Human Nutrition - Chapter Seven

Chemical structure of a protein

a carbon atom that anchors a hydrogen atom and three different groups of atoms: the amino or nitrogen containing group, the R group, and the carboxylic acid group

albumin

a protein in blood that helps to maintain the proper distribution of fluids in the blood and body tissues

edema

accumulatio of fluid in tissues - can happen during starvation when the level of protein in the blood decreases and some water then leaks out of the bloodstream

celiac disease

autoimmune disorder in which a person's immune system reacts to gluten resulting in damage to intestine and poor absorption

nitrogen balance

balancing nitrogen intake and protein turnover with losses

blood urea nitrogen

blood test used to assess kidney function; elevated level occurs when kidneys cannot filter urea from the blood properly

Functions of proteins

build new cells and many functional components of cells, component of hardened structures such as hair and nails, as enzymes, lubricants, clotting components, antibodies, compounds that help maintain fluid and pH balance, transporters, hormones, energy source as a last resort

carboxylic acid group

carboxylic acid portion of a compound

Phenylketonuria

cells are unable to produce active phenylalanine hydroxylase enzyme so phenylalanine and its toxic by products build up in tissues and damage cells

inborn error of metabolism

change in the normal DNA sequence of a gene

secondary structure

coiling of the polypeptide chain due to chemical attractions between certain components of the amino acids

amino

portion of an amino acid that contains nitrogen

food provocation test

prior, the patient eliminates the food from their diet for 3 weeks, then the provoking food is given and symptoms are noted

How do proteins act as a buffer?

protein molecules bind to H+ or to OH-

susceptibility to food allergies is influenced by

timing and does of initial allergen exposure, gut microbial dysbiosis, vitamin D status, omega 3 fatty acid intake, and antiacid use

food allergies effect ___% of the population

10

How much protein in a typical adult?

10-35% of energy from protein; 0.8 g/kg body weight

nonessential amino acids

11 of the 20 amino acids that a healthy human body can make

The human body contains about ____ of its amino acid supply from endogenous sources and the remainder from exogenous (dietary) sources

2/3

the human body contains proteins made from __ different amino acids

20

high protein diet

20-35% of total calories

in general, most plant foods provide less than ___ of protein per ounce

3g

essential amino acids

9 of the 20 amino acids that must be supplied by foods because the body cannot synthesize them or make enought to meet its needs

high quality proteins

complete proteins that are well digested, absorbed, and used by the body

proteins

complex organic molecules that contain carbon, hydrogen, and oxygen atoms like lipids and carbohydrates. They also contain nitrogen

common reasons for elevated Blood urea nitrogen

congestive heart failure, high protein intake, GI bleeding, heart attack, kidney disease, shock

peptide bond

connection between two amino acids; between the acid group of one amino acid and the amino group of another that release a water molecule when bonded

polypeptides

contain two or more amino acids

complete protein

contains all essential amino acids in the proper proportions that promote the deposition of protein in muscles and other tissues; primarily animal foods

incomplete protein

contains inadequate amounts of one or more of the essential amino acids

amino acid derivates

creatine, melanin, and regulatory amines - serotonin, epinephrine, and histamine

Effects of protein energy deficiency in children

do not grow well, weak, irritable, dehydration, infections, stunted growth, lower integlligence

protein complementation

eating combinations of certain plant food protein sources that together contain a proportion of amino acids similar to complete proteins from animal sources

marasmic kwashiorkor

edema and wasting

non celiac gluten sensitivity

emerging disorder - an intolerance to gluten containing foods in the absence of celiac disease or wheat allergy - causes IBS like symptoms

limiting amino acids

essential amino acids that are in relatively low amounts

tertiary structure

final three dimensional form of the protein

sickle cell anemia

genetic condition characterized by abnormal red blood cells - wrong amino acid is added to two of the polypeptide chains in hemoglobin; impairs hemoglobin's oxygen carrying ability

Where does protein digestion start?

in the stomach when HCl denatures proteins and converts inactive pepsinogen to pepsin

FODMAP intolerance

inability to digest the long chains of fructose

undernutrition

inadequate consumption of nutritious food

low quality proteins

incomplete and generally less digestible making their amino acids are less bioavailable

Where does the body get the info to make proteins

information coded in DNA

a food can be labeled as gluten free if

it contains less than 20 ppm

Risks with high protein diets

kidney damage in susceptible individuals, higher risk for CVD due to increase saturated fat diet, red meat and colon cancer are linked, osteoporosis

primary structure

linear chain of amino acids linked by peptide bonds

common reasons for low BUN

liver failure, inadequate protein, malnutrition, overhydration

negative nitrogen balance

loses more nitrogen than it retains; occurs during starvation, illness, and severe injury

protein energy malnutrition

malnutrition that occurs when the diet lacks sufficient protein and energy - children are susceptible

urine urea nitrogen

marker of protein intake

top food allergens in US

milk, eggs, fish, crustacean shelfish, tree nuts, peanuts, wheat, soybeans

antibodies

molecules that tag invading organisms for destruction by the immune system

transamination

nitrogen containing group is transferred to another substance to make a nonessential amino acid

creatinine

nitrogen containing waste produced by muscles

kwashiorkor

occurs where mothers breastfeed infants until they give birth to another child who is abruptly weaned to make way for the younger sibling - have stunted growth, unnaturally blond hair, swollen cheeks, arms, legs, and bellies

R group

part of an amino acid that determines its physical and chemical properties

after short peptides and amino acids enter absorptive cells,

peptides are broken down into amino acids and then travel to the liver via the hepatic portal vein; the liver keeps some amino acids and releases the rest into general circulation

amino acids

proteins are composed of smaller chemical units called amino acids

sources of complete proteins from plants

quinoa and soy

health advantages of high protein diet

reduce caloric intake, help retain lean muscle during weight loss, keep people full even when eating limited calories, enhance blood sugar regulation, improve blood lipid levels, and reduce blood pressure

carbon skeleton

remains of an amino acid following the removal of the amino group

deamination

removing the nitrogen containing group from an unneeded amino acid to make a carbon skeleton

positive nitrogen balance

retains more nitrogen than it loses as proteins are being added to tissues; pregnancy, infancy, and puberty, recovery from illness or injury, insulin, growth hormone, testosterone, weight training

What plant parts contain most protein?

seeds, tree nuts, legumes, and pods

conditionally essential

several nonessential amino acids that can become essential under certain conditions

marasmus

severe PEM; starvation - weakness and loss of body tissue mass

the shape of a protein is important because

structure determines function in the body

nutrigenetics

study of how inherited genetic variations influence the body's responses to specific nutrients and nutrient combinations

nutrigenomics

study of how nutrients affect the expression of a person's genome

protein turnover

the process of breaking down old or unneeded proteins into their component amino acids and recycling them to make new proteins, occurs continuously within cells

protein splitting enzymes that come from the pancreas into the small intestine

trypsin and chymotrypsin

quaternary structure

two or more polypeptide chains associating with each other to form large complexes

What happens if a person consumes more protein than they need?

undergo deamination and some of the excess NH2 goes to the liver as glutamate which is converted to ammonia which is converted to urea and exits the body as urine

denaturation

unfolding of protein - happens when protein is cooked

food intolerances

unpleasant physical reactions after consumin nonprotein foods