8: Proteins Flashcards
1
Q
what are proteins
A
Organic molecules composed of folded long chains of amino acids
2
Q
how is protein an energy yielding nutrient?
A
promote tissue growth and repair
3
Q
what are the effects of protein deficiencies?
A
can hinder a person’s ability to grow and thrive
4
Q
what is the structure of amino acids?
A
Amino acids contain a nitrogen containing amine group, a carboxylic acid group, and a side chain (Rx)
5
Q
how many amino acids are there and where can they be found?
A
21 amino acids found in foods/bodies, structurally identical expect their side chains
6
Q
T/F: All amino acids are essential
A
False,
- Only nine amino acids are essential
- Some amino acids are essential from the diet, while others can be synthesized by the body from other amino acids
7
Q
what does it mean when an amino acid is essential?
A
These are absolutely required from the diet because the body cannot make them itself
8
Q
what is the process of Transamination?
A
the non-essential amino acids can be made by modifying other amino acids
9
Q
what are conditionally essential amino acids and how many are there?
A
6 are considered conditionally essential, because they become essential when the body is not able to synthesize adequate amounts
10
Q
what causes conditionally essential amino acids to occur?
A
certain disease states
11
Q
how is a food considered a complete protein?
A
complete proteins are foods that have all 9 amino acids
12
Q
T/F: All animal and plant products are complete proteins
A
False,
animal products are complete proteins, while plant products are typically incomplete proteins
13
Q
how is a food considered an incomplete protein?
A
incomplete proteins are foods that are missing one or more essential amino acids called Limiting Amino Acids
14
Q
what is the concept of complementing proteins or mutual complementation?
A
by eating lots of plant sources of protein, all essential amino acids can be consumed
15
Q
give some food examples of complementing incomplete proteins
A
Rice and Beans,
Pita with Hummus,
Peanut Butter on Bread
16
Q
what are the few plant products that are complete proteins
A
soy, tofu, quinoa and buckwheat
17
Q
T/F: To become part of a fully functional protein, amino acids must bind together in a specific order
A
True,
Our DNA holds the instructions for the sequence of amino acids needed in order to build specific proteins
18
Q
What is the amino acid pool
A
to build the sequence of amino acids, the body draws on the amino acid pool, a reservoir of amino acids that are available for making protein
19
Q
what happens if the diet lacks a non-essential amino acid
A
the liver can make it from another one through transamination
20
Q
what happens if the diet lacks an essential amino acid
A
it is not available for the amino acid chain and protein synthesis stops
21
Q
what does the phrase “DNA has the blueprints for life”
A
DNA has the blueprints for making the various proteins that contribute to the structure and funcon of organisms, including humans
22
Q
how to make a protein
A
1) RNA makes copy of DNA code for particular gene
2) RNA message has code that dictates sequence of amino acids needed to build specific protein. these amino acids are drawn from the amino acid pool
23
Q
T/F: A polypeptide chain is not a functional protein
A
True,
A polypeptide chain is not a functional protein unless it folds in a specific way to form its secondary, tertiary and quaternary structure
24
Q
how is the first level of protein structure started
A
adjacent amino acids bonding to each other
though a condensation reaction leading to the formation of a peptide bond
25
peptide bonds lead to the formation of what
peptide bonds help build the polypeptide chain
26
what factors determine how the protein folds to form its secondary, tertiary and quaternary structures and eventually the protein's function?
The amino acid order in the polypeptide chain (which amino acids are located where) and the chain length
27
T/F: The primary structure is therefore critical to that protein’s role in the body
True
28
what is the secondary structure of a protein?
hydrogen bonds between non-adjacent amino acids lead to the formation of Alpha helices and beta-pleated sheets
29
what is the tertiary structure of a protein?
interactions between amino acid side chains leads to further folding of the polypeptide chain and may result in a functional protein
30
what are several bonds that can occur between tertiary structure side chains
salt bridges and disulfide bonds
31
what is the quaternary structure of a protein?
several proteins with a tertiary structure bind together to form the final protein
32
typically, how many protein subunits make up a quaternary protein?
