Energy Production-carbs 3

Question 1

What are the functions of glycolysis?

Answer 1

Oxidation of glucose
NADH production
Synth ATP from ADP
Produce C6 and C3 itemediates

Question 2

What are the features of glycolysis?

Answer 2

Can=enteral pathway of CHO metabolism 
Occurs in al cells cytoplasm
Exergonic, oxidative
No loss of CO2
Can operate anearobically with LDH
Irreversible

Question 3

What is allosteric enzyme regulation?

Answer 3

An activator or inhibitor bins at “another” site in metabolic regulation.

Enzymes have 2+ sites a catalytic site and a regulatory site
Regulatory site= binding of a specific regulatory molecule can activate or inhibit

Question 4

What is covalent modification of an enzyme?

Answer 4

Introduction or removal of a bulky negatively charged PO4(2-) moiety
It alters the structure (protein conformation) which then alters activity

Question 5

Describe a reversible step in metabolic pathways (and their regulation)

Answer 5

They are not regulated (as equilibrium is dynamic it will always be reached)
This means levels of product are unaffected

Question 6

Describe an irreversible step in a metabolic pathway (and its regulation)

Answer 6

Potential site of regulation
Reduced activity reduces the flux of substrates through the pathway directly
Therefore reducing levels of product

Question 7

What is product inhibition?

Answer 7

If a product builds up it inhibits the steps above it in the reaction.
If C increases, it displaces B-C equilibrium towards B, this reduced rate of B binding to active site.
This reduced rate of catalysis of B to C

As conc of intermediates build flux through pathway is slow

Question 8

Describe feedback inhibition (a from of product nhinbitosn)

Answer 8

A product will inhibit an enzyme that lies above it in the pathway.
This reduces entry of substrate into the pathway and the build up of intermediates

Question 9

Describe the inhibition of a committing step in a metabolic pathway

Answer 9

Inhibition of committing step allows substrate to be diverted into other pathways rather than sitting unused.

Question 10

Describe hormone regulation in metabolic pathways

Answer 10

Hormone receptors nine.
Activates signalling pathways
Protien kinase (phosphorylation) or protien phosphatase (dephosphorylation) activated
De/phosphorylation of target enzyme
Alters protein conformation/activity +/-ve depending on target enzyme

Question 11

Describe feed forward regulation in metabolic pathway regulation.

Answer 11

Early pathway substrate provides positive allosteric signal to stimulate a later enzyme to activate the pathway.
It prepares the pathway to work

Question 12

Describe Adrenaline as a phosphoregulator

Answer 12

Activates protein kinase A

Phosphorylation activates phosphorylase kinase
Phosphorylation of glycogen phosphorylase stimulates glycogen breakdown

Question 13

Describe insulin as a phosphoregulator

Answer 13

Dephosphorylates/activates pyruvate dehydrogenase to stimulate glucose use

Dephosphorylates glycogen phosphorylase to inhibit glycogen breakdown

Question 14

Name the key regulator in glycolysis

Answer 14

Phosphofructokinase

Question 15

List the types of regulation of phosphofructokinase

Answer 15

Allosteric regulation (Muscle) =
Inhibited by ATP, stimulated by AMP

Hormonal regulation (liver) = 
Stimulated by insulin, inhibited by glucagon

Question 16

How does NADH regulate glycolysis

Answer 16

High NADH conc=high energy levels
Causes product inhibition of step 6
And thereby inhibits glycolysis

Question 17

How is phosphofructokinase phosphoregulated?

Answer 17

Insulin leads to dephospholylation of enzyme= stimulates it

Glucagon leads to phosphorylation of enzyme= inhibits it

Question 18

Summaries the regulation of the glycolytic pathway

Answer 18

Metabolic regulation=.
High NADH/low NAD=inhibits step 6
High ATP inhibits PFK
High AMP stimulates PFK

Hormonal regulation=
A high insulin:glucagon ratio activates PFK and Pyruvate kinase in enzyme dephosphorlyation.

Question 19

Where is the committing step in glycolysis?

Answer 19

Step 3-PFK

When energy is high glycolysis stops and the molecules instead enter the shunt () creating biosynth materials and NADP to feed back into the cycle instead of more ATP. This is more useful to the cell than a continuous ATP made.