Metabolism And Energy Conversion

Question 1

Examples of catabolic pathways

Answer 1

-digestion
-glycolysis
-cellular respiration

Question 2

Examples of anabolic pathways

Answer 2

Biosynthesis

Question 3

Definition of metabolism

Answer 3

The sum total of all chemical reactions involved in maintaining the living state of the cells, and thus the organism

Question 4

Define anabolic reactions

Answer 4

Enzymes bring the substrate molecules together. Energy is needed to form these bonds-> Endergonic

Question 5

Define catabolic reactions

Answer 5

The enzyme active site affects the bonds in substrates so they are easier to break
Energy is released when the bonds are broken-> exergonic

Question 6

Define exergonic reactions

Answer 6

Energy is released to the surroundings. The bonds being formed are stronger than the bonds being broken

Question 7

Define Endergonic reactions

Answer 7

Energy is absorbed from the surroundings. The bonds being formed are. Weaker than the bonds being broken

Question 8

How does ATP store energy

Answer 8

Phosphoenhydride bonds- high in potential energy as there are negative charges on the oxygens, making it thermodynamically unstable.

Question 9

What is activation energy

Answer 9

A energy barrier in ATP that prevents the first phosphate of ATP from spontaneously breaking off as inorganic phosphate and leaving behind AFP

Question 10

Why is ATP kinetically stable

Answer 10

Activation energy for ATP hydrolysis is high
Phosphate group must be stolen by a water molecule for it to be broken off. Phosphate molecule pushes water molecule away as the negative charges on both repel.

Question 11

What is the role of a certain enzyme in breaking down ATP

Answer 11

ATPase catalyses the hydrolysis of ATP. Lowers the activation energy

Question 12

Give examples of energy carriers

Answer 12

NAD+ and NADP+

Question 13

What is the phosphoryl group-transfer potential

Answer 13

ATP has a high phsophoryl group-transfer potential as ATP has a high tendency to transfer its phosphoryl group to water

Question 14

Outline the steps in stage 1 of glycolysis (Energy investment)

Answer 14

Hexokinase - transfer a phosphoryl group from ATP to glucose to form glucose 6-phosphate

Phosphoglucose isomerase - causes isomerisation of glucose-6-phosphate to fructose-6-phosphate.

Phosphofructokinase - transfer a phosphoryl group from ATP to the hydroxyl group on C1 of fructose-6-phosphate forming fructose-1,6bisphosphate

Question 15

Outline the steps in stage 2 of glycolysis (Splitting)

Answer 15

Aldolase splits fructose 1,6-bisphosphate (6 C) into 2 three-C molecules, glyceraldehyde 3-phosphate and dihydroxyacetone phosphate

Question 16

Outline the steps in stage 3 of glycolysis (energy payoff phase)

Answer 16

Glyceraldehyde-3-phosphate dehydrogenase - glyceraldehyde 3-phosphate is phosphorylated via oxidation of the aldehyde group. Reduction of NADH

Phosphoglycerate kinase - transfers phosphoryl group Fromm 1,3- bisphosphoglycerate. Generation of ATP

Phsophoglycerate muatse - shifts phosphoryl group from the 3 C to the 2 C position

Enlose - removes water from 2-phosphoglycerate to form phosphoenolpyruvate

Pyruvate kinase - transfers phosphoryl group from phosphoenolpyruvate to ADP. Generation of ADP

Question 17

What is the net reaction of glycolysis:

Answer 17

Glucose + 2NAD + 2 P + 2 ADP+ 2 Pyruvate + 2ATP + 2 NADH + 2H2O