Most quaternary proteins are made up of eight or less protein subunits, each contributing a specific structure and function to that protein
33
what are protein subunits?
tertiary structure proteins that make up the quaternary structure are typically referred to as protein subunits
34
when is a protein denatured?
A protein is denatured when it loses its folded three-dimensional structure - change in structure also alters the protein’s function
35
how does digestion denature protein?
acid in our stomachs unfolds protein units, allowing enzymes to work on the primary structure of a protein, separating off amino acids for absorption
36
what factors can denature protein and give examples
Heat, acid and agitation
Ex: cracking an egg on a heated frying pan, adding lemon juice to ceviche or beating egg whites
37
what is the protein digestion pathway in the body?
Mouth: no chemical digestion, only mechanical
Stomach: HCL acid denatures proteins; pepsin chemically digests protein
Pancreas: secretes pancreatic proteases (chymotrysin/trypsin)
Small Intestine: majority of digestion; pancreatic proteases chemically digest protein
Large Intestine: minimal protein digestion
38
the main site of protein digestion is the small intestine. what occurs here?
proteases trypsin and chymotrypsin, secreted by pancreas, act on remaining polypeptide structures. Proteases act on different amino acid sites to further break polypeptides into single, double (dipeptides) or triple (tripeptides) amino acids. All 3 are absorbed through active transport into centre of small intestine villus. Once amino acids enter villus, they pass into bloodstream via capillaries and proceed to liver. Amino acids that are not metabolized at liver are released into general blood circulation. Tissues can then pick up amino acids from blood and use them for various functions
39
what is the importance of protein to body structure?
bones, muscles, skin as well as every organ in the body contain protein
40
Key Structural Protein:
what is Collagen?
protein found in bone, skin and connective tissue; most abundant protein in humans and other mammals.
41
what does collagen do in bones?
collagen organizes itself into a rigid matrix that calcium and phosphate then harden
42
what does collagen do in skin?
collagen promotes firmness and strength
43
Key Structural Protein:
what is Elastin?
adds elasticity and can allow a structure to be slightly deformed and then resume its shape
44
what body part has both collagen and elastin?
outside portion of our ears have both collagen and elastin. Collagen allows the outer ear to maintain its shape, while elastin permits its flexibility
45
what is blood protein hemoglobin?
blood protein hemoglobin picks up oxygen at our lungs and delivers it where it is needed
46
how does protein transportation occur?
- protein tracks that allow other proteins to “walk” along them, carrying things around the cell
- protein channels regulate movement into and out of the cell
47
T/F: After a reaction has occurred, enzymes maintain their structure
True,
After a reaction has occurred, enzymes maintain their structure and can go on to catalyze other similar reactions.
48
what are the functions of enzymes?
enzymes speed up the rate of cellular reactions by providing a site for reactions to occur
49
T/F: Most enzymes are proteins
True,
Most enzymes, like lipases, amylases and proteases are proteins
50
what are the two proteins responsible for our movements?
Myosin and Actin are muscle proteins that interact to shorten our muscles so they can move our skeleton
51
how does muscle contractions work?
millions of myosin proteins bind to acn chains and then kink their heads to shorten the overall muscle length
52
what is the relation between protein and fluid balance?
water is attracted to positive and negative charges of amino acids in blood proteins drawing water into bloodstream and out of extracellular space
53
Fluid Balance:
what can occur if blood proteins are low?
if blood proteins are low, fluid can build up in the extracellular space, leading to Edema
54
how does collagen in skin protect us from disease?
stopping infectious agents from entering and causing harm
55
what are antibodies?
Y-shaped proteins that stick to the outside of pathogens, promoting their removal and limiting the harm they can cause
56
T/F: Proteins are the best fuel source for the body
False,
provides 4kcal/g, minor source of energy
- wasteful to deaminate an amino acid to metabolized and generate ATP
- deamination creates ammonia which gets excreted as urea.
