lecture 4: glycolysis, nad, Redox reactions and pyruvic and lactic acid

Question 1

explain substrate level phosphorylation and its use

Answer 1

use it to manufacture ATP
Substrate(with a bound phosphtte) and ADP are bound to the enzyme
enzyme causes substrate to donate the phosphate to the ADP
Product is now formed and atp

Question 2

give an example of substrate-level phosphorylation in glycolysis

Answer 2

phosphoenolpyruvate to pyruvate

phosphoenolpyruvate is bound to the enzyme with ADP
it donates the phosphate to ADP
Atp is formed and the product pyruvate is formed

Question 3

at rest, is glycolysis inhibited or activated

Answer 3

inhibited

Question 4

what are the two regulators/inhibitors of glycolysis cycle

Answer 4

negative feedback of hexokinase

hgih energy charge inhibition

Question 5

explain glycolysis at rest

Answer 5

At rest, there will be an accumulation of glucose going to glucose 6 phosphate which will cause a negative feedback on hexokinase and promote glycogen

At rest, there will be a high energy chanrge in the cell (more ATP than AMP) which will inhit phosphofrcutose kinase (stops frcutose 6 to going to 1-6) and will also inhibit pyruvate kinase (stops phosphoenolpyruvate to pyruvate)

Question 6

what are the 3 enzymes that are inhibited if at rest/adequate glucose

Answer 6

hexokinase
phosphofructokinsase
pyruvate kinase

Question 7

during inhibition of glycolysis, does breakdown stop completely?

Answer 7

no . there is always little amounts of ATP being made

Question 8

what are the 2 factors that stimulate glycolysis

Answer 8

low energy chanrge (pfk)

feed forward stim (fructose 1-6 and phosphoenolpyruvate)

Question 9

explain glycolysis being stimulated

Answer 9

During activity, alot of glucose going to glucose 6 (hexokinase will speed up)
Since there is a low energy charge in the cell (build of AMP since ATP is being hydrolized) this will stimulate frcutose 6 to go to fructose 1-6
fructose 1-6 will begin to be depleted and pyruvate kinase will be stimulated to make a lot of pyruvate
pyruvate can go down two paths depending on activaty

Question 10

what are the 2 options for pyruvate after stimulated glycolysis

Answer 10

kreb cycle (for long slow run)
lactate (sprint)

Question 11

ATP and H will inhibit or stimulate phosphofructokinase and pyruvate kinase

Answer 11

inhibit

Question 12

ADP and AMP will inhibit or stimulate phosphofructokinase and

Answer 12

stimulate

Question 13

what enzyme is the rate-limiting enzyme of glycolysis and what does that mean

Answer 13

phosphofructokinase

PFK when activated is the central controller of glycolysis (determines how much atp being formed)

Question 14

what is NAD+ (name)

Answer 14

Nicotinamide adenine dinucleotide

Question 15

structure of NAD

Answer 15

2 nucleotides
1 nicotinatmide
1 adenine

Question 16

NAD is a co…

Answer 16

coenzyme/cofactor

Question 17

what is NAD (function)

Answer 17

it is an electron carrier and binds protons to the N+

Question 18

what would happen if Nad+ did not go to NADH

Answer 18

glycolysis would come to a hault

Question 19

what is oxidation

Answer 19

loss of electrons

Question 20

what is reductions

Answer 20

gaining of electrons

Question 21

is NAD+ in oxidized or reduced form

Answer 21

oxidized form (lost its electron)

Question 22

is NADH in its reduced form or oxidized form

Answer 22

reduced form (bound electrons)

Question 23

explain the redox oxidation reaction for NAD+ to NADH

Answer 23

NAD+ lost its electrons/hydrogens
2 H from food is broken down to 2 electrons and 2 H+
2 electrons will bing to the N+
1 hydrogen proton will add to the binding and one will be “as a product)

Question 24

why are the electrons and hydrogens important in NAD and NADH

Answer 24

electrons can be donated to the electron transport chain for enery
hydrogens can accumulate and start to compete for active sites in the muscles agaisnt calcium =be fatigued)

Question 25

where does NAD+ get the electrons and hydrogen to become NADH in glycolysis

Answer 25

from the glyceraldehyde 3 phosophate

Question 26

why is NAD+ important for glycolysis (in terms of lactate)

Answer 26

GLyceraldehyde 3P gives its electrons and hydrogen to the NAD+ which becomes reduced to NADH

This NADH will be used later and will donate its electron and hydrogen to pyruvate to make lactate (catalyzed by lactate dehydrogenase)

Left with NAD+ again whcih can refeed into the cycle of glycolysis

Question 27

what happens without the NAD+ being there to accept the Hydrogens

Answer 27

accumulation of hydrogens in the cell, PH will drop and cell function will start to cease (glycolysis will stop)

Question 28

what is lactic acid

Answer 28

end product of anerobic metablosm

pyruvate with 2 added hydrogens

Question 29

do we need hydrogen for glycolysis

Answer 29

we dont NEED

Question 30

what is the relationship between intensity and lactate concentration

Answer 30

as intensity increases, lacttate concentration increases

Question 31

explain lactate and exercise

Answer 31

at lower levels, glycolysis is happening but there is even concentrations of NADH and nad until you reach a lactate threshold

At harder exercises: glycolysis will be increasing at a very high rate therefore you will be producing a lot of NADH going to lactate (and reducing the number of NAD+ available to pick up hydrogens)

At Maximal exertion: glycolysis is going at very rapid rates, and NADH will be at high concentration but there will start to be an accumulation of H+ (because of lack of NAD+)

Accumulation of free Hydrogen will compete with calcium for active sports and then you will get fatigued

=GLYCOLYSIS WILL SLOW DOWN

Question 32

during high-intensity exercise and, where does the majority of pyruvate get converted into
under what conditions does this happen

Answer 32

lactic acid

inadequate o2 consumption

Question 33

where does the remainder of the pyruvate that doesn’t go to lactic acid get transformed into>

Answer 33

mitochondria to be transformed into acetyl Ca

Question 34

once pyruvate enters the mitochondria, it is the start of what process

Answer 34

OXIDATION

Question 35

During low intensity exercise, where does pyruvate go

during what conditions

Answer 35

MOST OF IT gets converted to actyl coa to do oxidation

adequate o2 oxidation

Question 36

what organ does pyruvate go if it does not go to lactic acid

Answer 36

MITOCHONDIRA

Question 37

where and how does pyruvate get taken up in the mitochondria

Answer 37

into the mitochondria by a transport protein at the inner membrane

Question 38

what is the first thing that happens to pyruvate when it enters the matrix of the cell

Answer 38

loses a co2 which is expired from the lungs

Question 39

what is the second step when pyruvate enters the cell

Answer 39

there is a reduction reaction of NAD+ to NADH

Question 40

what is the third step when pyruvate enters the cell

Answer 40

a coenzyme (with a sulphur group) attached to where the carbon once was and we form acetyl coa

Question 41

is forming acetyl co-a fairly spontaneous or not

Answer 41

yes it is

Question 42

what happens with the acetyl co-a that is formed from pyruvate

Answer 42

it enters the kreb cycle

Question 43

after glycolysis, how many pyruvates are entering the mitochondria and how many acetyl coa are going to kreb

Answer 43

2 and 2