Energy Reactions In Cells

Question 1

Where do metabolic pathways occur?

Answer 1

In the cell cytoplasm. This is also where they are regulated.

Question 2

What happens if a metabolic reaction needs to segregated from other reactions?

Answer 2

It will be restricted to a particular part of the cell.

Question 3

Why do catabolic processes result in the release of large amounts of energy?

Answer 3

They involve the breaking of chemical bonds, breaking down

Larger molecules into smaller ones.

Question 4

Are catabolic processes oxidative or reductive?

Answer 4

Oxidative. They release reducing power in the form of H atoms.

Question 5

What drives anabolic pathways?

Answer 5

ATP energy from catabolic pathways. They are reductive pathways and use the reducing power released in catabolism.

Question 6

Approximately how many calories does BMR use for a person at rest at 18 degrees?

Answer 6

1400 - 1700 kcal

Question 7

How much energy do we use in one day for ingestion, digestion and absorption of food?

Answer 7

150kcal

Question 8

If man is isotherm if and cannot use heat to drive reactions, where does energy for reactions come from?

Answer 8

Chemical bond energy

Question 9

What is the difference between an Exogenic and an endogenic reaction?

Answer 9

Exogenic reactions release energy whilst endogenic reactions require energy.

Question 10

What are the three H carrier molecules?

Answer 10

NAD+ –> NADH
NADP+ –> NADPH
FAD –> FADH2

Question 11

Why do energy cycles occur with H carriers?

Answer 11

There are only a limited number of carriers and so a cycle must occur because they take up H atoms and then release them so that they can take up more H atoms from catabolic processes.

Question 12

What does NADPH carry reducing power for?

Answer 12

Biosynthesis

Question 13

Give an example of an indirect coupling system.

Answer 13

In the mitochondria, the systems are coupled to produce ATP from NADH but this is indirect because it involves two separate processes. An example of a direct coupling system is the use of NADPH is biosynthesis.

Question 14

Why is the stability of ATP important?

Answer 14

It controls energy flow and holds onto energy when it is not requires which means energy from catabolic processes has nowhere to go and they slow.

Question 15

How is ATP an energy carrier?

Answer 15

The energy is held in the high energy bond of hydrolysis of the terminal phosphate.

Question 16

Define Metabolism.

Answer 16

A set of process which derive energy and raw materials from food and use it to support growth, repair and activity of tissues to sustain life.

Question 17

What is a high energy signal in a cell and what does this cause?

Answer 17

High concentration of ATP.

This stimulates anabolism as there is sufficient energy for synthesis

Question 18

Name two low energy signals and state the reaction by which one is formed.

Answer 18

ADP
AMP
When energy is really low, 2ADP –> ATP + AMP to provide a little more energy.

Question 19

When there are low energy signals in a cell, what form will H carriers be in?

Answer 19

Their reduced form: NAD+, FAD, NADP+

Question 20

What is the high energy store in skeletal muscle and why is this needed?

Answer 20

creatinine phosphate. It is needed because there can be a very sudden increase in metabolic activity.

Question 21

Creatine + ATP –> Creatine Phosphate + ADP

State the enzyme in this reaction and when this reaction occurs.

Answer 21

Creatine Kinase.
This occurs when ATP levels are high and means that more catabolic processes can occur because ATP is recycled back to ADP.
When ATP falls this reaction reverses.

Question 22

What is a useful marker in the blood of MI?

Answer 22

Creatine Kinase. When there is damage to the heart tissue this enters the blood stream.

Question 23

Creatinine is found in the urine. What is it and why is it useful?

Answer 23

It is the breakdown product of Creatine and a useful indicator of muscle wastage. (Under normal conditions it is proportional to muscles mass). It is a good indicator for comparing loss of other substances too (e.g. Pregnancy hormones).