NTR 213 - CHAPTER 6 : Proteins

what percent does protein make up in the human body

20%

chemical composition of protein

• carbon

• hydrogren

• nitrogen

• oxygen

• side chain (unique to each amino acid)

side chain..

• also called the R group

• structure determined by amino acid side chain

• determines chemical properties

  • non polar (hydrophobic)

  • polar (hydrophilic)

  • basic (positive charge

  • acidic (negative charge)

essential vs nonessential

essential

• body cannot make, must come from diet

• 9 essential amino acids

• PT MTV HILL

  • phenylalanine

  • threonine

  • methionine

  • tryptophan

  • valine

  • histidine

  • isoleucine

  • lucine

  • lysine

• 11 nonessential

proteins building blocks..

• amino acids are building blocks

• 20 amino acid in protein

conditionally essential

nonessential amino acids that become essential under certain circumstances

• phenylalanine (essential) makes tyrosine (nonessential)

• if body fails to make phenylalanine, tyrosine becomes essential

different type of proteins

animal based

• meats

  • beef

  • poultry

  • pork

  • fish

• products

  • dairy

  • eggs

plant based

• grains

• nuts

• legumes

  • seeds in beans or peas

animal protein high in..

• vtiamin d

• iron

• zinc

• calcium

• saturated fats

plant protein high and low in…

high in

• fiber

low in

• zinc

• calcium

• vitamins

• iron

peptide bonds

amino (positive) combined with acid (negative) creates peptide bonds

• dipeptide: 2 amino acids

• tripeptide: 3 amino acids

• polypeptide: many amino acids

shape=function

• elongated shape+collagen = strength to tendons and ligaments

• spherical shape+hemoglobin= carries oxygen in red blood cells

• linear shape+muscles= allows muscles to contract

denaturation

• breakdown of protein when exposed to abnormal environments

• protein folds unravel and become strands of amino acid

• because shape=function, once it unfolds, it no longer performs its function as before

  • agitation: stirring

  • heat: cooking

  • acidic and basic: low and high pH

digestion

begins in

• mouth (mechanical)

  • chewing

goes to

• stomach (chemical)

  • HCL: denatures large proteins so digestive enzymes can access them easier

  • pepsinogen: activated by HCL into pepsin → hydrolyzes peptide bonds in polypeptide chains (makes large proteins, smaller)

then goes to

• small intestine

  • pancreatic proteas and peptidases: break peptide bonds creating di and tripeptide

    • di and tri peptides and single amino acids are then absorbed by intestinal cells

    • microvillis further breakdown di and tripeptides into single amino acids

    • then they are transported to portal vein to the liver

amino acid pool

amino acids are not stored

• once digested, amino acids go to liver (liver uses some) then releases rest into bloodstream (the ‘pool’)

• tissues then take amino acids from the ‘pool’ as needed

• when there are too much amino acid in the pool, excess amino acids go through deamination (nitrogen removal) and remaining carbon skeleton is used for energy or converted to fat for storage

additional use of amino acid

• protein (main use)

• nucleotides for DNA and RNA

• neurotransmitters: helps nerves communicate

protein synthesis

making protein from amino acids

• DNA has genetic information

• genes get a portion of DNA w/ instructions

• transcription copies the information from gene the mRNA

• translation attached to ribosome, where genetic codes are translated and ribosome joins amino acids in correct order to make protein

• gene expression is the whole process of cells using genes to make proteins

  • transcription and translations are steps to this process

protein functions in the body

• enzymes

  • provide place for chemical reactions

  • speed up chemical reaction

• structural component

  • builds and support cells

• transports proteins

• movement: muscle contractions

• immunity: protects body from foreign invaders

• hormones: chemical messenger

• fluid balance: keeps right amount of water in blood and tissues

nitrogen balance

• negative: breaking down protein more than making

  • starvation

  • infection

  • wound healing

• positive: making more protein than breaking down

  • gaining body weight

  • pregnancy/lactaction

protein quality

• high = complete

  • contains all 9 essential amino acids

  • from animal or soy protein

  • easily digested

• low = incomplete

  • low in one or more essential amino acid

  • not easily digested

  • plant proteins

    • use complementary protein: 2 incomplete protein makes a complete protein

      • rice and beans or sandwich and peanut butter

protein dietary recommendations

ADMR

• for health adults: 10-35% of total intake should be from protein

RDA

• for health adults: 0.8g/kg of body weight per day

  • minimum need for repair in body

vegan risks

• protein deficiencies

• vitamin/mineral deficiences

  • iron

  • zinc

  • calcium

  • vitamin b

excessive protein intake

• from animal sources

  • cardiovascular diseases

  • type 2 diabetes

  • cancer

• from plant sources

  • no negative outcomes