13a. Proteins & Amino Acids Flashcards
1
Q
What does protein mean in Greek?
A
Of first importance
2
Q
What percentage of our body weight is protein?
A
17%
3
Q
How many proteins is the body estimated to synthesise?
A
10,000
4
Q
What has protein been prized for in recent years?
A
Weight loss
Increased satiety
Muscle mass gains
5
Q
What do high animal protein diets increase the risk of?
A
Various diseases
Shortened life expectancy
6
Q
What compounds do proteins contain?
A
Carbon
Oxygen
Hydrogen
Nitrogen
7
Q
What are the basic building blocks of proteins?
A
Amino acids
8
Q
What does each amino acid contain?
A
Amino group - NH2
Carboxylic acid group - COOH
R group - unique and defines function of the AA
9
Q
What are proteins formed from?
A
A few dozen to several hundred amino acids
polypeptides
10
Q
How is the function of the amino acid determined?
A
By its 3D structure
11
Q
Are all amino acids building blocks?
A
No, some are non-proteins that aren’t encoded for in the genetic code
12
Q
How many amino acids does the body use?
A
20
13
Q
What are non-essential amino acids?
A
Ones the body can synthesise itself
14
Q
What are essential amino acids?
A
Ones the body can’t synthesise itself so need in the diet
15
Q
What are conditionally essential amino acids?
A
Non-essential AA that become essential under certain conditions
16
Q
What foods contain all 9 essential AAs?
A
Animal sourced protein
17
Q
How can a vegetarian/vegan diet supply all essential AAs?
A
Through consuming a variety of legumes, grains, nuts and seeds in a day
18
Q
Examples of non-essential AAs
A
Alanine Aspartic acid Glutamic acid Serine Asparagine Carnitine Creatine
19
Q
Examples of essential amino acids
A
Isoleucine Leucine Lysine Valine Methionine Phenylalanine Tryptophan Threonine Histidine
20
Q
What is a mnemonic to remember the essential amino acids?
A
I Love Lucy Very Much Please Try To Help
21
Q
Examples of conditionally essential AAs
A
Arginine Cysteine Glutamine Glycine Proline Tyrosine Taurine Theanine
22
Q
Why is histidine maybe not an essential AA?
A
Not synthesised in adults
Not needed for protein synthesis
23
Q
When can proteins be denatured?
A
Heat
pH
Alcohol
Heavy metals
24
Q
What happens to proteins when they become denatured?
A
Lose their 3D structure and function
25
What is proteolysis?
The breakdown of proteins
26
What is the function of proteolysis?
Making proteins more accessible to be worked on by proteolytic enzymes
27
What is the main protein digestive enzyme?
Pepsin
28
Examples of protein functions
```
Structure e.g. collagen
Hormones e.g. insulin, glucagon
Immunity e.g. immunoglobulins
Transport e.g. haemoglobin
Storage e.g. ferritin
Movement e.g. actin, myosin
Enzymes
Energy
```
29
How are proteins needed for growth/maintenance?
Collagen - bones, tendons, blood vessel walls
Actin/myosin - muscles
Cell replacement - new skin, GIT cells
30
Which AA is needed to make thyroid hormone?
Tryosine
31
Which AA is needed to make dopamine, norepinephrine and epinephrine?
Tyrosine
32
Which AA is needed to make serotonin and melatonin?
Tryptophan
33
Which hormone has two polypeptide chains?
Insulin
34
Which hormones have one polypeptide chain?
Glucagon
PTH
Calcitonin
35
What are receptors for hormones made from?
Cell membrane proteins
36
Which is the most abundant antibody protein in the body?
IgG
37
Which antibody protein is found in bodily secretions?
IgA
38
Which is the first antibody protein to appear in response to antigen exposure?
IgM
39
Which antibody protein is associated with allergic reactions?
IgE
40
How do some proteins provide a mode of transport for other nutrients?
Combining with other substances in the blood or within cells
41
Which nutrients does albumin bind to?
