Module 6 - Energy Metabolism Part 1

Question 1

What is energy metabolism

Answer 1

It is reactions where the body obtains and expands energy from food

Question 2

What are coupled reactions

Answer 2

Reactions that require energy in order to produce energy

Question 3

What kinds of energy are used in the body

B) what are the main fuels that cells use for energy production

Answer 3

Energy: heat (body temp), mechanical (muscles), electrical (nerves) and chemical (digestion)
Fuels: glucose, fatty acids, amino acids

Question 4

Where do the citric acid cycle and electron transport chain take place in the mitochondrion

Answer 4

Citric acid cycle: inner compartment

Electron transport chain: inner membrane

Question 5

Process of fats being stored as fats

Answer 5

Chilomicrons and VLDL loaded with TG. Then, lipoprotein lipase hydrolyses TG, releasing FA to enter adipose cells. There they are reassembled into TG in adipose tissue

Question 6

How to use fat for energy. What percentage of energy comes from fats

Answer 6

Hormone sensitive lipase release FA and glycerol.

60% of the body’s energy needs at rest

Question 7

Anabolism versus catabolism

Answer 7

Anabolism: uses energy to build compound
Catabolism: breaks compounds and releases energy

Question 8

What percentage of energy comes from proteins

Answer 8

10% of energy. Amino acids can also be transformed and stored as fat

Question 9

what is gluconeogenesis

Answer 9

Making glucose from non-carbohydrate sources such as amino acids or glycerol. In fact, in the absence of glucose, body proteins lose their nitrogen’s and are broken down to make glucose

Question 10

What is ATP

Answer 10

High energy compound that powers all activities in living cells. Bonds of phosphate groups contain a lot of energy and when they are broken, energy is released

Question 11

When the body converts food energy to be used by cells, how much energy is lost to heat

Answer 11

Half the energy is lost as heat

Question 12

What is the Thermic effect of food?

How much energy does this represent for a diet

Answer 12

It’s the energy required for digestion, absorption and disposal of ingested nutrients
- 10% of energy for a mixed diet

Question 13

Can fatty acids be converted into pyruvate?

Answer 13

No they can also be converted into acetyl-CoA. Glycerol can be converted to pyruvate though

Question 14

What is pyruvate. Can it make glucose?

Answer 14

A 3-Carbon compound that plays a key role in energy metabolism
Pyruvate can also be used to make glucose

Question 15

What is acetyl CoA. Can it be used to make glucose?

Answer 15

A 2 Carbon compound to which a molecule of CoA is attached (made from B vitamin pantothenic acid)
Cannot be used to make glucose

Question 16

What is the TCA cycle

Answer 16

A series of metabolic reactions that breaks down molecules of acetyl CoA to CO2 and H

Question 17

Which complexes help metabolic reactions happen

Answer 17

Enzymes (remain unchanged) and coenzymes (required for enzymes to function, b vitamins are great coenzymes)

Question 18

Goal of electron transport chain

Answer 18

Transports electrons from hydrogen to oxygen, captures about half the energy released by breaking C-C bonds and storing it in high energy bonds of ATP.

Question 19

Is glucose to pyruvate a reversible reaction

Answer 19

Yes. It can be converted back to glucose with the help of the liver

Question 20

What is the goal of glycolysis

Answer 20

Splitting glucose for energy. Yields two 3 carbon molecules which get converted to pyruvate

Question 21

What are the differences between the aerobic and anaerobic pathways of pyruvate once it’s formed

Answer 21

Anaerobic: quick energy needs. Pyruvate is converted to lactate without oxygen for short duration of high- intensity exercise and energy needs
Aerobic: slower energy needs. Pyruvate is converted to acetyl CoA

Question 22

Under what circumstances would pyruvate to lactate happen

Answer 22

In absence of sufficient oxygen in the mitochondria, pyruvate can accept hydrogens which will turn it to lactic acid. This produces ATP quickly anaerobically for short durations

Question 23

What is the cori cycle

Answer 23

When lactate from muscles is reconverted to glucose in the liver

Question 24

Explain the pyruvate to Acetyl CoA system

Answer 24

It is slower, longer and uses oxygen, pyruvate enters the mitochondria and carbons are removed producing CO2 and then the 2 carbon compound joins CO2 to form acetyl CoA which is irreversible

Question 25

Pyruvate can be used to make which compounds (directly)

Answer 25

Glucose, acetyl CoA, lactate and amino acids

Question 26

Which amino acids (ketogenic and glucogenic) are used to make pyruvate vs acetyl CoA

Answer 26

Ketogenic can be used to make acetyl CoA (therefore can’t make glucose) and glucogenic can make pyruvate (and therefore glucose)

Question 27

Glycerol can be used to make which compounds (2)

Answer 27

Glucose and pyruvate

Question 28

What is the process of fatty acid oxydation

Answer 28

Fatty acids are taken apart 2 carbon fragments at a time and then they form acetyl CoA. As this occurs, hydrogens and electrons are released and carried to the electron transport chain

Question 29

How to fatty acids lose their carbons to become acetyl CoA

Answer 29

A fatty acid is first activated by CoA. As each carbon-carbon bond is broken, hydrogens and electrons are released and picked up by coenzymes. Then another CoA joins the chain and the beta carbon weakens and acetyl CoA slips off leaving a fatty acid that is two carbons shorter

Question 30

What is the first step for amino acid coming into energy metabolism

Answer 30

They must be deaminated

Question 31

What are the entry points of amino acids to energy pathways

Answer 31

It can be converted to pyruvate (glucogenic), or converted to acetyl CoA (ketogenic) or it can enter the TCA cycle directly (glucogenic)

Question 32

What is an example of an amino acid that is both ketogenic and glucogenic

Answer 32

Tryptophan

Question 33

What is the starting molecule of the TCA cycle

Answer 33

Oxaloacetate

Question 34

Which molecule does not yield both glucose and amino acids

Answer 34

Fatty acids

Question 35

Which macromolecule provides the most energy per gram

Answer 35

Fat because it has the most carbon hydrogen bonds