4:3a Respiration

Question 1

Define cellular respiration

Answer 1

It is the process by which glucose is oxidized to produce ATP (energy)

Question 2

What is the general process of cellular respiration in words?

Answer 2

1: Macromolecules such as starch are broken down through enzymatic hydrolysis which may occur in organs or specialized organelles like the lysosome.
2: glucose is converted into two three-carbon molecules (pyruvate) in the cytosol. A small amount of energy is released.
3: this takes place entirely in the mitochondria and produces large amount of energy (ATP)

Question 3

What is the equation of aerobic respiration in cellular respiration?

Answer 3

C6H12O6 + 6O2 = 6CO2 + 6H2O + energy

Question 4

Where is energy released from cellular respiration used?

Answer 4

Half of the energy released from cellular respiration is used to drive the formation of adenosine triphosphate from inorganic phosphate and ADP.

The other half is released as body heat.

Question 5

What is the reduced form of NAD+ (oxidized form)

Answer 5

NADH

Question 6

What are the 3 stages of aerobic respiration?

Answer 6

Glycolysis
Krebs cycle
Oxidative phosphorylation

Question 7

Where does glycolysis (cellular respiration) take place?

Answer 7

Cytosol

Question 8

Where does pyruvate oxidation (after glycolysis) take place?

Answer 8

Mitochondrial matrix/ mitochondrion

Question 9

Describe glycolysis (cellular respiration)

Answer 9

• occurs in cytosol
• sequence of 10 enzyme catalyzed reactions
• each molecule of glucose converted to 2 molecules of pyruvate
• ATP produced without oxygen

For 1 molecule of glucose, 2 molecules of ATO are hydrolysis to provide energy to drive the process, leading to the production of 2 molecules of pyruvate and 4 molecules of ATP

2NAD+ is also reduced into 2NADH which also produces 2H+ ions

2 net molecules of ATP

Question 10

What happens between glycolysis and pyruvate oxidation?

Answer 10

Pyruvate is transported from the cytosol across the mitochondrial membrane to the matrix through a transport protein.

Question 11

Describe link reaction (pyruvate oxidation)

Answer 11

Pyruvate is oxidized, losing an electron to NAD+ which forms NADH and released a H+. It then attaches to coenzyme A to form acetyl-CoA, which is used in the Krebs cycle.

This happens in the mitochondrial matrix

Question 12

Describe the Krebs cycle (Citric acid cycle)

Answer 12

• occurs in the mitochondrial matrix
• does not need oxygen, but needs the presence of oxygen.

It completely oxidizes carbon atoms of the acetyl group in acetyl- CoA to form carbon dioxide.

For 1 acetyl-CoA entering the cycle, two molecules of CO2 are produced. Energy released by the oxidation is store in 3 NADH, 1 GTO and 1 FADH2.

Question 13

Describe oxidative phosphorylation

Answer 13

Electrons are transferred from NADH and FADH2 to oxygen (final electron acceptor) through membrane proteins in the electron transport chain. This regenerates NAD+ and FAD

As electrons are transferred, protons go into the inter membrane space, creating a proton gradient.

Then during chemiosmosis, Protons flow back down the gradient through ATP synthase. This phosphorylates ADP and an inorganic phosphate group into ATP.

Question 14

What is Q/first round protein thing in electron transport chain

Answer 14

Quinone

Question 15

What 2 purposes does the electron transport chain serve?

Answer 15

1: establishing a proton gradient for the bulk of ATP synthesis
2: regenerates NAD+ and FAD to allow continuity of earlier stages

Question 16

What is Cyt C/ second round protein thing in electron transport chain

Answer 16

Cytochrome c

Question 17

When and where does anaerobic respiration occur in humans?

Answer 17

It occurs in muscles during strenuous exercise when sufficient oxygen is not available

Question 18

Describe anaerobic respiration

Answer 18

It occurs when oxygen supply is inadequate or absent. Glycolysis can still occur though, and produce small amounts of ATP.

Condition: there has to be a constant supply of NAD+. In anaerobic, it is regenerates by converting pyruvate into products excreted from the cell instead of for the krebs cycle.

The collective process of glycolysis and regeneration of NAD+ is known is fermentation.

Question 19

What are the two forms of fermentation?

Answer 19

Alcohol fermentation and lactate fermentation.

Question 20

Describe alcohol fermentation (in yeast)

Answer 20

2 Pyruvate will be converted to 2 acetaldehyde, releasing 2 CO2. The 2 acetaldehyde is reduced to ethanol by NADH, regenerating NAD+ for glycolysis to continue

Question 21

Describe lactate fermentation (in muscle cells)

Answer 21

It involves conversion of pyruvate into lactate. It occurs in muscles during intense exercise. The reduction regenerates NAD+, which is used in glycolysis. No CO2 is produced.