```
Ca
Zn
B6
Steroids
Fatty acids
```
42
Which nutrient does transferrin bind to?
Fe
43
Which nutrient does ceruloplasmin bind to?
Cu
44
Which gas does haemoglobin transport in the blood?
O2
45
What can be the cause of low serum albumin?
Protein malnutrition
Hypochlorhydria
Liver dysfunction
46
How can some AAs make good buffers?
```
Side chains (R group) can easily pick up or let go of H+
Helps regulate acid-base balance
```
47
Which two AAs can act as buffers in the body?
Histidine
| Cysteine
48
How is fluid balance maintained by proteins?
```
The protein (albumin) attracts water
If protein levels are too low, water leaks out of the blood vessels and accumulates in interstitial spaces causing oedema
```
49
What is the osmotic pressure from proteins in fluid called?
Oncotic pressure
50
What are the protein-related causes of oedema?
Excessive protein losses due to kidney disease
Inadequate protein synthesis due to liver disease
Inadequate dietary intake of protein due to malnutrition
(e.g. ascites - distended abdomens in famine situations)
51
What are glycoproteins?
Proteins bound to a sugar molecule
52
Examples of glycoproteins
```
Mucins
ABO blood type antigens
Hormones
Major Histocompatibility Complex
Proteoglycans
```
53
Where can mucins be found?
Mucus
| Saliva
54
What is the function of mucins?
Provides protective, lubricating barrier
55
Which hormones are glycoproteins?
Luteinising hormone
Follicle stimulating hormone
Thyroid stimulating hormone
56
What are proteoglycans?
```
A subclass of glycoproteins
Bound to glycosaminoglycans (GAGs)
```
57
Where are proteoglycans found?
Extracellular matrix
| e.g cartilage
58
What is deamination?
Removal of a nitrogen containing amine group
59
Why does deamination need to happen?
For individual AAs to be used as energy or stored as fat
60
Where does deamination usually occur?
Liver
61
What is formed when the nitrogen group is removed from the AA during deamination?
Ammonia
62
How is ammonia made less toxic and water-soluble?
Goes through a series of transformation reactions in the liver called the urea cycle
63
What is the less toxic, water-soluble version of ammonia called?
Urea
64
How is urea filtered out of the body?
By the kidneys in urine
65
What can the fragments of AAs left behind from deamination be used for?
Produce glucose
| Produce ketones
66
Where does the urea cycle take place?
Liver
67
Which AAs are made in the body as a result of the urea cycle?
Arginine
Citrulline
Ornithine
68
What can impairments to the urea cycle lead to?
Hyperammonaemia
69
What are the symptoms of hyperammonaemia?
```
Chronic fatigue
Headaches
Irritability
Nausea
Diarrhoea
Poor concentration
Confusion
Intolerance of high protein foods
```
70
What is transamination?
The synthesis of non-essential AAs from another
71
How does transamination happen?
Amino group of an AA is transferred onto an enzyme
| The enzyme then transfers the amino group to a ketoacid - forming a new AA
72
Which nutrient is transamination reliant on?
B6
73
Which foods is B6 abundant in?
```
Wholegrains
Green veg
Sunflower seeds
Walnuts
Bananas
Lentils
Avocados
Meat
Fish
```
74
What is protein turnover?
Where proteins in the body are continually being broken down and made into new proteins
75
What happens to proteins when they are broken down?
The free amino acids join the general circulation with diet-derived AAs
76
What is the general circulation of freed AAs and diet-derived AAs called?
Amino acid pool
77
What happens to AAs in the amino acid pool?
Utilised or excreted
78
Why do essential AAs generally have a longer half life?
They are more critical to the body
79
Why is it important to have a regular intake of protein?
Protein isn't stored in the body
| It's used or excreted
80
What happens if the body needs essential AAs and they're not available?
The body will break down its own tissues to obtain them
81
What effect does stress have on protein in the body?
