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Nutrition 1 (Semester II) > 13a. Proteins & Amino Acids > Flashcards

13a. Proteins & Amino Acids Flashcards

1
Q

What does protein mean in Greek?

A

Of first importance

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2
Q

What percentage of our body weight is protein?

A

17%

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3
Q

How many proteins is the body estimated to synthesise?

A

10,000

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4
Q

What has protein been prized for in recent years?

A

Weight loss
Increased satiety
Muscle mass gains

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5
Q

What do high animal protein diets increase the risk of?

A

Various diseases

Shortened life expectancy

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6
Q

What compounds do proteins contain?

A

Carbon
Oxygen
Hydrogen
Nitrogen

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7
Q

What are the basic building blocks of proteins?

A

Amino acids

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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

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9
Q

What are proteins formed from?

A

A few dozen to several hundred amino acids

polypeptides

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10
Q

How is the function of the amino acid determined?

A

By its 3D structure

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11
Q

Are all amino acids building blocks?

A

No, some are non-proteins that aren’t encoded for in the genetic code

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12
Q

How many amino acids does the body use?

A

20

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13
Q

What are non-essential amino acids?

A

Ones the body can synthesise itself

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14
Q

What are essential amino acids?

A

Ones the body can’t synthesise itself so need in the diet

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15
Q

What are conditionally essential amino acids?

A

Non-essential AA that become essential under certain conditions

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16
Q

What foods contain all 9 essential AAs?

A

Animal sourced protein

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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

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18
Q

Examples of non-essential AAs

A 
Alanine
Aspartic acid
Glutamic acid
Serine
Asparagine
Carnitine
Creatine
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19
Q

Examples of essential amino acids

A 
Isoleucine
Leucine
Lysine
Valine
Methionine
Phenylalanine
Tryptophan
Threonine
Histidine
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20
Q

What is a mnemonic to remember the essential amino acids?

A

I Love Lucy Very Much Please Try To Help

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21
Q

Examples of conditionally essential AAs

A 
Arginine
Cysteine
Glutamine
Glycine
Proline
Tyrosine
Taurine
Theanine
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22
Q

Why is histidine maybe not an essential AA?

A

Not synthesised in adults

Not needed for protein synthesis

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23
Q

When can proteins be denatured?

A

Heat
pH
Alcohol
Heavy metals

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24
Q

What happens to proteins when they become denatured?

A

Lose their 3D structure and function

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25
Q

What is proteolysis?

A

The breakdown of proteins

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26
Q

What is the function of proteolysis?

A

Making proteins more accessible to be worked on by proteolytic enzymes

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27
Q

What is the main protein digestive enzyme?

A

Pepsin

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28
Q

Examples of protein functions

A 
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
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29
Q

How are proteins needed for growth/maintenance?

A

Collagen - bones, tendons, blood vessel walls
Actin/myosin - muscles
Cell replacement - new skin, GIT cells

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30
Q

Which AA is needed to make thyroid hormone?

A

Tryosine

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31
Q

Which AA is needed to make dopamine, norepinephrine and epinephrine?

A

Tyrosine

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32
Q

Which AA is needed to make serotonin and melatonin?

A

Tryptophan

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33
Q

Which hormone has two polypeptide chains?

A

Insulin

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34
Q

Which hormones have one polypeptide chain?

A

Glucagon
PTH
Calcitonin

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35
Q

What are receptors for hormones made from?

A

Cell membrane proteins

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36
Q

Which is the most abundant antibody protein in the body?

A

IgG

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37
Q

Which antibody protein is found in bodily secretions?

A

IgA

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38
Q

Which is the first antibody protein to appear in response to antigen exposure?

A

IgM

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39
Q

Which antibody protein is associated with allergic reactions?

A

IgE

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40
Q

How do some proteins provide a mode of transport for other nutrients?

A

Combining with other substances in the blood or within cells

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41
Q

Which nutrients does albumin bind to?

A 
Ca
Zn
B6
Steroids
Fatty acids
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42
Q

Which nutrient does transferrin bind to?

