Lecture 22: ENERGY BALANCE IN CELLS AND ORGANISMS

Question 1

What is in the first law of thermodynamics?

Answer 1

The total energy within a system is constant, energy can neither be created or destroyed, energy can be converted and biology relies on energy conversions

Question 2

Where does energy first come from?

Answer 2

The sun

Question 3

Where does energy from the sun go?

Answer 3

To plants for photosynthesis

Question 4

What is released from photosynthesis?

Answer 4

Oxygen

Question 5

What is oxygen used for?

Answer 5

Respiration

Question 6

What is the result of respiration?

Answer 6

Energy to use in anabolism, movement and transport

Question 7

What is the result of using energy?

Answer 7

Heat, carbon dioxide and water

Question 8

What goes into the body?

Answer 8

Food and oxygen

Question 9

What is within food?

Answer 9

Chemical energy (carbohydrates, fats and proteins) and nutrients (vitamins and minerals)

Question 10

What is food digested to?

Answer 10

Glucose, fatty acids, proteins, vitamins and minerals

Question 11

What is there a balance between in the body?

Answer 11

Storage and metabolism

Question 12

What is stored?

Answer 12

Triacylglycerol (TAG’s) and glycogen

Question 13

What is involved in metabolism?

Answer 13

Glycolysis, beta oxidation and the citric acid cycle

Question 14

What comes out of the body?

Answer 14

Heat, carbon dioxide and water

Question 15

What happens in anabolism?

Answer 15

ATP is broke down into ADP and Pi when doing cellular work (high energy phosphate bond is broken by hydrolysis)

Question 16

What happens in catabolism?

Answer 16

ADP and Pi combine to make ATP using energy from food

Question 17

what happens in metabolism?

Answer 17

Carbon compounds in food are oxidised to form ATP

Question 18

What is the energy balance in the body (perfect)?

Answer 18

Energy intake (food) = energy expended (basal metabolism and activities)

Question 19

What is the energy balance in reality?

Answer 19

Energy intake = energy expended + energy stored

Question 20

What is energy stored?

Answer 20

Weight gain

Question 21

What can weight loss be achieved by?

Answer 21

Reducing energy intake (eat less and/or take certain drugs), increasing activities and increase basal metabolism

Question 22

What is basal metabolism?

Answer 22

Energy required for maintenance of life

Question 23

What is leptin?

Answer 23

A hormone which helps control appetite and weight

Question 24

What are the units of energy?

Answer 24

Joules (J)

Question 25

What is 1 joule?

Answer 25

The energy required to push against 1 newton of force for 1 metre

Question 26

What is 1 cal?

Answer 26

4.184J

Question 27

What is 1 Cal?

Answer 27

4.184kJ

Question 28

What is daily dietary intake and energy expenditure usually measured in?

Answer 28

MJ

Question 29

How is energy content of food measured?

Answer 29

Using calorimetry

Question 30

What is the Atwater factor of fat?

Answer 30

38kJ/g

Question 31

What is the Atwater factor of carbohydrate?

Answer 31

17 kJ/g

Question 32

What is the Atwater factor of protein?

Answer 32

17 kJ/g

Question 33

What is the Atwater factor of ethanol?

Answer 33

29kJ/g

Question 34

Why is not all the energy in food available?

Answer 34

Losses I faces - fibre (cellulose), nitrogen is not oxidised (excreted in urine) so we have to adjust for these factors

Question 35

What does direct calorimetry rely on?

Answer 35

Measuring heat output from an individual

Question 36

What is direct calorimetry good for determining?

Answer 36

Basal metabolic rate (BMR)

Question 37

What is indirect calorimetry based on?

Answer 37

Oxygen consumption and carbon dioxide production measured using a respirometer.

Question 38

What is associated with every litre of oxygen consumed?

Answer 38

A certain amount of energy (20.9 kJ)

Question 39

What does indirect calorimetry allow to be calculated?

Answer 39

Energy expenditure for a range of activities and the respiration exchange ratio (RER)

Question 40

What is the RER formula?

Answer 40

RER=carbon dioxide produced/oxygen consumed

Question 41

What can RER determine?

Answer 41

What fuel is being used

Question 42

What is involved in maintenance of life?

Answer 42

Muscle contractions, nerve conduction, ion transport, synthesis of macromolecules and maintenance of body heat

Question 43

What is basal metabolic rate usually defined as?

Answer 43

Energy expenditure at rest

Question 44

What factors affect BMR?

Answer 44

Gender, age, body size and composition, genetics, hormonal status, stress levels, disease status and certain drugs

Question 45

What is BMR increased by?

Answer 45

Athletic training, late stages of pregnancy, fever, drugs (caffeine) and hyperthyroidism

Question 46

What is BMR decreased by?

Answer 46

Malnutrition, sleep, drugs (beta blockers) and hypothyroidism

Question 47

What is the RER value for sugar?

Answer 47

1

Question 48

What is the RER value for fats?

Answer 48

0.7