Can lead to protein losses in skeletal muscle - cortisol
Can lead to protein losses in the extracellular matrix - collagen
(chronic stress can lead to osteoporosis)
82
When are AAS used for energy?
When glucose or fatty acids are limited
83
In what situations would AAs be needed for energy?
Starvation
Prolonged fasting
Metabolic disorders
84
What happens in the body when protein is needed for energy?
Body dismantles tissue proteins for energy
85
What happens to lean tissue over a period of energy deprivation?
Tissue wasting
86
In which foods can protein be found?
```
Legumes
Nuts
Seeds
Greens
Wholegrains
Eggs
Fish
Poultry
Meats
Fruit
Honey
```
87
In which foods won't you find protein?
Refined sugar
| Oils
88
Where does the body reabsorb protein from?
Shed mucosal cells (50g)
| Digestive enzymes/glycoproteins (17g)
89
Why is meat maybe a not so good source of protein?
Requires more energy to digest than plant sources
Can accumulate in the intestinal wall, impairing absorption
Added extras to meat meals e.g. bacon, cheese, brings with it high calories, trans fats, reducing the benefits of the meat
90
What factors determine protein quality?
Digestibility
| AA composition
91
What can effect the digestibility of protein?
Gut function (HCl and digestive enzymes)
Presence of fibre
Anti-nutrient factors e.g. phytates, lectins
92
How can the digestibility of plant protein sources be supported?
Soaking
Sprouting
Fermenting
93
What do plant sources of protein contain that make them a better choice for healthy eating?
Fibre
Prebiotics
Phytonutrients
94
How can you optimise protein digestion?
```
Chew thoroughly
Avoid drinking with meals
Zn and B6 rich foods
ACV in a little water before meals
Bitter herbs
```
95
What happens to undigested protein in the intestinal tract?
Reaches the colon fermented
Creates toxic metabolites
Inflammatory response increases
Proliferation of opportunistic pathogens
96
Examples of fermented products from protein
Ammonia
Amines
Sulphides
N-nitroso compounds
97
What effects can fermented proteins have on the body?
Systemic toxicity
Nephrotoxicity
Carcinogenesis
98
To make a protein what must a cell have available?
All the required AAs
99
If one essential AA is missing to make a protein what happens?
The cell has to cease making the protein
| The cell must dismantle another protein to obtain it
100
What is a limiting AA?
When an essential AA is supplied in less than the amount needed to support protein synthesis
101
Examples of limiting AA?
Lysine
Threonine
Methionine
Tryptophan
102
What is a complete protein?
Food that contains all of the nine essential amino acids
103
Examples of vegan foods that are complete proteins
```
Quinoa
Buckwheat
Pumpkin seeds
Chia seeds
Hemp seeds
Tempeh
```
104
What is an incomplete protein?
Food low in one or more of the essential amino acids
105
Examples of food combining to obtain all essential amino acids
Vegetables + grains
Grains + legumes
Legumes + nuts/seeds
106
What are some negative effects of high animal protein diets?
Excess methionine
| Ingestion of pesticides
107
Why is excess methionine bad for the body?
Has an immune stimulating effect on T-cells so excess can lead to AI and chronic inflammation
Increases homocysteine - associated with atherosclerosis
108
How can pesticides get in to meat?
Oral/topical dosing of animal to control lice/fleas
| Pesticides in animal feed
109
Which conditions can excess intake of animal protein lead to?
```
Atherosclerosis
Osteoporosis
Kidney disease
Increased cancer risk
Liver disorders
Increased muscle soreness post-exercise
```
110
Why is the intake of plant protein better for us?
Alkaline-rich fruit and veg buffer the protein derived acid load
111
Why does moderate/high intake of animal protein increase cancer risk?
Initiation/promotion
112
Which red meats are seen as carcinogens?
Salted
Cured
Fermented
Smoked
113
What are the carcinogenic compounds produced during the cooking of meat at high temperatures?
```
Polycyclic aromatic hydrocarbons (PAHs)
Heterocyclic amines (HCAs)
```
114
How does excess animal protein increase the risk of osteoporosis?
