 11

Enzymes speed up metabolic rate by lowering energy barriers

Activation energy: energy needed to break bonds and allow reaction to occur

*bond breaking requires energy
*bonds forming release energy
_____________________________________________

• enzymes can act as template for substrate orientation
• stressing substrate & stabilizing transition state
• provide favorable micro environment
• participate directly in catalytic reaction

How:

1. Substrate enters active site
2. Substrate=held in active site by weak interactions
3. Active site decreases activation energy and speeds up reaction
4. Substrate is converted into product
5. Products are released
6. Active site available for new substrate molecules

Question 12

Heat can increase activation energy but why is it not used?

Answer 12

• heat denatured proteins and kills cells
• heat would speed up all the reactions and not only the required ones.

***enzymes can only speed up reactions that were gonna occur

🔺G is unaffected by enzymes