Protein

Question 1

Why are they called essential amino acids (EAA)?

Answer 1

They cannot be synthesised by the body - they can only be consumed via food

Question 2

What are conditionally non-essential amino acids?

Answer 2

They are not always non-essential, for example:
Arginine - liver disease needs higher levels for ammonia
Another example, pregnancy, fluctuations in hormones can draw upon other non-essential

Question 3

Proteins provide …………… to all …………… in the human body.

Answer 3

Structure, cells

Question 4

Many proteins are …………. that increase the rate of …………… reactions

Answer 4

Enzymes, metabolic

Question 5

what do amino acids have a central role in?

Answer 5

Metabolism of many organs and tissues

Question 6

Amino acids are the building blocks/ precursors for the ………………….

Answer 6

Synthesis of body proteins

Question 7

Amino acids are precursors and regulators of the synthesis of …………… (4)

Answer 7

Neurotransmitters, hormones, DNA and RNA

Question 8

When understanding whole body protein balance, what are the areas where protein is excreted?

Answer 8

Faeces
Urine
Smaller contributions by sweat, hair and skin
Measured by nitrogen content in the faeces and urine

Question 9

Explain the roles of the liver surrounding proteins.

Answer 9

Major site of protein synthesis, production of new proteins
Role in metabolising amino acids and ensuring the by-products of amino acid metabolism e.g. ammonia can be converted to urea and removed in the form of urine.

Question 10

Skeletal muscle function surrounding protein

Answer 10

Peripheral tissue which takes up a large proportion of amino acids that have been broken down and circulated in the body.

Question 11

What element are amino acids a source of?

Answer 11

Nitrogen

Question 12

Protein consumption recommendation are typically formed based on what?

Answer 12

Whole body nitrogen balance

Question 13

Loss of body nitrogen suggests what?

Answer 13

Tissues, organs, the heart are losing proteins which can increase the risk of many diseases and conditions with varying outcomes.

Question 14

Describe the structure of an amino acid

Answer 14

Carboxyl group (COOH), amino group (NHH) and an amino side change (R group) interchangeable from protein to protein

Question 15

What is the R group?

Answer 15

A series of linked atoms that are often branched together linearly like a chain. The structure and length of the side chain is unique to each specific protein.

Question 16

1 gram of nitrogen is equivalent to how much protein?

Answer 16

6.25g protein

Question 17

Nitrogen (protein) balance (whole body), explain what is meant by balanced, positive balance and negative balance?

Answer 17

Balanced: Protein in = Protein out
Positive: Protein in > Protein out
Negative: Protein in < Protein out

Question 18

How would you calculate someone’s whole body nitrogen balance?

Answer 18

Determine nitrogen excretion (e.g. urine, faeces, sweat in grams over 24hr period)
Determine nitrogen intake (protein intake in grams divided by 6.25
N balance = Intake - excretion values

Question 19

What is protein reference nutrient intake (RNI)?

Answer 19

0.75 g/kg/day
This is the value that is set to ensure whole body nitrogen levels are balanced.

Question 20

What is the estimated average requirement (EAR) for protein intake and explain how it helped determine the RNI value?

Answer 20

EAR = 0.6 g/kg/day - over half the population could consume this quantity to maintain nitrogen balance based on research.
RNI = EAR plus 2 standard deviations producing a value of 0.75 - will be sufficient for 97 % of a population

Question 21

Do values typically exceed the RNI value? T or F

Answer 21

T

Question 22

Limitations of Nitrogen balance

Answer 22

No information of tissues
Lack of sensitivity; only a gross measure of intake and excretion
Zero balance on low intake may reflect accommodation (similar to low EA concept)
Positive balance may not relate to lean body mass

Question 23

Main purpose of understanding someone’s nitrogen balance

Answer 23

It is an adequate method to measure if someone is amino acid deficient

It is inadequate for estimating AA requirements for those partaking in exercise

Question 24

Simplified movement of proteins through the body.

