Metabolism: Glycolysis And Pentose Phosphate Pathway

Question 1

What three types of pathways are there and their main functions?

Answer 1

1.Anabolic pathways - synthesis of compounds (requires energy)
2.Catabolic pathway - Breakdown of big molecules (produces energy like ATP breaking)
3.Amphibolic pathways - Connect both anabolic and catabolic pathways

Question 2

What many biological processes does glucose participate in?

Answer 2

-Formation of glycogen
-Source for Ribose (for DNA synth) and NADPH
-Formation of private (AA synth) and acetyl coA (precursor for FAs and Cholesterol)
-Formstion of triosphosphate necessary for glycerol formation

Question 3

Two types of glycolysis and their overview?

Answer 3

Aerobic glycolysis - in the presence of oxygen lead to formation of acetyl coA TCA cycle

Anaerobic glycolysis - in the absence of oxygen
Leads to lactic acid (final product)

Question 4

Glucose can’t diffuse directly into cells but has two ways to enter, what are the two?

Answer 4

1.Na+ independent facilitated diffusion transport system - (GLUT-1 to 14 are family of transporters using concentration gradient to move glucose)

2.Na+ monosaccharide cotransport system - energy requiring process that transports glucose against a gradient basically using symporter).

Question 5

Definition of glycolysis

Answer 5

Glycolysis is a sequence of reactions transforming glucose to lactate and pyruvate via ATP, end result is to produce energy and products for other pathways

1 molecule of glucose will result in 2 pyruvate

Site is cytosolic fraction of cell

Question 6

Quick overview of glycolysis

Answer 6

Once in the cell, glucose is phosphorylated by hexokinaxe

First five ‘preparatory’ steps consyme 2 x ATP in order to convert 1 molecule into 2 molecules of 3-carbon sugar phosphates

Second five ‘payoff’ steps produce 4 x ATP (2 net) and 2 x NADH

Question 7

What does lactate dehydrogenase (LDH) do?

Answer 7

Under anaerobic conditions pyruvate is converted to lactate by LDH

And the NAD+ frol lactate production allows glucose to continue by coming back to first steps

When O2 available again lactate can be converted back to pyruvate

Question 8

What does pyruvate dehydrogenase (PDH) do?

Answer 8

PDH converts pyruvate into Acetyl CoA

Which then enters the krebs cycle in the mitochondria