A

Fe

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43
Q

Which nutrient does ceruloplasmin bind to?

A

Cu

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44
Q

Which gas does haemoglobin transport in the blood?

A

O2

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45
Q

What can be the cause of low serum albumin?

A

Protein malnutrition
Hypochlorhydria
Liver dysfunction

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46
Q

How can some AAs make good buffers?

A 
Side chains (R group) can easily pick up or let go of H+
Helps regulate acid-base balance
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47
Q

Which two AAs can act as buffers in the body?

A

Histidine

Cysteine

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48
Q

How is fluid balance maintained by proteins?

A 
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
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49
Q

What is the osmotic pressure from proteins in fluid called?

A

Oncotic pressure

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50
Q

What are the protein-related causes of oedema?

A

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)

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51
Q

What are glycoproteins?

A

Proteins bound to a sugar molecule

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52
Q

Examples of glycoproteins

A 
Mucins
ABO blood type antigens
Hormones
Major Histocompatibility Complex
Proteoglycans
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53
Q

Where can mucins be found?

A

Mucus

Saliva

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54
Q

What is the function of mucins?

A

Provides protective, lubricating barrier

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55
Q

Which hormones are glycoproteins?

A

Luteinising hormone
Follicle stimulating hormone
Thyroid stimulating hormone

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56
Q

What are proteoglycans?

A 
A subclass of glycoproteins
Bound to glycosaminoglycans (GAGs)
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57
Q

Where are proteoglycans found?

A

Extracellular matrix

e.g cartilage

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58
Q

What is deamination?

A

Removal of a nitrogen containing amine group

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59
Q

Why does deamination need to happen?

A

For individual AAs to be used as energy or stored as fat

60
Q

Where does deamination usually occur?

A

Liver

61
Q

What is formed when the nitrogen group is removed from the AA during deamination?

A

Ammonia

62
Q

How is ammonia made less toxic and water-soluble?

A

Goes through a series of transformation reactions in the liver called the urea cycle

63
Q

What is the less toxic, water-soluble version of ammonia called?

A

Urea

64
Q

How is urea filtered out of the body?

A

By the kidneys in urine

65
Q

What can the fragments of AAs left behind from deamination be used for?

A

Produce glucose

Produce ketones

66
Q

Where does the urea cycle take place?

A

Liver

67
Q

Which AAs are made in the body as a result of the urea cycle?

A

Arginine
Citrulline
Ornithine

68
Q

What can impairments to the urea cycle lead to?

A

Hyperammonaemia

69
Q

What are the symptoms of hyperammonaemia?

A 
Chronic fatigue
Headaches
Irritability
Nausea
Diarrhoea
Poor concentration
Confusion
Intolerance of high protein foods
70
Q

What is transamination?

A

The synthesis of non-essential AAs from another

71
Q

How does transamination happen?

A

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
Q

Which nutrient is transamination reliant on?

A

B6

73
Q

Which foods is B6 abundant in?

A 
Wholegrains
Green veg
Sunflower seeds
Walnuts
Bananas
Lentils
Avocados
Meat
Fish
74
Q

What is protein turnover?

A

Where proteins in the body are continually being broken down and made into new proteins

75
Q

What happens to proteins when they are broken down?

A

The free amino acids join the general circulation with diet-derived AAs

76
Q

What is the general circulation of freed AAs and diet-derived AAs called?

A

Amino acid pool

77
Q

What happens to AAs in the amino acid pool?

A

Utilised or excreted

78
Q

Why do essential AAs generally have a longer half life?

A

They are more critical to the body

79
Q

Why is it important to have a regular intake of protein?

A

Protein isn’t stored in the body

It’s used or excreted

80
Q

What happens if the body needs essential AAs and they’re not available?

A

The body will break down its own tissues to obtain them

81
Q

What effect does stress have on protein in the body?

A

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
Q

When are AAS used for energy?

A

When glucose or fatty acids are limited

83
Q

In what situations would AAs be needed for energy?

