Glycolysis and Glycogen - IN Flashcards
this lecture blows.
what do you think of this lecture?
exactly! it blows.
general overview of steps 1-5 of glycolysis
glucose -> G6P -> F6P -> FBP -> DHAP -> GAP
phosphorylation, isomerization, phosphorylation, cleavage, isomerization
the phosphorylation steps req ATP
general overview of steps 6-10 of glycolysis
GAP -> 1,3 BPG -> 3PG -> 2PG -> PEP -> pyruvate
high energy compound generation, substrate level phosphorylation, rearrangement, high energy compound generation, substrate level phosphorylation
ATP is generated in both substrate level phosphorylation steps
NADH is made in first step
which substrate is a common branch point for numerous pathways?
G6P - synthesized to glycogen, pentose phosphate shunted to R5P, glycolyzed to pyruvate, synthesized into glucose
what enzyme completes step 1 of glycolysis, what type of reaction is it, and what happens in it?
hexokinase
phosphorylation, glucose + ATP –> G6P + ADP
what enzyme completes step 2 of glycolysis, what type of reaction is it, and what happens in it?
PGI - phosphoglucose isomerase
isomerization, G6P -> F6P
what enzyme completes step 3 of glycolysis, what type of reaction is it, and what happens in it?
Phosphofructokinase (regulation key)
phosphorylation, F6P + ATP –> FBP + ADP
what enzyme completes step 4 of glycolysis, what type of reaction is it, and what happens in it?
Aldolase
cleavage (lol)
FBP -> DHAP + GAP
what enzyme completes step 5 of glycolysis, what type of reaction is it, and what happens in it?
Triose Phosphate Isomerase
isomerization
DHAP -> GAP
what enzyme completes step 6 of glycolysis, what type of reaction is it, and what happens in it?
GAPDH
oxidation, phosphorylation
GAP + NAD -> 1,3 BPG + NADH
what enzyme completes step 7 of glycolysis, what type of reaction is it, and what happens in it?
PGK
substrate level phosphorylation
1,3 BPG + ADP -> 3PG + ATP
what enzyme completes step 8 of glycolysis, what type of reaction is it, and what happens in it?
Phosphoglycerate Mutase
Rearrangement
3PG -> 2PG
what enzyme completes step 9 of glycolysis, what type of reaction is it, and what happens in it?
Enolase
HE compound generation
2PG -> PEP
what enzyme completes step 10 of glycolysis, what type of reaction is it, and what happens in it?
Pyruvate Kinase
substrate level phosphorylation
PEP + ADP -> Pyruvate + ATP
glycolysis final notes
there is a net gain of 2 ATP and 2 NADH as glucose –> 2 pyruvates
what is the fate of glycolytic NADH under aerobic conditions
glycolytic NADH is indirectly oxidized by oxidative phosphorylation and pyruvate enters the citric acid cycle
what is the fate of glycolytic NADH under anaerobic conditions
pyruvate is reduced by glycolytic NADH to give lactate WHICH MAKES YOUR MUSCLES FUCKING TIRED, DUHHHHH
How does fructose enter the glycolytic pathway - note: fructose input is dependent on hexokinase or glucokinase presence
fructose is converted to glycolytic intermediate GAPx2 in liver
OR
fructose in muscle is converted to F6P to enter glycolysis
how does mannose enter glycolytic pathway?
same as fructose in muscles, mannose is converted to F6P
how does galactose enter glycolytic pathway
converted to G6P
what is cataracts
deficiency of galactokinase, so galactose cant enter glycolytic pathway, so galacticol forms -> cataracts
what does a UMP transferase deficiency cause
mental retardation, liver failure
must remove lactose from diet if pt has this
general overview of glycogen metabolism
G6P G1P –> UDP-Glucose –> Glycogen –> G1P
once this cycle occurs, glucose is primed to condense with growing glycogen polymer up to 120,000 GLU units
what is the priming step in glycogen synthesis and what enzyme does it use
G6P -> G1P
phosphoglucomutase
what is step 1 in glycogen synthesis and what enzyme does it use
G1P + UTP –> UDP-Glucose
UDP-Glucose pyrophosphorylase
what is step 2 in glycogen synthesis and what enzyme does it use
UDP-glucose -> condensation with glycogen polymer
glycogen synthase
note - C4 of gly chain & C1 of UDP-Glu condense to give A1,4 glycosidic bond
what is step 3 in glycogen synthesis and what enzyme does it use
branching of glycogen polymer
branching enzyme
note - BE makes a A1,6 bond at least 4 residues from other branches
what is step 1 in glycogen breakdown and what enzyme does it use
breaking down the polymer
glycogen polymer -> G1P
enz - glycogen phosphorylase
what is step 2 in glycogen breakdown and what enzyme does it use
debranches polymer
enz - phosphorylase
what is step 3 in glycogen breakdown and what enzyme does it use
G1P -> G1,6P -> G6P
enz - phosphoglucomutase
what are the costs of all this metabolism
- 1 ATP per G6P molecule broken down from glycogen in muscle
- 0 ATP per Glu molecule in liver
What is Von Gierke Disease
type 1 glycogen storage disease
defective enzyme G6Phosphatase
glycogen is increased in liver/kidney, gives hepatomegaly, hypoglycemia, ketosis, hyperlipidemia, failure to thrive
What is Anderson Disease
type 4 glycogen storage disease
defective enzyme branching enzyme A1,4 -> A1,6
glycogen is normal but very long outer branches -> progressive cirrhosis and liver failure/death before age 2
What is McArdle Disease
type 5 glycogen storage disease
def enz - phosphorylase
organ - muscle
glycogen is moderately increased, limited ability to exercise bc of painful muscle cramps