- body rather use all parts of an amino acid to make body proteins instead
57
T/F: Amino acids can only synthesize proteins
False,
amino acids can also be used to synthesize substances that are not classified as proteins.
Ex: Creatine, DNA, RNA and neurotransmitters dopamine and serotonin
58
what is the process of amino acids used as energy?
1) deamination of amino acids
2) Deamination removes nitrogen-containing amine group so remaining structure can form pyruvate, acetyl CoA or citric acid cycle intermediates
3) reactant of cellular respiration is formed depends on side chain of original amino acid before it was deaminated
59
Protein Deficiency:
What are the two main conditions associated with death/disability?
marasmus and kwashiorkor
59
T/F: There is currently no upper limit for protein consumption
True,
no upper limit for protein consumption because complications from excessive protein intake are uncommon in the general population
60
Protein Deficiency:
What is Marasmus?
- wasting syndrome
- occurs when energy from energy and protein are deficient
61
Protein Deficiency:
What are the symptoms of Marasmus?
very low body weight, body temperature dysregulation, anemia, dehydration and heart irregularities
62
Protein Deficiency:
What is Kwashiorkor?
protein malnutrition associated with inadequate protein intake when energy needs are sufficient
63
Protein Deficiency:
What are the symptoms of Kwashiorkor?
evidenced by a distended, swollen abdomen and swollen legs and feet, but an otherwise slim appearance
64
How can protein promote a caloric deficit?
- protein rich foods promote fullness to consume less
- More calories are required to digest and absorb protein as compared to carbohydrates and lipids ==> higher thermic effect
- amino acids contribute to carb and lipid metabolism
65
what is the primary dietary factor that promotes weight gain?
a caloric intake that is consistently above the body’s needs
- high/low protein diet leads to weight gain depends on total calories consumed
66
Muscle protein synthesis increases in the 24 hours following resistance training. How does dietary protein help facilitate this process?
10 g of essential amino acids from protein in the first two hours after exercise encourages muscle growth
Ex: milk-based protein increase muscle strength and improve body composition
67
Athletes have higher protein requirements so how much should athletes increase their protein intake?
increase their protein intake from 0.8 g/kg body weight to 1.2–2.0 g/kg body weight, depending on the intensity and load of training to support muscle and metabolic adaptation and repair
68
What is the main bone protein?
Collagen, about half of the volume of bone and a third of its mass is composed of protein
- structural matrix that calcium and other minerals bind to and harden
69
high protein diets can promote what?
While protein is essential for bone structure, a high-protein diet has been associated with calcium excretion
70
T/F: High protein diets do not seem to negatively affect bone health
True
71
how does high protein diets impact the health of kidneys?
Filtration rates at kidney increase following dietary intake of protein due to kidneys working harder to excrete the waste products produced
72
how can patients with reduced kidney function decrease risk of further kidney decline?
avoiding potential negative effects of excessively low protein intake, by consuming 0.8 g/kg body weight of protein per day ==> aligns with the daily recommendation for protein
73
what are the two factors for protein quality?
1) how well a protein is absorbed/digested
2) how the types and quantities of amino acids in that protein source match the body’s requirements
74
Assessing Protein Quality:
Explain the Protein Digestibility Corrected Amino Acid Score (PDCAAS)
- industry standard for assessing protein quality
- compares amino acid content of a food against a standard amino acid profile. The highest score that can be achieved is 1.0
75
Assessing Protein Quality:
Explain the Digestible Indispensable Amino Acid
Score (DIAAS)
- measures how well amino acids are digested in the ileum and more closely estimates the amount of amino acids absorbed by the body
- database is still being built
76
Assessing Protein Quality:
Explain the Protein Efficiency Ratio (PER)
- how much weight an animal gains when consuming a specific amount of protein, divided by the amount of food it consumed
- system used in Canada
77
Give examples of processed protein supplements and extra whole food supplementation
Processed: protein powders, shakes and bars
Whole Food: animal products, milk and tofu
78
T/F: Supplementation beyond 1.62 g/kg body weight per day did not produce further gains
True,
protein supplementation may improve muscle-related gains, but only up to a certain amount of protein intake, and both whole and processed protein sources can provide this gain
79
what are Branched-chain amino acids (BCAAs)?
