Human Nutrition: Proteins
polypeptides
10 or more groups
RDA for protein
10-15% of total calories, .8g protein per kg of healthy body weight ex: 70kgX.8g protein = 56 g protein per day
how many nonessential amino acids?
11
dipeptides
2 groups
how many amino acids are used to make protein?
20 different amino acids
tripeptides
3 groups
oligopeptides
4-9 groups
how many essential amino acids?
9
pepsin
active form
denaturation
alteration of a protein's three-dimensional structure, because of treatment by heat, enzymes, acid, alkaline solutions, agitation
building blocks of protein
amino acids
conditionally essential amino acid
amino acids made from essential amino acids if insufficient amounts are eaten
body makes proteins from?
amino acids we obtain from food
5 contributors of protein in us
beef, poultry, milk, white bread, & cheese - animal protein is 70% of our protein intake
limiting amino acid
body will only be able to make proteins if it has enough amino acids - importance of variety and balance!
functions of proteins
building blocks of body components, fluid balance and maintenance, acid/base balance, building blocks of hormones and enzymes, immune function, forming glucose, energy yielding, contributing to satiety
essential amino acids
cannot be made by humans in sufficient amount or at all, must be included in diet
protein synthesis: gene is expressed when?
cell makes protein
proteins linked together by?
chemical bonds called peptide bonds
protein synthesis: amino acids added one at a time as
code is "read" on ribosome (w/ aid of transfer RNA (tRNA)
protein digestion
cooking is useful in aiding digestion
DNA will not leave nucleus
copy made
egg to fried egg
denaturation from heat which results in alteration of the proteins 3-dimensional structure
dietary protein: low-quality (incomplete)
dietary proteins that are low in or lack one or more essential amino acid
dietary protein: high quality (complete)
dietary proteins that contain ample amounts of all nine essential amino acids
protein turnover
during any day, an adult makes and degrades about 250 grams of protein
protein synthesis: the protein synthesis steps require:
energy
limiting amino acid
essential amino acid in lowest concentration in food or diet relative to body needs
why people become vegetarians
ethics, religion, economics, health - can still meet nutritional needs as a vegetarian. Good for disease prevention, increases plant proteins in your diet
protein americans 2020
fat free and low fat milk products, variety of protein foods, increase amount and variety of seafood, replace protein foods high in solid fats
stomach and protein
gastrin hormone stimulates release of HCI and ultimately pepsin (enzyme to break down protein)
gluten sensitivity - celiac disease
gluten is protein found in certain grains, wheat, rye, barley - it is the incomplete breakdown in the small intestine
positive protein balance
growth, pregnancy, recovery stage after illness, injury, athletic training
protein equilibrium
healthy adult meeting nutrient needs, notably protein and calorie needs
health related to plant proteins
heart healthy, cancer-fighting, bone health, glucose control, soy and menopausal symptoms
plant sources
high fiber, limited saturated fat, contains no cholesterol
food protein allergies
immune system mistakes food protein for harmful invader, 8 protein foods account for 90% of food-related allergies (soy, peanuts, tree nuts, wheat, milk, eggs, fish and shellfish) reactions range from mild intolerance to fatal, introducing allergenic foods early in life may prevent allergies
pepsinogen
inactive form
proenzyme
inactive form of an enzyme - activated by HCI low PH in stomach - cleaves protein to smaller polypeptides
negative protein balance
inadequate protein intake, inadequate protein intake, fevers, burns, infections, increased protein loss
high protein diet
increased urine, can put strain on kidney, may increase calcium loss in urine
protein's final shape determines:
it's function in the body
order of amino acids in a protein determines:
it's ultimate shape, therefor order is very important
protein foods
legumes, beans, peas, peanuts, nuts and seeds - all contribute to protein, vitamin, fiber in meal
branched chain amino acids
leucine, isoleucine and valine (used by muscles for energy needs) - proteins from milk for strength training athletes
animal proteins
normally contain all 9 essential amino acids
amino acid supplements
not considered safe
plant proteins in grains
often low in one or more of the nine essential amino acids
most proteins are?
polypeptides 50-2000 groups
functions of protein
regulates and maintains body functions and provides essential form of nitrogen(in the form of amino acids)
hemoglobin abnormal sequence:
sickle cell anemia
protein digestion
small intestine peptide bonds broken down - small peptides and amino acids remain
protein-calorie malnutrition
somewhat rare in developed countries - examples kwashiorkor marginal calories insufficient protein, marasmus starvation of insufficient protein and calories
protein synthesis: copies of codes
transferred to the cytoplasm and ribosome (via mRNA)
complementary proteins
two food protein sources that make up for each other's inadequate supply of specific essential amino acids, together they yield a sufficient amount of all nine, so they provide high-quality (complete) protein when eaten together
protein absorption
what is being absorbed? small peptides and single amino acids