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Basic structure of AA
- Central carbon
- Amino group
- Carboxylic acid group
- Hydrogen
- Side chain (R group)
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How many essential AAs?
9
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How many nonessential AAs?
11
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Example of when AA becomes essential
- Ppl w/ Phenylketonuria which prevents phenylalanine from being converted to tyrosine (phenylketones build up in brain), causing tyrosine to become essential
- (phenylalanine found in aspartame and proteins)
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Structure of protein
AA linked together, forming peptide chain
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AAs become linked by a _____ rxn, forming a peptide bond b/w 2 AAs
Condensation
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Protein Shape
Primary:
Secondary:
Tertiary:
Quaternary:
- 1: sequence of AAs
- 2: localized folding (alpha-helix, beta-pleated sheets)
- 3: higher level interactions
- 4: interaction of diff polypep chains
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Sickle cell disease: during DNA synthesis, ___ codon is converted to ____ codon (mutation). Can block capillaries, causing pain & inflammation b/c rb cells easily rupture, leading to low rb count & anemia
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4 methods of protein denaturation
- heat
- acid
- mechanical force
- salt (interacts w/elec chrgs)
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3 main structural functions of proteins
- Bone & tooth matrix
- Collagen
- Muscle fibers
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Proteins are needed to make:
- Body structures (bone, collagen, muscle)
- Enzymes
- Hormones
- Antibodies
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Proteins play a role in fluid balance inside cells (____), b/w cells (____), and in bloodstream (___).
- intracellular
- interstitial
- vascular
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Vacular proteins attract water and hold fluids in vascular system and are also known as
albumin
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Low protein & excess protein loss results in (4)
- kidney disease
- large wounds/burns
- inadequate protein synthesis
- liver disease
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Proteins are buffers, so important in maintaining
acid/base balance; pH balance
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What are examples of protein being involved in transport? (3)
- Hemoglobin (move oxygen around)
- Lipoproteins
- Membrane pumps
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Conversion of an amino acid from one compound to another
Transamination
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Removal of protein group
Deamination
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Product of deamination which can be used to make another AA via transamination
Keto acid
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NH2--> NH3--> urea
which part takes place in liver?
NH3--> urea
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Protein is __% nitrogen
16
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What groups of ppl have positive nitrogen balance (intake > output; N is being retained) (4)
Growing ppl: children, pregnant women; those increasing muscle growth; those recovering from illness
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RDA protein
Adults: ___ g per kg body weight per day
Infants (0-6 mo): ____ g per kg body weight per day
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AMDR protein: ___ to ___%
DV protein: ____ g
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How to Calculate Nitrogen Balance
143 lb / 2.2 = 65 kg
65 kg x .8 g = 52 g protein per day
52 g protein x .16 = 8.32 g nitrogen intake
Given: 10.3 g nitrogen output
8.32 g - 10.3 g = -2 g negative nitrogen balance
- Divide lb by 2.2 to get kg
- Multiply by .8
- Multiply by .16
- Input- Output = N balance
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Type of protein which contains all essential AAs and types of foods which contain all
Complete protein; animal & soy proteins
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Type of protein which lacks 1 or more essential AA and 2 examples
- Incomplete
- plants, gelatin
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Essential AA which is present in lowest amts compared to needs and limits the protein's use in synthesis of body protein
Limiting amino acid
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Measures of protein quality often factor in the protein's
digestibility
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Type of measure of protein quality which gives numerical grade which compares essential AA composition to reference protein (eg egg) and does not factor in digestibility
Chemical AA score
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Measure of protein quality
- Chemical AA score
- Biological Value (BV)
- Protein Efficiency Ratio (PER)
- Protein-Digestibility-Corrected Amino Acid Score (PDCAAS)
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Type of measure of protein quality which meaures N retention in animals fed test diet to determine if supports human growth if it's the sole dietary protein
Biological Value
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What is the biological value which supports human growth if it's the sole dietary protein?
>70
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Type of measure of protein quality which measures weight gain in animals fed test diet protein and which is used for protein comparison on infant formula and baby foods
Protein Efficiency Ratio (PER)
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Type of measure of protein quality which compares essential AAs to needs and is adjusted for digestibility; used to determine % DV; used to determine FDA standard for food protein quality
Protein-Digestibility-Corrected Amino Acid Score (PDCAAS)
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How to determine PDCAAS if .7 is AA score and .8 is digestibility score
.7 x .8 = .56
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Type of vegetarian who eats no red meat (beef, pork)
Semi-vegetarian
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Vegans must monitor intake of:
AA/complementary proteins
Vit ___
Vit ___
Calcium
Iron- maybe
Zinc- maybe
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Form of severe protein-energy malnutrition which results in muscle & fat wasting, poor growth, little disease resistance, slowed metabolism, impaired brain dvlpmt; "normal" response to starvation
(chronic)
Marasmus
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Form of protein-energy malnutrition which results in poor growth, low blood albumin (which affects fluid balance-liquid accumulates in extracellular space, causing edema), little disease resistance, apathy, withdrawal; "abnormal" response to starvation; "disease of 1st child when 2nd child is born"
(b/c put 1st child on grains when 2nd child born)
(acute)
Kwashiorkor
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Probs of excess protein intake (3)
- Risk of bone loss if calcium intake is inadequate
- Association b/w high meat intake and colon cancer
- Potential for dehydration from extra N to excrete
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Endurance athletes need ___ to ___ g/kg/day
Strength athletes need up to ___ g/kg/day
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Protein Digestion Overview
Mechanical digestion in ___
____ and ____ in stomach
_____ enzymes, then
_____ enzymes.
Absorbed as individual ____, or ____ or _____ into bloodstream
- mouth
- pepsin, HCL
- pancreatic
- brush-border
- AAs, dipeptides, tripeptides
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After deamination, some AAs are used to make 3 C compounds to make ____, and some are used to make ___ to go on to the ___ or to be converted to ____ and stored
- glucose
- acetyl coA
- Citric Acid Cycle
- FAs
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