Lecture 4 Proteins Flashcards
Muscles, skin, and hair are mainly composed of
proteins
Many proteins are ______ that increase the rate of metabolic reactions
enzymes
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________________
BCAAs
leucine, valine, isolecine
what are the building blocks of all proteins?
proteins
What on the chemical structure of a protein distinguishes the difference in proteins?
R group
Protein Turnover:
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.
T or F
Different proteins are synthesized and degraded at different rates.
T
Generally which proteins have a rapid rate of turnover, and which do not?
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
What is the amino acid pool meant for?
protein synthesis. When proteins depredate the amino acids go back to the protein pool.
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
stop
degradate through a process called transamination
Protein as fuel for exercise
how much does protein contribute to energy expenditure in resting conditions and exercise
15% resting
5% exercise
During very prolonged exercise, when carbohydrate availability becomes limited, _____ _____ ______ (mostly BCAAs) may increase somewhat to ___________
amino acid oxidation
10%
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:
protein synthesis
breakdown
net muscle protein gain will not occur
only after feeding a source of amino acids
muscle atrophy and weakness
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
48 hours
24 hours
muscle protein synthesis response
According to the diagram, what happens to the curve when there is a training stimulus
increased protein synthesis and net protein gains occur
T or F
A goal for athletes is to remain in a nitrogen-balanced state
T
Protein intake
Recommendation protein intake varies worldwide between:
0.8-1.2g/kg body weight
Unlike carbohydrate and fat, protein has generally :
not been associated with negative health effects
T or F
If are in excess in any Macronutrient, your body will store it as fat
T
For athletes, the recommendation of protein intake is approximately double that of non athletes, with a typical range of
1.2 to 2.0g/kg body weight
Strength athletes protein intake:
endurance athletes protein intake:
1.6-1.7g/kg body weight
1.2-1.8g/kg body weight
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
T
what is the main determinant of muscle strength and power
muscle size, cross-sectional area
What are the 5 factors affecting muscle tissue protein accretion following resistance training?
Amount of protein ingested
Time
Type
Leicine content
Coingestion of carbohydrate
Amount of protein ingested
Athletes:
Nonathletes:
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
Time of Protein Ingested
The scientific consensus now:
Is that it is optimal to ingest protein immediately after a bout of resistance exercise
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.
fast, slow
Whey and Soy
aminoacidemia and
muscle protein synthesis
Whole body protein synthesis is stimulated more with :
Whole body protein breakdown is suppressed with:
whey
caesin
Muscle protein synthesis was found to be greater with: both at rest and following resistance exercise
whey protein
Protein quality:
The two common methods for determining protein quality are
1.
2.
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.
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
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
Coingestion of carbs
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
Summary: Optimizing Muscle Protein Gain
- 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
- Proteins that are ________ digested and absorbed (ex. _____ ______) are most effective at generating increase in ______ _______
- Ingesting larger does of protein (____g/kg body wight) before bedtime appears to augment both acute and _________ MPS and skeletal muscle adaptations
20-25g
0.4g/kg body weight
3g
rapidly
Whey Protein
protein synthesis
0.6g/kg body weight
overnight
Excessive protein intakes can cause ________, kidney damage and athletes consuming high protein diet should therefore increase their ________ intake ti prevent dehydration
dehydration
fluid
Who may be at risk of Insufficient Protein Intake
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
