Module 2.1- Energy Metabolism

Question 1

What are the three kinds of fuels an animal body demands?

Answer 1

Amino Acids (protein), fatty acids (fats and acids) and glucose (carbohydrates)

Question 2

Why do animal bodies require fuel?

Answer 2

For Homeostasis (the maintenance of the body) and because they are building blocks for growth and reproduction.

Question 3

Is it likely that the supply of fuel matches the demand for it in an animals body?

Answer 3

Highly unlikely.

Question 4

How does the animal body cope with the differences between supply and demand for fuels?

Answer 4

Energy (fuel) metabolism. The endocrine and homeostasis systems of the body assist in maintaining constant energy supply, dealing with excess and shortcomings in energy intake

Question 5

Which body systems assist in maintaining the supply of energy needed by the body?

Answer 5

Endocrine and Homeostasis

Question 6

What is anabolism?

Answer 6

Building up of tissues

Question 7

What is catabolism?

Answer 7

Breaking down of tissues

Question 8

What are the two steps of catabolism?

Answer 8

Hydrolysis of larger organic molecules (similar to what happens in the digestive tract) followed by oxidation of the smaller molecules to release energy for ATP production

Question 9

What regulates metabolic function?

Answer 9

Substrate concentration
Enzyme activity
Enzyme concentration
Compartmentation (eg. glycolysis=cytosol, Krebs cycle=mitochondrial matrix)

Question 10

Outline Carbohydrate (glucose) conversion as part of energy metabolism?

Answer 10

Carbohydrate compound is oxidised generating energy, CO2 and H2O and substrates for other metabolic reactions. Converted into Glycogen which can be readily stored and retrieved for conversion into ATP.

Question 11

What is ATP?

Answer 11

adenosine triphosphate, the chemical compound which the body can use as energy.

Question 12

What is Glycogen?

Answer 12

A product of the biochemical pathway of conversion of carbohydrate (glucose) into useable energy. Can be readily stored and retrieved.

Question 13

How are Amino Acids transported in the body?

Answer 13

In the blood

Question 14

What are Amino Acids used for?

Answer 14

Protein synthesis

Question 15

Outline the chemical process of the conversion of Amino Acids to useable energy

Answer 15

Catabolised via Proteolysis

Amino acid (in blood) -> Protein (in cell, readily stored and retrieved in cell) -> CO2 + H2O + NH3 + energy (in cell)

2 NH3 then converted into urea in the liver.

Question 16

How are Amino Acids stored in cells?

Answer 16

Converted via Proteolysis into proteins to be stored in the cell

Question 17

Outline the chemical process of fat metabolism

Answer 17

Fats (triglycerides) broken down by lipoprotein lipase. Fatty acids are taken up by the liver (glycerol -> liver). Fatty acids are oxidised for energy + H2O + CO2.

Unused glycerol is combined with fatty acids and stored as fat droplets until they are ready to be released back into the blood

Question 18

What happens when biomolecules exist in excess in the body?

Answer 18

They are stored as storage molecules (glycogen, triglycerides)

Question 19

What can biomolecules be used for?

Answer 19

Synthesis of other molecules

Question 20

What is released when molecules are broken down?

Answer 20

Energy is released

Question 21

What is metabolic rate?

Answer 21

The rate at which energy is expended during internal and external work.

Question 22

What is energy balance?

Answer 22

Energy input - energy output (heat + work)

Question 23

What are some things that cause an animal to have a higher energy output than usual?

Answer 23

Growth, reproduction, lactation

Question 24

What is the measurement for metabolic rate?

Answer 24

Kilojoules per hour (kJ/h)

Question 25

How is metabolic rate often expressed?

Answer 25

The rate of heat production

Question 26

What is metabolic rate influenced by?

Answer 26

Muscular activity, age, gender, size (body surface area), environmental temperature

Question 27

What is basal metabolic rate (BMR)?

Answer 27

An animals resting metabolic rate

Question 28

How is basal metabolic rate estimated?

Answer 28

By measuring oxygen consumption over time (Volume of O2 in ml per minute)

Question 29

Why is basal metabolic rate estimated using the rate of oxygen consumption over time?

