Lecture 4 Proteins

Question 1

Muscles, skin, and hair are mainly composed of

Answer 1

proteins

Question 2

Many proteins are ______ that increase the rate of metabolic reactions

Answer 2

enzymes

Question 3

The muscles contain the largest proportion of protein in a human body (about 40%). The most abundant amino acids are the three branched-chain amino acids (______) names, l______, v______, i________________

Answer 3

BCAAs

leucine, valine, isolecine

Question 4

what are the building blocks of all proteins?

Answer 4

proteins

Question 5

What on the chemical structure of a protein distinguishes the difference in proteins?

Answer 5

R group

Question 6

Protein Turnover:

Answer 6

is the simultaneous synthesis and degradation of protein in the body

amino acids are constantly incorporated into proteins (protein synthesis), and proteins are constantly broken down (protein breakdown) to amino acids.

Question 7

T or F

Different proteins are synthesized and degraded at different rates.

Answer 7

T

Question 8

Generally which proteins have a rapid rate of turnover, and which do not?

Answer 8

proteins that act as enzymes, or hormones have a relatively rapid rate of turnover

structural proteins, such as collagen, and contractile proteins (actin and myosin) have a relatively slow turnover

Question 9

What is the amino acid pool meant for?

Answer 9

protein synthesis. When proteins depredate the amino acids go back to the protein pool.

Question 10

If your body want to make a protein and does not have an AA it needs, the body will either___________ protein synthesis if the AA it needs is essential, until it receives it from the diet, or if it is a non-essential AA then the body will ________ a protein not being used to get that AA it needs

Answer 10

stop

degradate through a process called transamination

Question 11

Protein as fuel for exercise

how much does protein contribute to energy expenditure in resting conditions and exercise

Answer 11

15% resting

5% exercise

Question 12

During very prolonged exercise, when carbohydrate availability becomes limited, _____ _____ ______ (mostly BCAAs) may increase somewhat to ___________

Answer 12

amino acid oxidation

10%

Question 13

The effect of resistance exercise on rates of protein synthesis and degradation

In the hours after exercise both _____ _______ and _______ are increased

Without sufficient amino acid (protein) intake, what will happen?

during exercise, protein synthesis is increased more than breakdown but will exceed protein degradation only when?

Both starvation and immobilization (muscle disuse) result in:

Answer 13

protein synthesis

breakdown

net muscle protein gain will not occur

only after feeding a source of amino acids

muscle atrophy and weakness

Question 14

Resistance training alone results in muscle protein synthesis for at least ________ ______ and muscle protein breakdown for _____ ______

Resistance exercise essentially primes the muscle to have an increased

Answer 14

48 hours

24 hours

muscle protein synthesis response

Question 15

According to the diagram, what happens to the curve when there is a training stimulus

Answer 15

increased protein synthesis and net protein gains occur

Question 16

T or F

A goal for athletes is to remain in a nitrogen-balanced state

Answer 16

T

Question 17

Protein intake

Recommendation protein intake varies worldwide between:

Answer 17

0.8-1.2g/kg body weight

Question 18

Unlike carbohydrate and fat, protein has generally :

Answer 18

not been associated with negative health effects

Question 19

T or F

If are in excess in any Macronutrient, your body will store it as fat

Answer 19

T

Question 20

For athletes, the recommendation of protein intake is approximately double that of non athletes, with a typical range of

Answer 20

1.2 to 2.0g/kg body weight

Question 21

Strength athletes protein intake:

endurance athletes protein intake:

Answer 21

1.6-1.7g/kg body weight

1.2-1.8g/kg body weight

Question 22

T or F

Most athletes reach their required protein intake because with increasing food intake, the intake of protein increases linearly because many food products contain at least some protein

Answer 22

T

Question 23

what is the main determinant of muscle strength and power

Answer 23

muscle size, cross-sectional area

Question 24

What are the 5 factors affecting muscle tissue protein accretion following resistance training?

Answer 24

Amount of protein ingested
Time
Type
Leicine content
Coingestion of carbohydrate

Question 25

Amount of protein ingested

Athletes:

Nonathletes:

Answer 25

Most athletes will be okay with 1.2-2.0g/kg body weight

Most nonathletes will be okay with 0.8 g/kg body weight

Question 26

Time of Protein Ingested

The scientific consensus now:

Answer 26

Is that it is optimal to ingest protein immediately after a bout of resistance exercise

Question 27

Type of Protein Ingested

Proteins can be _____ or ______

Proteins that are rapidly digested and absorbed are _____ and ______. They induce a larger more transient rise in _______________ and ______ ______ _________________________ than casein.

Answer 27

fast, slow

Whey and Soy

aminoacidemia and

muscle protein synthesis

Question 28

Whole body protein synthesis is stimulated more with :

Whole body protein breakdown is suppressed with:

Answer 28

whey

caesin

Question 29

Muscle protein synthesis was found to be greater with: both at rest and following resistance exercise

Answer 29

whey protein

Question 30

Protein quality:

The two common methods for determining protein quality are
1.
2.

Answer 30

calculating the proportion of nitrogen retained (the greater the nitrogen proportion retained, the greater the protein utilization and, therefore, the higher the protein quality

comparing the protein against egg protein (albumin), which is known to have a near perfect distribution of essential amino acids.

Question 31

Explain why leucine content of protein ingested is important

Leucine stimulates the mechanistic target of ______ _______ (m-TORC1), a key ________ protein, and triggers a rise in ______ ______ ______

Therefore, ingested proteins with a high leucine content are most advantageous

The leucine threshold amount to trigger stimulation of muscle protein synthesis is ________ per meal

Answer 31

Leucine acts as a signalling molecule to stimulate translation-initiation pathways, resulting in increased rates of protein synthesis. Leucine is the only AA that does this

rapamycin complex-1

signalling

muscle protein synthesis

3g

Question 32

Coingestion of carbs

Answer 32

Carbohydrate plus protein is more effective in stimulating muscle protein synthesis than protein or carbohydrate alone due to an insulin-mediated increase in amino acid uptake. However, this is only important if protein amount is less than 20g. Ig sufficient protein is ingested, adding carbohydrate has no effect

Question 33

Summary: Optimizing Muscle Protein Gain

1. recommended to ingest high-quality protein ________g or _______g/kg body weight, with 8-10g essential AA and at least _______ leucine at regular 3-4 hour intervals
2. Proteins that are ________ digested and absorbed (ex. _____ ______) are most effective at generating increase in ______ _______
3. Ingesting larger does of protein (____g/kg body wight) before bedtime appears to augment both acute and _________ MPS and skeletal muscle adaptations

Answer 33

20-25g

0.4g/kg body weight

3g

rapidly

Whey Protein

protein synthesis

0.6g/kg body weight

overnight

Question 34

Excessive protein intakes can cause ________, kidney damage and athletes consuming high protein diet should therefore increase their ________ intake ti prevent dehydration

Answer 34

dehydration

fluid

Question 35

Who may be at risk of Insufficient Protein Intake

Answer 35

vegetarian athletes may also be at risk because plant food sources typically contain lower-quality proteins which often contain low levels of essential amino acids; also the digestibility of plant protein can be low