essential amino acids that have a branched side chain
80
Branched-chain amino acids (BCAAs) are key components of what?
key components of the amino acid pool, accounting for 35–40% of the dietary essential amino acids that are found in body protein
80
T/F: BCAAs have been shown to reduce muscle damage associated with weight training
True,
especially if consumed before exercise
81
what are the benefits of animal sources of protein?
- more total protein, a higher PDCAAS, are complete sources of protein, with all essential amino acids
- higher in vitamin B12, vitamin D, iron, zinc and omega-3 fatty acids
82
what are the disadvantages of animal sources of protein?
- higher in saturated fat, absent in fibre, and phytochemicals.
- consuming processed animal products (bacon, deli meat, sausage, red meat) increase CVD risk/mortality
83
what are the environmental impacts of consuming animal products?
- more water/land used to raise animals than to grow plants
- animals, especially larger ones, emit greenhouse gas methane through burps and flatulence
84
what is omnivore?
a person who consumes a variety of both animal and plant products
85
what is semi-vegetarian?
person who restricts one or more type of animal product.
Ex: a semi-vegetarian might avoid all red meat
86
what is pescatarian?
person who restricts most or all animal products except fish
87
what is a plant-based diet?
diet that mostly/entirely based on plant-derived foods and ingredients.
- vegetarian and vegan diets are plant-based
88
what is vegetarian?
person who avoids some or all-animal related food and ingredients
89
what is lacto-ovo vegetarian?
person who avoids animal flesh, but consumes milk products (lacto) and eggs (ovo)
90
what is lacto-vegetarian?
person who avoids animal flesh and eggs, but consumes milk products
91
what is vegan?
person who excludes all animal products (eggs/milk). may also include any animal-involved products (honey)
92
what are the health benefits of vegetarian diets?
- high in fibre, and phytochemicals and low in saturated fats
- lower BMIs, total cholesterol and LDL
- lower risk for heart disease, cancer and CVD mortality
93
what are the risks of vegetarian diets?
- lower in vitamin D, omega-3 fatty acids, calcium, iron, and zinc
- vitamin B12 only found in animal products (except nutritional yeast
- supplementation is recommended
94
T/F: Pregnant women have higher protein needs
True,
DRI is 1.1 g/kg body weight
95
why do children and infants have higher protein requirements?
to support their growth and development
96
T/F: Non-essential amino acids are not used to make body proteins
False, they are equally important in the body, but they are not required from the diet because the body can make them itself
97
T/F: All polypeptides are proteins
False, they have to fold in a specific fashion to be considered functional proteins
98
T/F: All proteins are polypeptides
True
99
T/F: In order for mutual complementation to provide sufficient essential amino acids, the sources of complementing proteins must be consumed at the same meal
False,
those that consume a plant-based diet can meet protein needs by eating a variety of plant protein sources; these do not have to be consumed at the same meal
100
T/F: High-protein diets are more likely to promote a caloric deficit than high-carbohydrate diets
True
101
T/F: Protein intake following resistance training can help promote muscle adaptation and repair
True
102
T/F: Protein supplements are more effective than whole sources of protein for promoting muscle growth and repair
False
103
In Canada, __________________ is used to measure the protein quality of food
Protein Efficiency Ratio (PER)
103
__________________ occurs when both energy and protein are deficient in the diet
Marasmus
104
T/F: Diets high in branched-chain amino acids are more likely to promote larger increases in muscle mass
False,
BCAAs have only been shown to improve recovery, not overall muscle mass
105
Which micronutrient is most likely to be inadequate in a vegan diet?
Vitamin B12
106
Based on body weight, what is the protein recommendation for those 18 years of age and older?
protein recommendation is 0.8 g/kg body weight per day
