lecture 10 glycolysis

Question 1

hexokinase reaction and what it does energetically

Answer 1

Traps Glucose in the Cell and Begins Glycolysis. phosphorylates any glucose that enters cell to create glucose-6-phosphate. ATP–> ADP

Question 2

Phosphofructokinase (PFK) reaction

Answer 2

fructose 6-phosphate -> fruc 1,6 bisphosphate. turns ATP into ADP. part of stage 1 of glycolysis

Question 3

pyruvate kinase reaction

Answer 3

last step of glycolysis. phosphoenolpyruvate –> pyruvate, generates 4 ATP’s as each of the ADP’s get phosphorylated

Question 4

hexokinase phosphorylates glucose at what position?

Answer 4

c6

Question 5

hexokinase is an example of ___ coupling

Answer 5

enzymatic

Question 6

how does the hexokinase enzyme work?

Answer 6

brings both substrates together in the active site so that OH faces the gamma ATP and then wraps around them so tightly that no water molecule can get through

Question 7

why would it be bad if water got into the active site?

Answer 7

premature hydrolyzing of atp before we can obtain our energy from it

Question 8

is phosphofructokinase reaction reversible or irreversible

Answer 8

irreversible

Question 9

what step in glycolysis involves NAD+

Answer 9

1,3 BPG

Question 10

1,3-bisphosphoglycerate has a greater _____ than ATP, and thus can be used to power the synthesis of ATP from ADP and Pi

Answer 10

phosphoryl transfer potential

Question 11

___ is material in the first step that involves ATP formation

Answer 11

1,3 BPG

Question 12

metabolic coupling

Answer 12

happens on subsequent enzymes rather than same enzymes- pulls reaction forward through its negative delta G or le chat’s principle

Question 13

how can you regenerate NAD+ to keep glycolysis going?

Answer 13

NAD+ can be regenerated by further oxidation of pyruvate to CO2, or by the formation of ethanol or lactate from pyruvate.

Question 14

fermentation is a means of oxidizing __

Answer 14

NADH

Question 15

The conversion of glucose into 2 molecules of lactate is called

Answer 15

lactic acid fermentation.

Question 16

when oxygen is present, NADH does what?

Answer 16

When oxygen is present NADH donates electrons to another molecule to shuttle them into the mitochondrial matrix for use and gets reoxidized to NAD+ in the process.

Question 17

When oxygen is not present, what happens?

Answer 17

animal cells transfer the electrons and two protons onto pyruvate to form lactate, and thereby reoxidizeing NAD+ in the process.
Yeast transfers electrons onto acetaldehyde to produce ethanol.
Generating energy in absence of oxygen is called fermentation. Glucose to lactate is called lactic acid fermentation.

Question 18

____controls efflux from the pathway and is also inhibited by high energy charge.

Answer 18

pyruvate kinase

Question 19

____ raises free energy level and traps hexose in ketose form to make next step of cleavage in half more possible. The cleavage remains + ΔGo value, however, and moves forward by metabolic coupling (Le Chatlier’s principle in play) since overall ΔGo is negative. reaction is irreversible.

Answer 19

Phosphofructokinase

Question 20

stages of glycolysis: first stage

Answer 20

glucose –> fructose –> fructose 6 phosphate –> F6biphosphate–> chopped in half, to form glyceradlehyde 3-phosphate

Question 21

second stage of glycolysis

Answer 21

the two glyceraldehyde 3-phosphates are oxidized to acids as NAD+ is reduced, and each gets another phosphate group- now they each have two

Question 22

role of PFK

Answer 22

adds a phosphate group onto F6phosphate to turn it into fructose 1,6 biphosphate

Question 23

stage 3 glycolysis

Answer 23

Stage 3 moves each of the four phosphates onto 4 molecules of ADP to form ATP. Net gain = 2 ATP

Question 24

which reaction in glycolysis involves NAD+? aka the ‘money step’

Answer 24

glyceraldehyde 3-phosphate –> 1,3 bisphosphoglyerate.

we took a phosphate from the cytoplasm and plopped it on GAP. we get the energy to do this from the oxidiation of NAD+ . enables rxn to go. redox ‘electron acceptor’ is NAD+

an acid w/ high phosphoryl transfer potential, 1,3-bisphosphoglycerate, is generated by the oxidation of GAP in a reaction catalyzed by glyceraldehyde 3-phosphate dehydrogenase

Question 25

T/F: 1,3-bisphosphoglycerate has a greater phosphoryl transfer potential than ATP

Answer 25

true - that is how we create ATP for the first time in glycolysis . powers the synthesis of ATP from ADP and P

Question 26

the formation of ___ generates ATP in glycolysis

Answer 26

pyruvate

Question 27

T/F: Phosphoenolpyruvate is a high phosphoryl-transfer compound

Answer 27

true, thats how we power ATP formation

Question 28

how many atp’s are formed in glycolysis (net)

Answer 28

2

Question 29

how can we regenerate NAD+ to continue glycolysis if we have used up all our NAD+?

Answer 29

make lactate , ethanol, or acetyl coA

Question 30

fermentations are a means of oxidizing ___

Answer 30

NADH (so u can form NAD+)

Question 31

T/F: other sugars, like fructose and galactose, can enter glycolytic pathway and be converted into intermediates

Answer 31

true!