Test I: Citric Cycle and ETC

Question 1

Glycolysis

Answer 1

Anaerobic;
4 ATP produced during enzymatic reactions in the cytosol
2 ATP used to initiate glycolysis
2 ATP net gain to cell

Question 2

The Electron Transport System

and Citric Acid Cycle

Answer 2

Aerobic;
4 ATP from NADH produced in glycolysis;
24 ATP from NADH generated in citric acid cycle;
4 ATP from FADH2 generated in citric acid cycle
2 ATP via GTP produced during enzymatic reactions
36 net gain to cell from complete catabolism of one glucose molecule

Question 3

Mitochondrial ATP Production

Answer 3

1. If oxygen supplies are adequate, mitochondria absorb and break down pyruvic acid molecules
2. • H atoms of pyruvic acid are removed by coenzymes and are primary source of energy gain
3. decarboxylation

Question 4

decarboxylation

Answer 4

Process by which C and O atoms are removed and released as CO2

Question 5

Function of Citric Acid Cycle

Answer 5

To remove hydrogen atoms from organic molecules and transfer them to coenzymes

Question 6

Where does the citric acid cycle takes place

Answer 6

mitochondria

Question 7

Process of the citric acid cycle

Answer 7

• Pyruvic acid reacts with NAD and coenzyme A (CoA) = 1 CO2, 1 NADH, 1 acetyl-CoA
•Acetyl group transfers from acetyl-CoA to oxaloacetic acid producing citric acid
• CoA is released to bind another acetyl group
• One citric acid cycle removes two carbon atoms regenerating 4-carbon chain
• Several steps involve more than one reaction or
enzyme
• H2O molecules are tied up in two steps

Question 8

Waste product of citric acid cycle

Answer 8

CO2

Question 9

Products of citric acid cycle

Answer 9

NADH, FADH2, GTP, CoA, CO2

Question 10

Oxidative Phosphorylation

Answer 10

Is the generation of ATP
• Within mitochondria
• In a reaction requiring coenzymes and oxygen
• Produces more than 90% of ATP used by body
• Results in 2 H2 + O2 → 2 H2O

Question 11

Electron Transport System (ETS)

Answer 11

• Is the key reaction in oxidative phosphorylation
• Is in inner mitochondrial membrane
• Electrons carry chemical energy, transfer to oxygen, then H2O is formed
• Within a series of integral and peripheral proteins
• Energy released synthesizes ATP from ADP

Question 12

Functions of coenzymes

Answer 12

• Play key role in oxidation–reduction reactions
• Act as intermediaries
• Accept electrons from one molecule
• Transfer them to another molecule
• Gains energy

Question 13

What are the coenzymes in citric acid cycles and what do they do?

Answer 13

NAD and FAD

• Remove hydrogen atoms from organic substrates

Question 14

Coenzyme FAD

Answer 14

• Accepts two hydrogen atoms from citric acid cycle

* Gaining two electrons

Question 15

• Coenzyme NAD

Answer 15

• Accepts two hydrogen atoms
• Gains two electrons
• Releases one proton
• Forms NADH + H+

Question 16

Other name of ETS

Answer 16

respiratory chain

Question 17

Pigment complex of ETS

Answer 17

Contains a metal ion (iron or copper)

Question 18

Steps in Oxidative Phosphorylation

Answer 18

1. A coenzyme strips 2 hydrogen atoms from a substrate molecule. (NAD -> NADH)
2. NADH and FADH2 deliver hydrogen atoms to coenzymes embedded in the inner membrane of a mitochondrion. (NADH -> FMN; FADH2 -> CoQ)
3. Coenzyme Q releases hydrogen ions and passes electrons to cytochrome b.
4. Electrons are passed along the Electron Transport System, losing energy in a series of small steps.
5. Oxygen accepts the low-energy electrons, and with hydrogen ions, forms water.

Question 19

Where does glycolysis occur?

Answer 19

cytoplasm

Question 20

NAD and ATP Generation

Answer 20

• Energy of one electron pair removed from substrate in
citric acid cycle by NAD
• Pumps six hydrogen ions into intermembrane space
• Reentry into matrix generates three molecules of ATP

Question 21

FAD and ATP Generation

Answer 21

• Energy of one electron pair removed from substrate in
citric acid cycle by FAD
• Pumps four hydrogen ions into intermembrane space
• Reentry into matrix generates two molecules of ATP

Question 22

Summary of glycolysis

Answer 22

• Begins with glucose
• Ends with carbon dioxide and water
• Is main method of generating ATP

Question 23

Summary of Citric Acid Cycle

Answer 23

• Breaks down 2 pyruvic acid molecules
• Produces 2 ATP by way of GTP
• Transfers H atoms to NADH and FADH2
• Coenzymes provide electrons to ETS

Question 24

Summary of ETS

Answer 24

• Each of eight NADH molecules, Produces 3 ATP + 1 water molecule
• Each of two FADH2 molecules Produces 2 ATP + 1 water molecule
• Total yield from citric acid cycle to ETS = 28 ATP

Question 25

Output of glycolysis

Answer 25

2 x NADH, 2 x ATP, 2 x Pyruvate

Question 26

Key steps of glycolysis with enzymes

Answer 26

I. The hexokinase (HK): converts Glucose to G6P
II. The phoshofructokinase (PFK): converts F6P to F1, 6BP
III. The Phosphoglycerate kinase (PGK): converts 1,3BPG to 3PG
IV. The pyruvate kinase: converts PEP to pyruvate