Answer 24

Dietary protein is ingested
Passes through the stomach and intestines and is digested; broken down into amino acids
Amino acids are taken up by the liver and undergoes protein synthesis where proteins are made. As well as, production of pyruvate which is the first stage of gluconeogenesis (production of glucose from non-CHO sources). It also releases AA’s back into circulation for other tissues e.g. muscle.
AA’s are synthesised in the skeletal muscle and produce new muscle proteins.

Question 25

What is meant by the term endogenous?

Answer 25

Mean that they are made within the body - Endogenous Amino acids are made without the need of dietary proteins.

Question 26

What is the intracellular amino acid pool?

Answer 26

A pool of amino acid found within the cell whereby synthesis of proteins will stem from and products of protein breakdown will end up before entering the blood stream.

Question 27

How is muscle protein gained? And when is it lost?

Answer 27

Protein synthesis is greater than protein breakdown - muscle is gained Protein synthesis is less than protein breakdown - muscle is lost

Question 28

What happens to MPS and MPB after a meal?

Answer 28

Spike in MPS and a very modest drop in MPB. Once digested, MPS drops and there is a modest incline in MPB, until the next meal is consumed.

Question 29

Higher protein diets cause a decline in kidney and liver function? T or F

Answer 29

F

Question 30

Higher protein diets cause bone loss? T or F

Answer 30

F - no evidence to prove this statement, some research suggests there is a slight benefit to above average protein consumption.

Question 31

When protein consumption is paired with an exercising individual what can be said for MPS and MPB?

Answer 31

Spend a greater proportion of the day in a net positive protein synthesis state (protein accretion)

Question 32

What are the results of rest, rest+AA, Resistance ex. (RE) and RE+AA on MPS and MPB?

Answer 32

At rest: Overall, MPB. At rest+AA: Increased levels of MPS RE: Slightly negative overall RE+AA: Increased levels of MPS even greater than rest+AA

Question 33

What is the protein turnover rate per day (%)?

Answer 33

1-2% per day

Question 34

How long would it take for a complete renewal of body protein?

Answer 34

3-4 months, roughly 300-600g of muscle protein per day

Question 35

What area of the body has the largest protein pool?

Answer 35

Myofibrillar proteins - however also takes the longest to be resynthesized and renewed.

Question 36

What area of the body has the lowest protein pool?

Answer 36

Mitochondrial proteins: however has the quickest rates of turn over.

Question 37

What is the impact of endurance and resistance exercise on synthesis of myofibrillar proteins?

Answer 37

Resistance training causes myofibrillar protein synthesis to double compared to endurance training

Question 38

What is the impact of endurance and resistance exercise on synthesis of mitochondrial proteins?

Answer 38

Endurance training increases mitochondrial protein synthesis more than resistance. However, resistance training still does show a change in rates just not to the same extent.

Question 39

Is the RNI value tailored to athletes?

Answer 39

NO - 0.75 g/kg/d is the value to avoid nitrogen deficiency. Therefore, athletes will require more protein.

Question 40

What are the benefits for athletes to consume more than the recommended RNI?

Answer 40

1. Repair, replace and remodel damaged proteins (e.g. muscle) 2. Optimal function of metabolic pathways using AA's 3. Support lean tissue maintenance and accretion 4. Support optimal function of the immune system

Question 41

Explain the anabolic feeding window for protein?

Answer 41

Exercise stimulates a prolonged elevation of muscle protein synthesis (MPS), this effect can last for 24 hrs, even 48 hrs after exercise. The greatest synergistic effect is within 3 hrs post exercise.

Question 42

How much protein is required post exercise?

Answer 42

0.24 g/kg (0.18 - 0.3) is the recommended dosage for an individual optimising protein consumption

Question 43

What is the daily recommended dosage for a strength/power athlete?

Answer 43

1.6 g/kg/d

Question 44

What is the optimal amount of protein consumption after a single bout of exercise?

Answer 44

Ingestion of 30g protein is sufficient to maximise MPS rates during recovery from a single bout of endurance exercise