Answer 29

Because oxygen consumption correlates with the rate at which nutrients are being oxidised and thus correlates with the rate of heat and energy production

Question 30

What is basal metabolic rate often scaled by?

Answer 30

Body mass

Question 31

Why do we need to scale basal metabolic rate by body mass?

Answer 31

Because metabolic rate is proportional to body weight and body surface area. Scaling it by body mass allows for expression of metabolic level independent of these factors, allowing cross species comparison.

Question 32

Does a horse produce more heat per day than a rat? Explain your answer

Answer 32

Yes, bigger homeotherms produce more heat per day than smaller homeotherms. Metabolic rate is positively correlated to body size

Question 33

Is metabolic rate positively (increases as body size increases) or negatively (decreases as body size increases) correlated to body size?

Answer 33

Positively

Question 34

Does a horse produce more heat per day per kilogram than a rat? Explain your answer.

Answer 34

No, the horse has a lower rate of heat production per unit of body weight than that of a rat. Metabolic rate per unit of body weight is negatively correlated to body size

Question 35

Is metabolic rate per unit of body mass positively (increases as body size increases) or negatively (decreases as body size increases) correlated to body size?

Answer 35

Negatively

Question 36

As mass increases what also increases?

Answer 36

Metabolic rate

Question 37

What are the three states of energy balance?

Answer 37

positive, neutral and negative

Question 38

What is the state of positive energy balance?

Answer 38

Energy input > (more than) Energy output

Question 39

What is the state of negative energy balance?

Answer 39

Energy input < (less than( energy output

Question 40

What is the state of neutral energy balance?

Answer 40

Energy input = energy output

Question 41

What is the absorptive state?

Answer 41

Anabolic metabolism | When nutrients are being absorbed after consumption

Question 42

What is post-absorptive state?

Answer 42

Catabolic metabolism | Fasting, when no nutrients are being absorbed. The time between feeding.

Question 43

Which of the three forms of energy storage are limited and which are (virtually) unlimited in their ability to store energy in this form?

Answer 43

``` Fat = unlimited Proteins = limited Glycogen = limited ```

Question 44

In which state (absorptive or post-absorptive) does energy storage occur?

Answer 44

Absorptive state

Question 45

In which state (absorptive or post-absorptive) does conversion of stored macromolecules into energy occur?

Answer 45

Post-absorptive

Question 46

What does glycogenesis convert, and into what?

Answer 46

Glucose -> glycogen

Question 47

What does glycogenolysis convert, and into what?

Answer 47

Glycogen -> glucose

Question 48

What does gluconeogenesis convert, and into what?

Answer 48

Amino acids -> glucose

Question 49

What does protein synthesis convert, and into what?

Answer 49

Amino acids -> protein

Question 50

What does protein degradation convert, and into what?

Answer 50

Proteins -> amino acids

Question 51

What does fat synthesis (lipogenesis of triglyceride synthesis) convert, and into what?

Answer 51

Fatty acid and glycerol -> Triglycerides

Question 52

What does fat breakdown (lypolysis or triglyceride degradation) convert, and into what?

Answer 52

Triglycerides -> Fatty acids and glycerol

Question 53

What does glycogenesis (Glucose -> glycogen) do to blood glucose levels?

Answer 53

Decreases it

Question 54

What does glycogenolysis (Glycogen -> glucose) do to blood glucose levels?

Answer 54

Increases it

Question 55

What does gluconeogenesis (Amino acids -> glucose) do to blood glucose levels?

Answer 55

Increases it

Question 56

What does protein synthesis (Amino acids -> protein) do to blood amino acid levels?

Answer 56

Decreases them

Question 57

What does protein degradation (Proteins -> amino acids) do to blood amino acid levels?

Answer 57

Increases them

Question 58

What does fat synthesis (lipogenesis of triglyceride synthesis) (Fatty acid and glycerol -> Triglycerides) do to blood fatty acid levels?

Answer 58

Decreases them

Question 59

What does fat breakdown (lypolysis or triglyceride degradation) (Triglycerides -> Fatty acids and glycerol) do to blood fatty acid levels?

Answer 59

Increases them