A

Starvation
Prolonged fasting
Metabolic disorders

84
Q

What happens in the body when protein is needed for energy?

A

Body dismantles tissue proteins for energy

85
Q

What happens to lean tissue over a period of energy deprivation?

A

Tissue wasting

86
Q

In which foods can protein be found?

A 
Legumes
Nuts
Seeds
Greens
Wholegrains
Eggs
Fish 
Poultry
Meats
Fruit
Honey
87
Q

In which foods won’t you find protein?

A

Refined sugar

Oils

88
Q

Where does the body reabsorb protein from?

A

Shed mucosal cells (50g)

Digestive enzymes/glycoproteins (17g)

89
Q

Why is meat maybe a not so good source of protein?

A

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
Q

What factors determine protein quality?

A

Digestibility

AA composition

91
Q

What can effect the digestibility of protein?

A

Gut function (HCl and digestive enzymes)
Presence of fibre
Anti-nutrient factors e.g. phytates, lectins

92
Q

How can the digestibility of plant protein sources be supported?

A

Soaking
Sprouting
Fermenting

93
Q

What do plant sources of protein contain that make them a better choice for healthy eating?

A

Fibre
Prebiotics
Phytonutrients

94
Q

How can you optimise protein digestion?

A 
Chew thoroughly
Avoid drinking with meals
Zn and B6 rich foods
ACV in a little water before meals
Bitter herbs
95
Q

What happens to undigested protein in the intestinal tract?

A

Reaches the colon fermented
Creates toxic metabolites
Inflammatory response increases
Proliferation of opportunistic pathogens

96
Q

Examples of fermented products from protein

A

Ammonia
Amines
Sulphides
N-nitroso compounds

97
Q

What effects can fermented proteins have on the body?

A

Systemic toxicity
Nephrotoxicity
Carcinogenesis

98
Q

To make a protein what must a cell have available?

A

All the required AAs

99
Q

If one essential AA is missing to make a protein what happens?

A

The cell has to cease making the protein

The cell must dismantle another protein to obtain it

100
Q

What is a limiting AA?

A

When an essential AA is supplied in less than the amount needed to support protein synthesis

101
Q

Examples of limiting AA?

A

Lysine
Threonine
Methionine
Tryptophan

102
Q

What is a complete protein?

A

Food that contains all of the nine essential amino acids

103
Q

Examples of vegan foods that are complete proteins

A 
Quinoa
Buckwheat
Pumpkin seeds
Chia seeds
Hemp seeds
Tempeh
104
Q

What is an incomplete protein?

A

Food low in one or more of the essential amino acids

105
Q

Examples of food combining to obtain all essential amino acids

A

Vegetables + grains
Grains + legumes
Legumes + nuts/seeds

106
Q

What are some negative effects of high animal protein diets?

A

Excess methionine

Ingestion of pesticides

107
Q

Why is excess methionine bad for the body?

A

Has an immune stimulating effect on T-cells so excess can lead to AI and chronic inflammation
Increases homocysteine - associated with atherosclerosis

108
Q

How can pesticides get in to meat?

A

Oral/topical dosing of animal to control lice/fleas

Pesticides in animal feed

109
Q

Which conditions can excess intake of animal protein lead to?

A 
Atherosclerosis
Osteoporosis
Kidney disease
Increased cancer risk
Liver disorders
Increased muscle soreness post-exercise
110
Q

Why is the intake of plant protein better for us?

A

Alkaline-rich fruit and veg buffer the protein derived acid load

111
Q

Why does moderate/high intake of animal protein increase cancer risk?

A

Initiation/promotion

112
Q

Which red meats are seen as carcinogens?

A

Salted
Cured
Fermented
Smoked

113
Q

What are the carcinogenic compounds produced during the cooking of meat at high temperatures?

A 
Polycyclic aromatic hydrocarbons (PAHs)
Heterocyclic amines (HCAs)
114
Q

How does excess animal protein increase the risk of osteoporosis?

