Lecture 1 Glycolysis Flashcards
What is AMP
AMP + P -> ADP, ADP + P = ATP
What is creatine phosphate
its high energy molecule stored in muscles used in the rapid production of ATP in times of high energy demand. creatine in the body makes creatine phosphate
Why is glycolysis a core metabolic pathway
- Provides rapid energy in times of no oxygen
- acts as intermediate for other processes
How should glycolysis enzymes balance?
Balance between energy needs of the cell and making precursors for other processes?
When should glycolysis be turned on and off?
To make other precursors?
- Not enough precursors: make more
- Enough precursors: glycolysis can slow down
Energy:
Low energy -> more glycolysis
AMP is the low energy status
ATP is the high energy status
What is the negative and postive control of regulatory step in step 1?
Negative regulator: Glucose 6-P (negative feedback)
What is the negative and postive control of regulatory step in step 3? Frutose-6-P -> Frutose 1-6 bisphosphate?
(+): F-2,6-BP
(+): AMP
(-): ATP
(-): Citrate
(-): H+
What is the negative and postive control of regulatory step in step 10? phosphoenol pyruvate -> pyruvate?
(+): F-1,6-BP (feedforward)
(-): ATP
(-): Alanine
How do regulators of control point affect the enzyme?
It affects the enzyme kinetics - making the reaction go slower or faster.
How do different tissues control the pathway differently?
Different tissues control the pathway in different ways
How is glycolysis in the muscles regulated?
How is phosphofructokinase regulated?
How is hexokinase regulated?
How is pyruvate kinase regulated?
It is regulated to meet energy needs.
Primary regulation is by ATP/AMP ratiods
Energy needs change rapidly
- PFK is regulated by ATP and AMP
- Hexokinase is regulated by negative feedback
- Pyruvate kinase is regulated by ATP and feedforward activation
How is PFK controlled?
ATP and AMP compete for binding to the regulatory site
How does ATP/AMP binding affect PFK?
Glycolysis in muscles is tightly linked to
The need for ATP
When does Glycogen enter glycolysis
via Glucose-6-p
How is glycolysis in the liver regulated? How is PFK, Hexokinase/glycokinase regulatoed, pyruvate kninase
The Liver has more diverse biochemical functins than the muscle (detoxification, maintianing blood-glucose).
PFK, in addtion to ATP, is regulated by intermediates of other pathways.
Hexokinase and glucokinase (isoenzymes)
Pyruvate kinase in the liver is regulated allosterically and by covalent modification.
Regulation by metabolic intermedites, as well as hormonal regulation
How is glycolsyis in the liver regulated?
by other metabolic intermediates/hormal
How is PFK regulated via ATP/AMP?
Allosteric binding
Why does glycolsyis in liver control need to override ATP regulation?
Because it doesnt experience sudden changes in ATP/ADP
How is pyruvate kinase regulation different in muscles vs. liver
pyruvate is regulated by ATP/AMP (allosteric). in the liver, it is also phosphorylated
Difference between hexokinase and glucokinase
- Glucokinase has a lower affinity for glucose than hexokinase (lower Km)
- Glucokinase has higher specificity for glucose (hexokinase can phosphorylate mannose and fructose)
- Glucokinase is not inhibited by Glucose-6-P (can act in high levels of glucose).
Therefore, when blood sugar is high, glucokinase can act and quicly remove the sugar from the blood
Difference between Glucagon and Glycogen
Glucagon: is the hormone
Glycogen: stored sugar
When is glucagon/insulin acgivated
Glucagon is activated when blood sugar is low. Liver releases glucose (from glycogen)
insulin is triggered when blood sugar is high. Triggers cells to Absorb some of the glucose from the blood. In the liver (glucose -> glycogen)
How is PFK regulated in the liver
Liver: does not respond to ATP quickly -> regulate by metabolic intermeidates
Citrate (-): indicate we have enough precursors -> slows down glycolysis
F-2,6-BP (+): production of F-1,6-BP -> signals theres sugar in the blood -> glucose should speed up