Acidic burden of excess animal protein can draw calcium out of bones
115
How can a protein deficiency negatively effect bone health?
Reduces collagen production/structure within bone
116
How does excess animal protein intake increase the risk of kidney disease?
Extra acidity from high animal protein needs buffering by the kidneys
Kidneys also filter the increased urea that's generated
117
How does excess animal protein increase the risk of CV disease?
Oxidation and inflammation in the endothelium
118
Why are plant-based proteins more beneficial to health?
Presence of health-supporting fibre, phytonutrients, prebiotics
119
Which conditions can plant-based proteins be protective against?
Cancer
AI
Diabetes
CV disease
120
How can plant-based protein assist with healthy ageing?
Lower levels of leucine which can increase the expression of the TOR enzyme
121
What does the TOR enzyme do?
Regulates cell growth by decreasing autophagy
| therefore increasing ageing
122
Why is breast milk perfect nutrition for infants?
Quite low in protein
123
Why is low protein good for infants?
Kidneys aren't developed enough to cope with protein
124
Why is it difficult to determine protein requirements?
There are no physiological deficiency symptoms other than severe deficiency
(e.g. growth failure, muscle wasting)
125
At what values is it estimated that the risk of protein deficiency could start?
0. 4-0.5g/kg of body weight
| e. g. 31.5g or below for a 70kg person
126
Why do athletes need a higher protein requirement?
Due to increased catabolism of amino acids occurring during exercise
127
What is the general recommendation for protein intake?
0.75g/kg of body weight
128
To meet the functional needs of athletes what is the recommended intake of protein for minimal physical activity?
1.0g of protein per kg of body weight
129
To meet the functional needs of athletes what is the recommended intake of protein for moderate physical activity?
1.3g of protein per kg of body weight
130
To meet the functional needs of athletes what is the recommended intake of protein for intense physical activity?
1.6g of protein per kg of body weight
131
Why are protein supplements unnecessary to meet additional protein requirements in athletes?
As the increased need for protein will likely be met through a proportion of the increased calorie requirements
132
How can you calculate protein intake for an average client?
Look up the healthy weight for a person of the client's height
Use the midpoint of the healthy weight range to base calculations
Multiply kg by 0.75 to get RNI
133
How much additional protein is recommended during pregnancy?
Additional 6g/day
134
How much additional protein is recommended during lactation (0-6 months)?
11g/day
135
How much additional protein is recommended during lactation (6+ months)?
8g/day
136
What is the recommended protein intake for vegans/vegetarians?
1g per kg of body weight
| to accommodate lower protein bioavailability
137
Who, in the developed world, is protein deficiency more likely to affect?
```
Children
Teenagers
Older people
Anorexia nervosa sufferers
Recovering patients
Homeless
Drug/alcohol addictions
Chronic digestive conditions
Chronic use of PPIs
Chronic/active infections
```
138
How can protein deficiency come about in children?
When diets are rich in highly refined/processed foods, high sugar and soft drinks
Low in quality wholefoods
139
How can protein deficiency come about in teenagers?
Dieting
| Consuming on highly refined/processed foods/junk food, soft drinks
140
How can protein deficiency come about in older people?
Reduced intake, digestion and absorption due to:
Poor chewing
Poor digestive health
Living situation
141
What functions can AAs not on the essential list have?
```
Synthesis of hormones/neurotransmitters
Act as neurotransmitters
Act as methyl donors
Build bile acids for digestion
Act as precursors for nitric oxide production
Help detoxify chemicals
```
142
How can the amino acid status of a person be assessed?
Plasma
| Urine samples
143
When can an AA assessment be useful?
CFS (due to mitochondrial inefficiency)
| Long term PPI use (reduced AA absorption)
144
What could a CV disease risk screen tell us?
Higher levels of branched chain amino acids and homocysteine linked to heart disease
(lower dietary intake)
145
Which are the branched chain amino acids?
Leucine
Isoleucine
Valine
