Protein Flashcards
1
Q
What are the roles of protein?
A
- Structure
- Transport
- Immune Function
- Contraction
- Metabolic Regulation
- Acid-base Balance
2
Q
What is low muscle mass associated with?
A
Increased morbidity, poorer quality of life and higher mortality
3
Q
What is low muscle strength associated with?
A
Shown to be a significant and independent predictor of mortality risk
4
Q
What is the composition of amino acids?
A
Amino acids contain carbon, hydrogen and oxygen, but also contain nitrogen
5
Q
What is the structure of amino acids?
A
- Carboxyl group
- Amine group
- Variable group
- Each amino acid has a difference side chain
6
Q
What is the side chain (R group)?
A
The R group is the one that causes the different amino acids
7
Q
How many amino acids are there?
A
20
8
Q
What are the categories of amino acids?
A
Essential and non-essential
9
Q
What are essential amino acids?
A
They cannot be synthesised by the body and must be consumed in the diet
10
Q
What are non-essential amino acids?
A
Can be synthesised from other amino acids via transamination
11
Q
How many branched chain amino acids are there?
A
- 3 - Isoleucine, Leucine, Valine
- They are the amino acids that can cross the blood brain barrier
12
Q
What is leucine?
A
- A branched chain amino acid
- Important in triggering muscle protein synthesis
13
Q
What are the classifications of protein?
A
- Dipeptide - two amino acids joined by a peptide bond
- Polypeptide - longer chains of more than 20 amino acids
- Proteins - consist of one or more polypeptides
14
Q
What are the structures of protein?
A
- Primary
- Secondary
- Tertiary
15
Q
What is the primary structure of protein?
A
- The amino acid sequence
- Like beads on a string
16
Q
What is the secondary structure of protein?
A
- Determined by the interactions between groups
- Helix (like DNA)
- Beta pleated sheets or fold (like corrugated iron)
17
Q
What is the tertiary structure of protein?
A
- Determined by interactions between side chains (3D)
- Like pipe cleaners
18
Q
What are the 3 areas that protein digestion occurs?
A
- Stomach
- Pancreas
- Small intestine
19
Q
What happens in protein digestion in the stomach?
A
- Hydrochloric acid:
- Breaks down proteins to smaller polypeptides
- Activates stomach enzymes
20
Q
What happens in protein digestion in the pancreas?
A
Enzymes include trypsin and chymotrypsin degrade polypeptides to oligopeptides and amino acids
21
Q
What happens in protein digestion in the small intestine?
A
- Aminopeptidase degrades oligopeptides to peptides and amino acids
- AA and small peptides are transported across the intestinal membrane
- Peptides are hydrolysed in the cytosol and so enter the circulation
22
Q
How much protein do we store?
A
We don’t store much protein or amino acids - there are some in the blood and ECF but very minimal
23
Q
What happens to proteins once they are digested and absorbed?
A
- Goes into the protein pool and can be used by the liver and muscle
- Liver plays a really important role in regulating protein breakdown and excretion
24
Q
What does muscle mass maintenance mean?
A
Muscle protein synthesis = muscle protein breakdown
25
What does muscle mass gain mean?
Muscle protein synthesis > muscle protein breakdown
26
What is the most important factor for muscle protein synthesis?
Exercise - stimulates the muscle to be able to become more anabolic and build muscle
27
What is muscle protein synthesis?
- Varies between different dietary protein sources
- Depends on post-prandial rise in plasma essential amino acid concentrations
- Plasma amino acid concentrations also provide the necessary precursors for protein synthesis rates to increase
- Ingesting 20-25g whey protein strongly increases muscle protein synthesis rates
28
What is protein quality?
How many essential amino acids are in it and in what amount (what comes in it)
29
What are complete proteins?
All essential amino acids are present
30
What are incomplete proteins?
Plant proteins are deficient in one essential amino acid
31
Whats the protein quality for vegetarians?
- Digestibility
- Cell walls of plant proteins (inhibit digestion)
- Anti-nutritional factors (inhibit digestion)
32
What are complimenting proteins?
