Proteins

Question 1

Protein make up how much body mass (%)

Answer 1

13 – 15% of body mass

Question 2

What are five Functions of Proteins?

Answer 2

Make-up of Structures:
e.g. collagen, keratin in nails and hair.

Transport of substances across cell membranes

Hormones to allow chemical signals. 

Contraction using muscle fibres.

Enzymes: catalyse cellular reactions

Question 3

What’s the difference between Essential & Non-essential Amino Acids?

Answer 3

Essential
Cannot be synthesised in the body and they must be provided in the diet to maintain balance.

Non-essential amino acids
Can be synthesised in the body from metabolic intermediates by means of transamination as long as there is adequate nutrition.

Question 4

How many amino acids are there?

Answer 4

20 in total

9 Essential
11 Non-Essential

Question 5

At whole body level approximately what is protein turnover?

Answer 5

300g per day

Question 6

Protein turnover rate in tissues
• Muscle % per day?
• Liver % per day?

Answer 6

• Muscle 1.15% per day

* Liver 12.1% per day

Question 7

Protein Requirements

Answer 7

Intake approximately 1.4-2g per kg of body weight

Question 8

How much protein post exercise is necessary

Answer 8

> 20 g high-quality protein post exercise is unnecessary

Question 9

Protein Quality

Answer 9

The biological value (BV) of a protein food is determined by its content of EAAs.

biological value is the proportion of absorbed protein retained in the body.

Question 10

What does DIASS stand for?

Answer 10

Digestible Indispensable Amino Acid Score

Question 11

How many EAA exist in human body and how do you get them?

Answer 11

9 and Food.

Question 12

Where does translation take place?

Answer 12

In the cytosol (ribosomes)

Question 13

What does transfer RNA do?

Answer 13

AAs to ribosomes

Question 14

What are the two groups proteins are composed into?

Answer 14

An amino group and a carboxyl group

Question 15

Nitrogen Balance

Answer 15

• Nitrogen balance exists when nitrogen intake (protein) equals nitrogen excretion

NB=Nt -Nu -Nf -Ns =0

• Nt = total nitrogen intake from food
• Nu = nitrogen in urine
• Nf = nitrogen in faeces
• Ns = nitrogen in sweat

Question 16

Metabolic pathways for amino acids

Answer 16

https://www.youtube.com/watch?v=l0V-Xmps1mE

Question 17

What happens during the process of transamination?

Answer 17

Transfer of one amino group from one molecule to another

Question 18

What does gluconeogenesis mean?

Answer 18

Formation of glucose from non-carbohydrate sources

Question 19

Ammonia is toxic and can be excreted after it has been converted to?

Answer 19

Urea

Question 20

The Urea Cycle

Answer 20

Disposes of excess nitrogen

AAs from protein breakdown form ammonia during the process of deamination.

This is toxic therefore excess nitrogen is excreted as urea in urine.

Approximately 60-90% of nitrogen in urine is in the form of urea.

Urea containing Nitrogen is excreted in urine at a rate of approximately 25-30g per day whilst the rate is higher in individuals with high protein intake.

Question 21

Protein catabolism contributes (%)

Answer 21

Contributes only 2-5% of the body’s energy requirement or approximately 3-6% during prolonged exercise.

Question 22

The glucose-alanine cycle

Answer 22

https://www.youtube.com/watch?v=V9CSKTFyaYw

Question 23

What four steps make up Amino acid metabolism

Answer 23

1. Protein synthesis
2. Converted to other glucose and AAs (transamination)
3. Lipids formation
4. Glycogen formation