Energy Reactions in Cells

Question 1

Define metabolism.

Answer 1

The set of processes which derive energy and raw materials from food stuffs and use them to support repair, growth and activity of the tissues of the body to sustain life.

Question 2

Give a very brief overview of how nutrients reach desired cells.

Answer 2

Through the GI-tract the nutrients are absorbed into the blood and then transported into desired tissues.

Question 3

What are catabolic pathways?

Answer 3

Breakdown of larger molecules into smaller ones called intermediary metabolites
Release of large amount of free energy
Oxidative -> release H-atoms which are reducing power.

Question 4

What are anabolic pathways?

Answer 4

Synthesis of larger important cellular components from intermediary metabolites
Use energy released from catabolism (ATP)
Reductive (means it uses H atoms released from catabolism)

Question 5

What are the products of catabolic metabolism?

Answer 5

Building block materials like sugars, amino acids and fatty acids.
Organic precursors such as acetyl CoA
Biosynthetic reducing power (NADH, FADH2 and NADPH)
Energy for cell function (ATP)

Question 6

What is energy needed for?

Answer 6

Transport work
Anabolism
Mechanical work
Electrical work
Osmotic work

Question 7

What is an exergonic reaction?

Answer 7

A reaction that releases energy.

Question 8

What is an endergonic reaction?

Answer 8

A reaction that uses energy.

Question 9

What are some characteristics of an exergonic reaction?

Answer 9

They occur spontaneously
There is a change in free energy (deltaG)
deltaG < 0
Reactants -> products means a lower energy

Question 10

What are some characteristics of an endergonic reaction?

Answer 10

They do not occur spontaneously.
Energy is needed.
deltaG > 0
Reactants -> products means a higher energy.

Question 11

What are redox reactions?

Answer 11

Chemical bond energy of fuel molecules is released by oxidation reactions. All oxidations reactions are accompanied by a reduction reaction. This is called redox reaction.

Question 12

What is oxidation?

Answer 12

Removal of electrons or removal of h-atoms. (OIL RIG)

Question 13

What is reduction?

Answer 13

Gain of electrons. (OIL RIG = Oxidation is loss, reduction is gain)

Question 14

What are H-carrier molecules (reducing power)?

Answer 14

NAD+/NADH+H+
NADP+/NADPH+H+
FAD/FADH2

Question 15

What are reducing powers used for?

Answer 15

ATP production (NADH + H+)
Biosynthesis (NADPH + H+)

Question 16

What is the H-carrier redox cycle?

Answer 16

NADP+ and NAD+ going to NADPH + H+ and NADH + H+ by reduction. Then NADPH + H+ oxidises due to biosynthetic reduction.
NADH + H+ oxidises due to ATP synthesis.

Question 17

What happens when there is a high concentration of ATP in the body?

Answer 17

Anabolic pathways are opened to get rid of ATP.

Question 18

What happens when there is a low concentration of ATP and a high concentration of ADP and AMP?

Answer 18

Catabolic pathways are activated to form ATP.

Question 19

What is adenylate kinase used for?

Answer 19

To further help ATP production by:

2ADP -> ATP + AMP

Question 20

What are high energy signals in the body?

Answer 20

ATP
NADH
NADPH
FADH2

Question 21

What are low energy signal in the body?

Answer 21

ADP, AMP
NAD+
NADP+
FAD+

Question 22

What is energy stored as in the body?

Answer 22

Usually as glycogen and triglycerides.

Question 23

What is creatine phosphate?

Answer 23

Creatine phosphate derives from Creatine.
When ATP levels are high creatine is stored as creatine phosphate.
Creatine with the help of ATP is phosphorylated by an enzyme called creatine kinase to form creatine phosphate and ADP.

Question 24

Why is creatine phosphate important?

Answer 24

Because the reverse reaction is possible to form ATP. This means that ATP can be formed anaerobically if needed. A phosphate bond energy is stored in creatine phosphate to be used later on. So in case of rest or intense energy usage creatine and creatine phosphate can be utilised.

Question 25

How does creatinine production work?

Answer 25

There is a spontaneous breakdown of creatine and creatine phosphate into creatinine which occurs at a constant rate.

Question 26

How can levels of creatinine be monitored or measured?

Answer 26

By urine sample.

Question 27

Why is creatinine a useful clinical marker?

Answer 27

Because the rate is usually constant unless anything abnormal has happened the creatinine concentration can be used as a marker for urine dilution.
It also provides a measure of muscle mass in an individual.
Since it is excreted by the kidneys, it can detect kidney failure.
Can be used to estimate true urinary loss of many substances.
A lot of substances and hormones are standardised to creatinine levels.