- Combining proteins to try match the missing sources of amino acids
- Doesn't have to be in the same meal but throughout the day
33
Is egg a complete or incomplete protein source?
Complete
34
Is meat a complete or incomplete protein source?
Complete
35
Is fish a complete or incomplete protein source?
Complete
36
Is dairy a complete or incomplete protein source?
Complete
37
Is soy a complete or incomplete protein source?
Incomplete - missing methionine
38
Is corn a complete or incomplete protein source?
Incomplete - missing lysine and tryptophan
39
Is legumes a complete or incomplete protein source?
Incomplete - missing methionine, tryptophan and cystein
40
Is rice a complete or incomplete protein source?
Incomplete - missing lysine
41
Is wheat a complete or incomplete protein source?
Incomplete - missing lysine
42
What does PDCAAS mean?
- Protein digestibility-corrected amino acid score
- The higher the number, the higher the quality
43
How does heat affect protein quality?
Heat can affect the food matrix (eg. food structure) to affect protein quality scores. The way you process something has an impact as well
44
What effect does whey protein have on muscle protein synthesis?
- Has really fast muscle protein synthesis
- Empties much quicker out of the stomach as well
45
What is the rate of absorption for plant and animal based foods?
- Plant based whole foods have lower absorbability when compared with animal-based whole foods
- 85-95% of the protein in egg whites, whole eggs, and chicken is absorbed
- 50-75% of the protein in chickpeas, mung beans and yellow peas
46
Why do plant-based protein sources take longer to absorb?
Because of the anti-nutritional factors eg. fibre and polyphenolic tannins attenuate absorption
47
Whats the difference between wheat and whey protein?
- Wheat is plant protein
- Whey is animal protein
48
How much whey protein do you need to ingest to strongly increase muscle protein synthesis rates ?
20-25g whey protein, which provides 2.2-2.7g leucine.
49
What is the potential solution for low protein content?
Protein extraction
50
What is the potential solution for low protein and low in a specific essential amino acid?
Protein fortification
51
What is the potential solution for low in specific essential amino acids?
Protein blends
52
What is the potential solution for overall low essential amino acid content?
Increase protein intake
53
Do animal or plant protein sources have higher protein quality?
Animal protein has higher protein quality and is usually considered to be superior to plant protein for building muscle mass
54
What do health professionals encourage around plant and animal protein?
That we replace animal protein, especially red meat, with plant protein to help decrease the risk of cardiovascular diseases. Also reduces harm to the environment, limiting the greenhouse gas emissions associated with animal farming
55
How much protein do you need to maximise protein synthesis?
No right or wrong answer but tends to be around 20-30g repeated 4-5x across the day to optimise the response over the day. Current evidence suggests an intake of 0.3-0.4g/kg
56
When is the peak in muscle protein synthesis after you eat?
Peak after you eat lasts between 2-3 hours, so eating 20-30g of protein every 2-3hours will optimise protein synthesis throughout the dat.
57
Should you eat right before bed?
Its beneficial to eat something before bed to increase the muscle protein synthesis overnight - casein might be best as its slower
58
Should you have protein within 30minutes of exercise?
Having something to eat containing protein within that 30mins means that later on you will have elevated protein synthesis rates. So you can really benefit from spreading the intake throughout the day rather then having it in the 30minute window
59
Is whole egg or egg white better for protein synthesis?
Whole egg
60
Why is the whole egg better for protein synthesis?
Because the whole egg matrix is rich in high quality dietary protein, lipids, vitamins and minerals compared to the egg white matrix. So the non-protein components of the whole egg may have a role in various aspects of the regulation of muscle protein synthesis
61
What part of recovery nutrition does protein come into?
- Repair: muscle repair and regeneration
- 20-30g
62
What sort of protein should you have in recovery and when?
- The timing and composition of the recovery food depend on the level of athlete, length and intensity of the exercise session, and when the next intense workout will occur
- Eating a source of high-quality protein soon after exercise will promote muscle protein synthesis
- It may be helpful to choose a protein source that is rapidly digested ie. whey protein
