Glycolysis

Question 1

What is Glycolysis and where does it take place?

Answer 1

The break down of glucose into smaller molecules (pyruvate), so producing ATP. It takes place in the cytoplasm

Question 2

Name some of the groups that often come up in talks about metabolism

Answer 2

Aldehyde (CO group at end of chain)
Ketone groups
Carboxyl groups

Question 3

Molecules ending in -ose are used to denote what kind of molecules?

Answer 3

Sugars

Question 4

Describe the structure of Glucose and Fructose

Answer 4

Glucose is also known as Kexose (sugar with 6 carbons) because is has six carbon atoms but tents to from a pyranose.
Fructose froms a 5-membered ring

Question 5

What does pyranose and furanose mean?

Answer 5

Pyranose - A saccharide that is a 6 membrered ring consisting of 5 carbon atoms and 1 oxygen
Furanose - Saccharide that is a 5 membered ring with 4 Carbon atoms and 1 oxygen

Question 6

Describe the step one of glycolysis? Glucose to glucose-6-phosphate

Answer 6

Glucose is phosphorylated and turned into glucose-6-phosphate which is an ionised molecule so it cannot pass through transporter molecules. A molecule of ATP is consumed.

Question 7

Describe the second step of glycolysis? Glucose-phosphate to fructose-6-phosphate

Answer 7

Isomerization causing glucose-6-phosphate to turn into fructose-6-phosphate. All that changes is the position of the carbonyl group

Question 8

Describe the third step of glycolysis? Fructose-6-phosphate to Fructose-1,6-bisphosphate

Answer 8

Phosphorylation of fructose-6-phosphate to fructose-1,6-bisphosphate. This molecule can be broken down into two phosphorylated 3-carbon compounds

Question 9

What is the fourth step of glycolysis?

Answer 9

Fructose-1,6-bisphosphate is broken down into glyceraldehyde-3-phosphate and a molecule of dihydroxyacetone phosphate which can then be broken down into glyceraldegyde-3-phosphate. At this point the reaction splits into two so you get two products

Question 10

Describe step 5 of glycolysis? Glyceraldehyde-3-phosphate to 1,3-bisphosphoglycerate

Answer 10

Oxidative phosphorylation.
Glyceraldehyde-3-phosphate is simultaneously oxidized and phosphorylated.
The hydrogen and electrons from glyceraldehyde-3-phosphate are transferred to NAH+ (nicotinamide adenine dinucleotide) to form NADH. Phosphate comes directly from cytosol

Question 11

Describe the importance of Nicotinamide adenine dinucleotide

Answer 11

It is an electron and proton acceptor. It is very significant in ATP production

Question 12

Describe what happens at step 6 of glycolysis. 1,3-bisphosphoglycerate to 3-phosphoglycerate

Answer 12

Transfer of Phosphate and ATP production!

2 molecules of ATP are produced

Question 13

Describe step seven of glycolysis. 3-phosphoglycerate to 2-phosphoglycerate

Answer 13

Molecular rearrangement (movement of phosphate group)

Question 14

Describe step eight of glycolysis? 2-phosphoglycerate to phosphoenol pyruvate

Answer 14

Dehydration. This favours the transfer of phosphate to ADP

Question 15

Describe the ninth and final step of glycolysis

Answer 15

Transfer of phosphate. Phosphoenol pyruvate is converted into pyruvate and two molecules of ATP is produced

Question 16

Under aerobic conditions what happens to NADH

Answer 16

NADH transfers electrons and hydrogen atoms to the electron transport chain so NAD+ is regenerated.

Question 17

What occurs in the absence of molecular oxygen?

Answer 17

NADH builds up because NAD+ cannot be regenerated

Question 18

Name some key enzymes in glycolysis and what they catalyse

Answer 18

Hexokinase - glucose to glucose-6-phosphate
Phosphofructokinase - Fructose-6-phosphate to fructose-1,6-phosphate
Pyruvate Kinase - Phosphoenol pyruvate to pyruvate

Question 19

What can phosphofructokinase be regulated by?

Answer 19

1) High ATP concs allosertically inhibits the enzyme
2) Low pH inhibits the enzyme
3) High citric acid concs inhibits
4) High fructose-6-phosphate stimulates the enzyme