proteins Flashcards
proteins
-complex organic nitrogenous compounds made of C, H, O, N, and S
-essential
-20% of body weight
-polypeptides are made of polymerization of AA through peptide bonds
>50 aa=proteins
amino acids
composed of central C bonded to 4 groups
-amino gorup -NH2
-carboxyl group: -COOH
-Hydrogen
R group
essential AAs
9 essentials
-cant synthesize them in body
-Leucine
isoleucine
lysine
methionine
phenylalanine
threonine
valine
tryptophan
histidine
nonessential AA becoming essential
newborn, only 5 AA are non essential
metabolic pathways become more sufficient
protein structure
-primary: determine by sequence of AA (unchanged by denaturing)
-secondary: h bonding of peptide backcone
-tertiary: 3D pattern of a protein due to side chain interactions
-quat- multiple chains
classified by AA chains
dipeptide: 2
tripeptide: 3
polypeptide: more than 10
peptides: fewer than 50
proteins: more than 50
DandA mouth and stomach
Chewing in mouth (mechanical digestion)
-chemical digestion begins in stomach
-Gastrin stimulates release of HCL
-denautre proteins and activates pepsinogen to pepsin
DandA small intestine
Cholecystokinin (CCK)- peptide hormone of SI released from duodenal cells (stimulates digestion and stimulates release of pancreatic proteases)
-trypsin and chymotrypsin digest peptides to tri and di
-intestinal cells break them into amino acids
-absorbed through active transport
-transported to liver from the intestines by the hepatic portal vein
assimilation
in liver
-used to synthesize new proteins
-converted to glucose
-energy
-released to bloodstream
protein
4 cal/gram
-involved in blood clotting, fluid balance, hormone production, enzyme production, cell repair, connective tissues, neurotransmitters
Protein turnover
body constantly degrades proteins (300 pro) we only take in 65-90
-some are recycled to make new AA
-some are eliminated\
-some metabolized energy
Insulin and GH= increase protein synthesis
glucagon and cortisol= increase protein degradation
Deamination
removal of amine group
-loses an AA without transferring it to another molecule
-forms NH3
-C remanent=keto acid
-glucogenic=acid converted to glucose
ketogenic= acid to fats
-higher protein diets require more water
nitrogen balance
+N= intake is bigger than excretion
-N= intake less than excretion
zero N balance= equilibrium
transamination
forming NA AAs by transferring the N from one aa to a keto acid to form a new nonessential AA and a new keto acid
protein intake
RDA= 0.8g/kg/day
10-35%
digestibility
animal product= 90-99%
plant product= 70-90%
-soy and other legumes = >90%
Complementary proteins
2 or more incomplete protein sources that in combination compensate for each other’s lack of AA
high protein diet health effects
heart disease
cancer of colon, breast, kidneys, pancreas, and prostate
adult bone loss
Kawshiorkor (protein energy malnutrition)
-severe protein deficiency from diet high in grains
-edema in legs, feet and stomach
-low muscle
-brittle hair-increase infection
-water and electrolyte imbalance
Marasmus (protein energy deficiency)
severe deficiency in calories
-frail
-cannot stand
-older looking
-low Tb
-prone to dehydration