A

Acidic burden of excess animal protein can draw calcium out of bones

115
Q

How can a protein deficiency negatively effect bone health?

A

Reduces collagen production/structure within bone

116
Q

How does excess animal protein intake increase the risk of kidney disease?

A

Extra acidity from high animal protein needs buffering by the kidneys
Kidneys also filter the increased urea that’s generated

117
Q

How does excess animal protein increase the risk of CV disease?

A

Oxidation and inflammation in the endothelium

118
Q

Why are plant-based proteins more beneficial to health?

A

Presence of health-supporting fibre, phytonutrients, prebiotics

119
Q

Which conditions can plant-based proteins be protective against?

A

Cancer
AI
Diabetes
CV disease

120
Q

How can plant-based protein assist with healthy ageing?

A

Lower levels of leucine which can increase the expression of the TOR enzyme

121
Q

What does the TOR enzyme do?

A

Regulates cell growth by decreasing autophagy

therefore increasing ageing

122
Q

Why is breast milk perfect nutrition for infants?

A

Quite low in protein

123
Q

Why is low protein good for infants?

A

Kidneys aren’t developed enough to cope with protein

124
Q

Why is it difficult to determine protein requirements?

A

There are no physiological deficiency symptoms other than severe deficiency
(e.g. growth failure, muscle wasting)

125
Q

At what values is it estimated that the risk of protein deficiency could start?

A
  1. 4-0.5g/kg of body weight

e. g. 31.5g or below for a 70kg person

126
Q

Why do athletes need a higher protein requirement?

A

Due to increased catabolism of amino acids occurring during exercise

127
Q

What is the general recommendation for protein intake?

A

0.75g/kg of body weight

128
Q

To meet the functional needs of athletes what is the recommended intake of protein for minimal physical activity?

A

1.0g of protein per kg of body weight

129
Q

To meet the functional needs of athletes what is the recommended intake of protein for moderate physical activity?

A

1.3g of protein per kg of body weight

130
Q

To meet the functional needs of athletes what is the recommended intake of protein for intense physical activity?

A

1.6g of protein per kg of body weight

131
Q

Why are protein supplements unnecessary to meet additional protein requirements in athletes?

A

As the increased need for protein will likely be met through a proportion of the increased calorie requirements

132
Q

How can you calculate protein intake for an average client?

A

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
Q

How much additional protein is recommended during pregnancy?

A

Additional 6g/day

134
Q

How much additional protein is recommended during lactation (0-6 months)?

A

11g/day

135
Q

How much additional protein is recommended during lactation (6+ months)?

A

8g/day

136
Q

What is the recommended protein intake for vegans/vegetarians?

A

1g per kg of body weight

to accommodate lower protein bioavailability

137
Q

Who, in the developed world, is protein deficiency more likely to affect?

A 
Children
Teenagers
Older people
Anorexia nervosa sufferers
Recovering patients
Homeless
Drug/alcohol addictions
Chronic digestive conditions
Chronic use of PPIs
Chronic/active infections
138
Q

How can protein deficiency come about in children?

A

When diets are rich in highly refined/processed foods, high sugar and soft drinks
Low in quality wholefoods

139
Q

How can protein deficiency come about in teenagers?

A

Dieting

Consuming on highly refined/processed foods/junk food, soft drinks

140
Q

How can protein deficiency come about in older people?

A

Reduced intake, digestion and absorption due to:
Poor chewing
Poor digestive health
Living situation

141
Q

What functions can AAs not on the essential list have?

A 
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
Q

How can the amino acid status of a person be assessed?

A

Plasma

Urine samples

143
Q

When can an AA assessment be useful?

A

CFS (due to mitochondrial inefficiency)

Long term PPI use (reduced AA absorption)

144
Q

What could a CV disease risk screen tell us?

A

Higher levels of branched chain amino acids and homocysteine linked to heart disease
(lower dietary intake)

145
Q

Which are the branched chain amino acids?

A

Leucine
Isoleucine
Valine

Nutrition 1 (Semester II) (16 decks)

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