Glycolysis Flashcards
Glucose to Glucose 6 Phosphate by ____
hexokinase
hexokinase ___ glucose —> G6P
phopshorylates
hexokinase is not present in the ___
liver, there is glucokinase
what happens wtih G6P?
there is no transporter for G6P so it is stuck at the cell
γ-Phosphoryl of ATP is transferred to the ___ of Glu by Hexokinase
C6 hydroxyl
when does the liver export glucose?
when glucose is low
this is why the liver has a less aggressive heokinase (glucokinase)
difference between affinity of glucokinase compared to heoxkinase?
Liver Glucokinase has an affinity for Glu that’s 500-fold weaker than that of Hexokinase
G6P enters glycolysis?
when the cell needs energy
G6P is converted to F6P by
phopshoglucose isomerase
action of phopshoglucose isomerase on G6P
PGI isomerizes an aldose to a ketose
after phopshorylation at the C1 hydroxyl group what is produced? why?
two equal 3 carbon fragments
due to PGI setting the stage for an aldol cleavage between C3/C4 (requires a carbonyl at C2)
phopshofructokinase transfers a γ-phosphoryl of ATP to the ___ of F6P to make it F1,6 BP
C1 hydroxy
fructose 6-phopshate is converted into F 1,6 BP by
phosphofructokinase
___ plays a central role in the regulation of Glycolysis
phopshofructokinase
what cleaves fructose 1,6, biphosphate
aldose
products?
what is dihydroxyacetone converted to?
GAP, the other product of the cleavage of f 16 BP
differene between DHAP and GAP?
DHAP is a KETOSE
GAP is an ALDOSE
what converts DHAP to GAP?
tripose-P-isomerase
GAP and DHAP are both
trioses
GAP gets ____ to be converted to 1,3-BPG by GAP dehydrogenase?
oxidized and phosphorylated
____ converts GAP to 1,3 BPG
GAP dehydrogenase
first step in glycolysis where you MAKE atp?
1,3 PBG is converted to 3PG by
phosphoglycerate kinase
how many ATPs does this rxn produce?
2
this is an example of ___
substrate level phopshorylation
Phosphoglycerate Mutase moves the phosphoryl of 3PG to the ____ to get ____.
C2 hydroxyl to give 2PG
___converts 3PG to 2PG
Phosphoglycerate Mutase
2PG is converted to PEP by
enolase
mechanism of conversion of 2PG by enolase to PEP
2PG is dehydrated
two examples of substrate level phopsphorylation
- 1,3-BPG to 3PG
2, **PEP to pyruvate **
describe the steps from GAP ————-> pyruvate
how many ATP are made from GLucose to Pyruvate?
4 ATP
what is the NET agian of ATP from glucose to two pyruvate
net gain of 2
what is the net gain of NADH from glucose to two pyruvate?
2 NADH
Under anaerobic conditions, pyruvate is reduced by glycolytic NADH to ___
give lactate
Under aerobic conditions, glycolytic NADH is ____ and pyruvate enters the CAC
indirectly oxidized by oxidative phosphorylation
enzyme that converts pyruvate to lactate?
lactate dehydrogenase
when pyruvate is being converted to lactate, the __ carbon of pyruvate get a hydride transer with a pronation of the hydroxyl rgroup
C2 carbon
galactose is converted to ___ to enter glycolysis
G6P
___ and ____ are converted to F6P to enter glycolysis
mannose and fructose
fructose is converted to ___ in the liver to enter glycolysis
GAP
order in which frucotse, galactose, and mannose enter the glycolsis pathway
what converts fructose to F6P in tissues other than the liver?
hexokinase
what converts fructose to 2GAP in the liver?
- Fructokinase
- F1P Aldolase
- Glyceraldehyde Kinase
- Trios-P Isomerase
Deficiencies in ___ cause liver damage and hypoglycemia
F1P Aldolase
Deficiencies in F1P Aldolase cause ___ and ___
liver damage and hypoglycemia
enzymes invovled in the conversion of mannose to F6P?
- hexokinase
- phopsomannose isommerase
enzymes invovled in teh converstion of galactose to G6p?
- Galactokinase
- a UMP Transferase
- an Epimerase
- Phosphoglucomutase
• A deficiency in ____ results in Galactitol formation which causes cataracts
Galactokinase
A deficiency in Galactokinase results in Galactitol formation which causes___
cataracts
A deficiency in the UMP transferase causes ____ (2)
mental retardation and liver failure
A deficiency in the _____ causes mental retardation and liver failure
UMP transferase
when second galactose
comes along,
the first is converted to ___
G1P
first step in breakdown of glycogen
glycogen phosphorylase
produces G1P
first step in conversion of G1P to glycogen?
UTP is added to G1P to pshoprylate it to become UDP-glucose
The phosphoryl of G1P condenses with the ____ of UTP to give UDP-Glu + PPi
α-phosphoryl
what is needed to pull the G1P to UDP-glucose reaction to completion?
pyrophosphatase cleaves PPi to 2Pi
The C4 hydroxyl of the Glu unit at the end of a Glycogen chain condenses with the___ carbon of UDP-Glu
C1
enzyme invovled in conversion of UDP-glucose to glycogen?
glucose synthase
from the a(1,4) terminal chains of glycogen
brnaching enzyme removes a 7 residue grafment from chaisn of at least ___ residues
11 (needs 4 left over)
branching enzymes converts from the a(1,4) terminal chains of glycogen to a ___ chain of glycogen
a(1-6) glycogen chain
this introduces a branch, so now have 3 branches instead of 2
Glycogen polymers may contain up to___ Glu units each
120,000
Glycogen polymers contribute up to ___ of the rotal mass of 10% of th eottal mass of the liver
10 percent
When Glu is needed, Phosphorylase breaks the glycosidic bond at the end of a Glycogen chain by addition of
a phosphate to give G1P
how long can glucose be removed from glycogen?
until terminal glucose on the chain is within 4 residues of a branch point where steric hinderance prevents further digestion by Phosphorylase
• Debranching enzyme transfers a ____ from the stub to the C4 hydroxyl at the end of another branch
trisaccharide
two functions of debranching enzyme?
- transfers a trisaccharide froms tub of c4 gtdroxyl at the end of another branch
- also cleaves the reamin a,16 glu by hydrolysis
difference betw Phsophoglucomutase in conversion of G1P to G6P and Phosphoglycerate Mutase in conversion of 3PG to 2PG?
Ser-P intermediate instead of His-P in Phsophylycomutase
cost of temproailry storing glu in glycogen in muscle/liver
from g6p -> glycogen -> g6p
