Glycolysis

Question 1

what are the products of glycolysis?

Answer 1

ATP, NADH, and pyruvate

Question 2

what are the products of the pentose phosphate pathway?

Answer 2

NADPH and ribose sugars

Question 3

what is the product of the pyruvate dehydrogenase complex?

Answer 3

Acetyl CoA

Question 4

what are the products of the citric acid cycle?

Answer 4

NADH, FADH2, and ATP

Question 5

what is the product of oxidative phosphorylation?

Answer 5

ATP

Question 6

what is cellular respiration?

Answer 6

the cellular pathways that synthesize ATP by moving electrons from glucose (or other carbons) to oxygen

Question 7

what are the 3 stages of cellular respiration?

Answer 7

1. glycolysis and acetyl coa production (anaerobic)
2. citric acid cycle aka kreb’s cycle (aerobic)
3. oxidative phosphorylation aka electron transport chain (aerobic)

requires oxygen as an electron acceptor

gives off CO2

Question 8

T or F:

cellular respiration provides the pathway for precursor synthesis of amino acids, lipids, nucleic acids, and small molecules

Answer 8

true

Question 9

how does glycolysis initiate glucose electron transfer?

Answer 9

it oxidizes carbons and reduces electron carriers

Question 10

what is the electron acceptor of glycolysis?

Answer 10

NAD+, which must be maintained

Question 11

is glycolysis aerobic or anaerobic?

Answer 11

it is anaerobic; occurs in the absence of oxygen

Question 12

there are 2 stages of glycolysis. what are they?

Answer 12

1. preparatory stage - phosphorylation
2. payoff stage - oxidation-reduction

Question 13

glycolysis is the primary/unique source of energy for which cell types?

Answer 13

• erythrocytes (lack mitochondria)
• cancer cells
• anaerobic bacteria

Question 14

describe the steps of the preparatory phase of glycolysis

Answer 14

phosphorylation of glucose and its conversion to glyceraldehyde 3-phosphate

Question 15

describe the steps of the payoff phase of glycolysis. what is the net balance?

Answer 15

• oxidative conversion of glyceraldehyde 3-phosphate to pyruvate and the coupled formation of ATP and NADH
• net balance is 2 pyruvate, 2 ATP, and 2 NADH + H+

Question 16

what occurs in the pentose phosphate pathway?

Answer 16

• glucose 6-phosphate can be diverted to the pentose phosphate pathway (as opposed to glycolysis or gluconeogenesis)
• synthesizes key cell components: NADPH (electron donor), ribose sugars (nucleotides, ATP, FAD, and coenzyme A), NAD+ and NADP+ (electron acceptors)

Question 17

NADPH is a product of the pentose phosphate pathway. why is it important?

Answer 17

it is necessary for reductive biosynthesis (creating FAs) and free radical protection, and must be maintained within the cell

Question 18

describe how the pentose phosphate pathway is regulated

Answer 18

excessive amounts of NADPH will inhibit this process and shunt the glucose 6-phosphate to the glycolysis pathway

Question 19

once pyruvate is produced, it has two fates. what are they?

Answer 19

1. under aerobic conditions, it can be converted to coenzyme A and feed into the citric acid cycle
2. under hypoxic/anaerobic conditions, it can be converted to lactic acid via fermentation

Question 20

describe fermentation

Answer 20

• the regeneration of NAD+ in anaerobic conditions, which allows glycolysis to continue
• NAD+ must be regenerated for glycolysis to work, because NAD+ is its electron acceptor
• lactate is the electron acceptor of NADH produced in glycolysis
• lactate is readily transported out of cells and into the blood (cori cycle)
• lactate is the substrate for liver gluconeogenesis (cori cycle)

Question 21

how is NAD+ regenerated in fermentation?

Answer 21

• lactate is formed from pyruvate via lactate dehydrogenase, which converts NADH + H+ to NAD+