Energy & Metabolism 3

Question 1

how many KJ = 1 calorie?

Answer 1

1 calorie = 4.18 KJ so..
calories x 4.18 = kilojoules
kilojoules / 4.18 = calories

Question 2

define metabolism

Answer 2

all of the chemical reactions occurring in the body

Question 3

how much energy does the brain & muscles use?

Answer 3

Brain uses 22% of energy

Muscles use 22% of energy

Question 4

Define metabolic rate

Answer 4

rate of energy output by the body

Question 5

Define resting metabolic rate (RMR)

Answer 5

• “energy cost at rest”

to keep you alive

Question 6

What is the Basal metabolic rate (BMR)

Answer 6

• standardised measure of resting metabolic rate

- individual is fasted, rested & inactive but awake

Question 7

What is the total metabolic rate (TMR)

Answer 7

BMR/RMR + energy output from physical activity

Question 8

What is the basal metabolic rate determined by?

Answer 8

• weight
• height
• surface area
• age
• gender
• muscle mass
• hormones
• pregnancy
• lactation

Question 9

how do you measure metabolism

Answer 9

• direct calorimetry - uses a calorimetric chamber, measures heat output.
• indirect calorimetry - measures oxygen use/ gas exchange

Question 10

What is energy input?

Answer 10

• estimated energy requirement (EER)
• the body derives energy from breakdown of nutrients
• the potential energy value of foods is given in KJ or Cal

Question 11

What are catabolic reactions?

Answer 11

• exothermic reactions

- energy transferred to an energy carrying molecule ATP & heat

Question 12

What are anabolic reactions?

Answer 12

• endothermic reactions
• require energy in the body in the form of ATP
• builds small molecules into larger ones

Question 13

What are catabolic pathways?

Answer 13

• breakdown complex molecules to simpler ones
• exothermic release energy as heat & ATP
  eg: cellular respiration

Question 14

What are anabolic pathways?

Answer 14

• build up complex molecules of life
• endothermic require energy input in the form of ATP
  eg: biosynthetic reactions

Question 15

How does ATP effect chemical reactions?

Answer 15

it is the only form of energy that can be used to power cell activity

Question 16

Explain creatine phosphate

Answer 16

• like ATP - an energy rich molecule but cant be used directly
• used to quickly convert ADP to ATP by direct phosphate group

Question 17

Glucose can be obtained from…

Answer 17

• Free blood glucose (after a meal)
• Glycogenolysis: breakdown of glycogen stores in muscle and liver
• Glucneogenesis: formation of glucose from other nutrients in the liver

Question 18

Three linked metabolic pathways involved are:

Answer 18

1. Glycolysis
2. Krebs cycle
3. Electron transport chain

Question 19

Explain glycolysis

Answer 19

• Glucose is broken down to 2 pyruvic acid molecules in the cytoplasm
• net gain of 2 ATP

Question 20

Explain Kreb’s cycle

Answer 20

• occurs in the mitochondria
  For each Acetyl-CoA entering krebs cycle:
• carbon atoms are removed as CO2 waste
• 1 ATP made by direct phosphorylation
• 3 NAD+ reduced to 3 NADH + H+
• another carrier FAD is reduced to 1 FADH2

Question 21

What are NAD & FAD

Answer 21

• glycolysis and kreb’s cycle include ‘redox’ reactions

- oxidation = removal of hydrogen & high energy electrons

Question 22

What is the electron transport chain

Answer 22

• NADH + H+ & FADH2 pass on their hydrogens & high energy electron to oxygen as the final ‘acceptor’
• linked to ATP production

Question 23

Explain that catabolism of fat

Answer 23

1. glycerol component converted to pyruvic acid & carries onto kreb’s cycle & ETC
2. fragments are split off thru a series of enzymatic reactions called beta-ovidation in the mitochondria

Question 24

Explain the catabolism of protein

Answer 24

• used when other source are unavailable eg: starvation or during prolonged exercise
• in the liver the amine group is removed
• remaining molecules are converted to pyruvic acid

Question 25

explain anaerobic glycolysis

Answer 25

• not dependant on oxygen

- can only use glucose

Question 26

explain the oxidative system (aerobic)

Answer 26

• dependant on oxygen
• use glucose or fats
• more efficient ATP production