lecture 4: glycolysis, nad, Redox reactions and pyruvic and lactic acid Flashcards
explain substrate level phosphorylzation and its use
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
give an example of substrate level phosphorylation in glycolysis
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
at rest, is glycolysis inhibited or activated
inhibited
what are the two regulators/inhibitors of glycolisis cycle
negative feedback of hexokinase
hgih energy charge inhibition
explain glycolysis at rest
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)
what are the 3 enzymes that are inhibited if at rest/adequate glucose
hexokinase
phosphofructokinsase
pyruvate kinase
during inhibition of glycolysis, does breakdown stop complelett?
no . there is always little amounts of ATP being made
what are the 2 factors that stimulate glycolysis
low energy chanrge (pfk)
feed forward stim (fructose 1-6 and phosphoenolpyruvate)
explain glycolisis being stimulated
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
what are the 2 options for pyruvate after stimulated glyoclusis
kreb cycle (for long slow run) lactate (sprint)
ATp and H will inhibit or stimulate phosphfructokinase and pyruvate kinsase
inhibit
ADP and AMP will inhibit or stimulate phosphfructokinase and
stimulate
what enzyme is the rate limiting ezyme of glycolisis and what does that mean
phosphofructokinase
PFK when activated is the central controller of glycolysis (determines how much atp being formed)
what is NAD+ (name)
nicotinatmide adenine dinucelotide
structure of NAD
2 nucleotides
1 nicotinatmide
1 adenine
NAD is a co…
coenzyme/cofactor
what is NAD (function)
it is an electron carrier and binds protons to the N+
what would happen if Nad+ did not go to NADH
glycolysis would come to a hault
what is oxidfation
loss of electrons
what is reductions
gaining of electrons
is NAD+ in oxidized or reduced form
oxidized form (lost its electron)
is NADH in its reduced form or oxidized form
reduced form (bound electrons)
explain the redox oxidation reaction for NAD+ to NADH
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)
why are the elcetrons and hydrogens important in NAD and NADH
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)
where does NAD+ get the electrons and hydrogen to become NADH in glycolysis
from the glyceraldehyde 3 phosophate
why is NAD+ important for glycolysis (in terms of lactate)
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
what happens without the NAD+ being there to accept the Hydrogens
accumulation of hydrogens in the cell, PH will drop and cell function will start to cease (glycolysis will stop)
what is lactic acid (
end product of anerobic metablosm
pyruvate with 2 added hydrogens
do we need hydrogen for glycolis
we dont NEED
what os the relationship between intensity anf lactate concentration
as intensity increases, lacttate concentration increases
explain lactate and exercise
at lower levels, glycolysis is happening but there is even concenrtrations of nadh and nad until you reach a lactate threshold
At harder exercise: glycolysis will be increasing at a very high rate therefore you will be producing a lot of NADH going to lacate (and reducing number of NAD+ available to pick up hydrgens)
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 freee Hydrogen will compete with calcium for active sports and then you will get fatuigued
=GLYCOLYSIS WILL SLOW DOWN
during high internsity exercise and, where does the majority of pyruvate get converted into
under what conditions does this happen
lactic acid
inadequate o2 consumption
where does the remainder of the pyruvate that doesnt go to lactic acid get transformed into>
mitochomdira tp be transformed into acetyl Ca
once pyruvate enters the mitochondria, it is the start of what process
OXIDATION
During low intensity execrise, where does pyruvate go
during what conditions
MOST OF IT gets converted to actyl coa to do oxidation
adequate o2 oxidation
WHAT ORGAN does pyruvate go if it does not go to lactic acid
MITOCHONDIRA
where and how does pyruvate get taken up in the mitcodhonria
into the mitochondra by a transport protein at the inner membrane
what is the first thing that happnes to pyruvate when it eners the matric of the cell
loses a co2 which is expired from the lungs
what is the second step when pyruvate enters the cell
there is a reduction reaction of NAD+ to NADH
what is the third step when pyruvate enters the cell
a coenzyme (with a sulfer group) attached to where the carbon once was and we form acetyl coa
is forming acetyl co-a fairly sponteanoue or not
yes it is
what happens with the acetyl coa that is formed from pyrvate
it enters the kreb cycle
after glycolysis, how many puyrvates are entereing the mitochondra and how many acetyl coa are goig to kreb
2 and 2
