Biochem Final Glycolysis

Question 1

each process in cellular respiration produces either

overview cellular respiration

Answer 1

ATP or electron carries (3 NADH and 2 FADH2)

Glycolysis: 1 6-carbon glucose broken into 2 pyruvate
Pyruvate processing: each pyruvate oxidized to form acetyl coA
Citric Acid Cycle: each acetyl coA is oxidized to form CO2
ETC and oxidative phosphorylation: electrons move down ETC and their energy is used to create proton gradient which is used to make ATP (32 ATP in the end)

Question 2

definition of cellular respiration

Answer 2

any set of reactions that use electrons from high energy molecules to make ATP

Question 3

where other macromolecules can enter cellular respiration in the absence of glucose

Answer 3

glycolysis: sugars or glycerol
pyruvate oxidation: amino acids converted to pyruvate
citric acid cycle: fatty acids and amino acids can be converted to acetyl coA
or amino acids can directly enter citric acid cycle

Question 4

in a basic sense how does fermentation and anaerobic respiration work?

Answer 4

electronegative molecules function kind of as the oxygen molecule electron acceptor in a more simplified anaerobic pathway

Question 5

4 major pathways of glucose utilization

Answer 5

synthesis of structural polymers - extracellular matrix and cell walls
storage synthesis - glycogen, starch, sucrose
ribose 5-phosphate - oxidation via pentose phosphate pathway
pyruvate - oxidation via glycolysis

Question 6

importance of the study of glycolysis for biochemistry

Answer 6

understanding roles of coenzymes (study of cancer), discovery of pivotal role of ATP, enzyme purification methods, inspo for next gen

Question 7

preparatory phase

Answer 7

requires 2 ATP
enzymes: hexokinase, phosphohexose isomerase, phospho-fructokinase 1, aldolase
produces 1 GAP and 1 DHAP

Question 8

importance of phosphorylating glucose as first step of glycolysis

Answer 8

so that glucose cannot leave cell
reduce concentrations of glucose in cell so that more comes

Question 9

2 priming reactions in preparatory phase

Answer 9

phosphorylation of glucose by hexokinase to glucose 6-phosphate (step 1)
and phosphorylation of fructose-6-phosphate to fructose 1,6-bisphosphate (step 3)

Question 10

glycolysis phosphorylation of glucose

Answer 10

step 1: C6 nucleophilic oxygen attacks phosphate of ATP
1 ATP consumed producing glucose-6-phosphate
thermodynamically favorable/irreversible
catalyzed by hexokinase and Mg2+
regulated by substrate inhibition

Question 11

glycolysis phosphohexose isomerization

Answer 11

step 2: conversion of glucose 6-phosphate to fructose 6-phosphate (aldose to ketose)
catalyzed by phosphohexose isomerase and Mg2+
slightly unfavorable/reversible
easier to phosphorylation and symmetrical molecule

Question 12

glycolysis phosphorylation of fructose 6-phosphate

Answer 12

step 3: phosphorylation of fructose 6-phosphate to fructose 1,6-bisphosphate
catalyzed by PFK-1 and Mg2+, 1 ATP consumed
thermodynamically favorable/irreversible
highly regulated by availability of ATP (high ATP, no reaction)

Question 13

glycolysis cleavage of fructose 1,6-bisphosphate

Answer 13

Step 4: fructose 1,6-bP cut in half to the right of O and C3/C4 creating glyceraldehyde 3-phosphate (GAP) (aldose) and dihydroxyacetone phosphate (ketose)
catalyzed by aldose
end of preparatory phase
thermodynamically unfavorable, reversible
product concentration kept low to pull rxn forward

Question 14

glycolysis triose phosphate interconversion

Answer 14

Step 5: first step of payoff phase
conversion of dihydroxyacetone phosphate (DHAP) into a 2nd GAP molecule
only GAP is substrate for next step in pathway
catalyzed by triose phosphate isomerase
thermodynamically unfavorable/reversible
product concentration kept low to pull rxn forward

Question 15

glycolysis GAP dehydrogenase

Answer 15

Step 6: oxidation of GAP to 1,3-bisphosphoglycerate
1 NADH produced (energy yielding step)
catalyzed by glyceraldehyde 3-phosphate dehydrogenase
thermodynamically unfavorable, reversible
coupled to step 7 to pull it forward

Question 16

glycolysis 1st production of ATP

Answer 16

Step 7: phosphate transfer from 1,3-bisphosphoglycerate to 3-phosphoglycerate + 1 ATP
catalyzed by phosphoglycerate kinase and Mg2+
thermodynamically favorable/irreversible
ex. of substrate level phosphorylation

Question 17

glycolysis migration of phosphate

Answer 17

Step 8: 3-phosphoglycerate phosphoryl group moves from C2 to C3 to make 2-phosphoglycerate
catalyzed by phosphoglycerate mutase and Mg2+
thermodynamically unfavorable, reactant concentration kept high
reactant concentration kept high to push rxn foward

Question 18

mutases

Answer 18

catalyze migration of functional groups

Question 19

glycolysis dehydration from 2-phosphoglycerate

Answer 19

Step 9: 2-phosphoglycerate dehydrated to phosphoenolpyruvate (better phosphate donor)
catalyzed by enolase
thermodynamically unfavorable/reversible
dehydration, water released
product concentration kept low to pull reaction forward

Question 20

glycolysis 2nd production of ATP

Answer 20

Step 10: phosphoenolpyruvate gives phosphoryl group to form 1 ATP and pyruvate
tautomerization occurs afterwards, decreasing product concentration
catalyzed by pyruvate kinase and Mg2+, Mn2+, K+
highly thermodynamically favorable, irreversible
regulated by ATP, divalent metals

Question 21

types of phosphorylation compared

Answer 21

substrate level - ATP produced by enzyme catalyzed transfer of phosphate group to ADP from intermediate

oxidative phosphorylation - proton gradient provides energy for membrane protein ATP synthase to phosphorylate ADP

Question 22

glycolysis regulation

Answer 22

high ATP binds to regulatory binding site on step 3 enzyme phosphofructokinase

Question 23

total products made from glycolysis

Answer 23

2 pyruvate, 4 ATP (2 net), 2 NADH

Question 24

irreversible steps of glycolysis

Answer 24

Step 1: C6 nucleophilic oxygen attacks phosphate of ATP producing glucose-6-phosphate, 1 ATP consumed

Step 3: phosphorylation of fructose 6-phosphate to fructose 1,6-bisphosphate

Step 10: phosphoenolpyruvate gives phosphoryl group to form 1 ATP and pyruvate

Question 25

which steps have covalently bound enzyme intermediates?

Answer 25

Aldolase and glyceraldehyde-3-phosphate dehydrogenase

Question 26

high energy intermediates in glycolysis

Answer 26

1,3-bisphosphoglycerate and phosphoenolpyruvate (precursors to steps 7 and 10 production of ATP from ADP)

Question 27

which glycolysis reactions is Mg2+ present?

Answer 27

Steps 1-3, 7, 8 and 10

Question 28

when is dehydration reaction in glycolysis?

Answer 28

step 9: 2-phosphoglycerate to phosphoenolpyruvate

Question 29

thermodynamically favorable steps

Answer 29

all involving ATP production or use
Steps 1, 3, 7 and 10