Metabolic fuels

Question 1

What is metabolism?

Answer 1

Metabolism refers to the sum of the chemical reactions that take place within each cell of a living organism.
Catalysed by enzymes

Question 2

How are dietary components metabolised?
(4 main pathways)

Answer 2

Biosynthetic
Fuel storage
Oxidative processes
Waste disposal

Question 3

What is anabolic and give the pathways:

Answer 3

Anabolic – synthesise larger molecules from smaller components
Eg. Biosynthetic, fuel storage, waste disposal
Requires energy

Question 4

What is catabolic and give the pathways:

Answer 4

Catabolic – break down larger into smaller
Eg. Oxidative, waste disposal

Question 5

How is energy provided for anabolic processes?

Answer 5

Catabolic reaction of oxidation of carbs, lipids and proteins, produces energy in form of ATP, then used for anabolic processes and becomes ADP + Pi

Question 6

Name the reactants of Kreb’s cycle:

Answer 6

Acetyl CoA
Citrate - 6C
3 NAD+
FAD
ADP

Question 7

Name the products of Kreb’s cycle:

Answer 7

CoA
3 NADH H+
2 CO2
ATP
FADH2

Question 8

What are co factors?

Answer 8

Macronutrients that enzymes require in order to function.
Eg. Thiamine / B1
Needed for acetyl CoA into krebs cycle

Question 9

What is the specialisation of adipose - liver - muscle tissues?

Answer 9

Adipose tissue – 85% fat, storage of energy-rich molecules.
Liver- metabolically active (e.g. Gluconeogenesis, removal of toxins).
Muscle – Activity

Question 10

What are the electron accepting coenyzmes:

Answer 10

NAD+ – NADH+
NADP+ – NADPH
FAD – FADH

Question 11

What happens to the NADH and FADH2 in ETC?

Answer 11

They are oxidsed and this releases energy used to produce ATP.

Question 12

What are the 3 main dietary energy sources?

Answer 12

Carbohydrates
Lipids
Proteins

Question 13

Oxidation equation?

Answer 13

Carb/Lipid/Protein + O2 = ATP + CO2 +H2O

Question 14

What types of carbohydrates are there?

Answer 14

Monosaccharides - glucose, fructose
Disaccharides - sucrose (plant), lactose (milk)
Glycogen is branched

Question 15

Explain the dietary component in proteins:

Answer 15

Amino acids in chains, contain carbon, hydrogen, oxygen & nitrogen
Maintains nitrogen balance - when starving/dieting, there is a decrease in proteins thus decrease in nitrogen and that affects cell functions

Question 16

Explain the dietary component in lipids:

Answer 16

3 fatty acids esterified to one glycerol mostly - most efficient energy source

Question 17

Explain the dietary component in alcohol:

Answer 17

Typically ethanol, highly energetic

Question 18

How is excess energy stored?

Answer 18

Lipid - Stored as triglycerides, approx 15kg
Glucose - Stored as glycogen, approx 200g in liver & 150g in muscle
Protein - Stored as protein, approx 6kg

Question 19

How much is each dietary component per gram?

Answer 19

Carbohydrates - 4kcal/g
Protein - 4kcal/g
Alcohol - 7kcal/g
Lipid 9kcal/g

Question 20

How much is carbs and lipids as ATP production?

Answer 20

Carbs - 30% of ATP production at rest
Lipids - 70% of ATP production at rest
Proteins are often used in longer periods of starvation

Question 21

What is BMR?

Answer 21

Basal Metabolic Rate
Amount of energy needed to keep the body alive in the
rest state.
Energy needed to maintain non exercise bodily functions
eg. respiration, heart muscle contraction, biosynthetic processes, repairing & regenerating tissues, ion gradients across cell membranes.

Question 22

How is BMR measured?

Answer 22

BMR = 1kcal/kg body mass/hr
Adult requires approximately 0.8g/kg ideal body weight protein per day

Question 23

What are the conditions essential for measuring BMR?

Answer 23

• Post-absorptive (12 hour fast)
• Lying still at physical and mental rest
• Thermo-neutral environment (27 – 29C)
• No tea/coffee/nicotine/alcohol in previous 12 hours
• No heavy physical activity previous day
• Establish steady-state (~ 30 minutes)

Question 24

What factors decrease BMR?

Answer 24

• Age, as you get older, BMR decreases,
• Gender, female have lower BMR since they have less metabolically active tissues,
• Dieting/Starvation
• Hypothyroidism, less thyroid hormone = lower BMR
• Decreased muscle mass

Question 25

What factors increase BMR?

Answer 25

• High BMI
• Hyperthyroidism
• Low ambient temperature
• Fever/infection
• Pregnancy, due to increase in weight and thyroid hormone
• Exercise

Question 26

What is malnutrition?

Answer 26

A state of nutrition with a deficiency, excess or imbalance of
energy, protein or other nutrients, causing measurable adverse effects

Adverse effects - Tissue/body (shape, size, composition), body function

Question 27

What are essential nutrients?

Answer 27

Essential amino acids
Essential fatty acids
Vitamins - Vitamin C, Vitamin B12
Minerals

Question 28

What are micro nutrients and what are they important in?

Answer 28

Trace elements and vitamins
- Co-factors in metabolism
- Gene expression
- Structural components
- Antioxidants

Question 29

What is Vitamin C for?

Answer 29

AKA Ascorbic acid, found in fruit and vegetables
For: Collagen synthesis, improve iron absorption, antioxidant

Question 30

What is Vitamin B12 for?

Answer 30

Found in: milk, meat, eggs
For: Protein synthesis, DNA synthesis, regenerate folate (and therefore – cell division), fatty acid synthesis, energy production