nutrition chapter 6

proteins

oxygen, and nitrogen and arranged as strands of amino acids. (Some amino acids also contain the element sulfur.

amino acids

the building blocks of protein

• each has an amine group at one end, an acid group at the other, and a distinctive side chain

amine group

the nitrogencontaining portion of an amino acid.

side chain

the unique chemical structure attached to the backbone of each amino acid that distinguishes one amino acid from another

essential amino acids

amino acids that either cannot be synthesized at all by the body or cannot be synthesized in amounts sufficient to meet physiological need

• there are 9 essential

• there are 11 non essential

conditionally essential amino acid

an amino acid that is normally nonessential but must be supplied by the diet in special circumstances when the need for it exceeds the body’s ability to produce it

• there are 7, including tyrosin

peptide bond

a bond that connects one amino acid with another, forming a link in a protein chain.

• a strand of amino acids

polypeptide

a protein fragment of about 10 to 50 amino acids bonded together

collagen

the chief protein of most connective tissues, including scars, ligaments, and tendons, and the underlying matrix on which bones and teeth are built

enzymes

proteins that facilitate chemical reactions without being changed in the process; protein catalysts.

hemoglobin

the globular protein of red blood cells, whose iron atoms carry oxygen around the body via the bloodstream

sickle-cell disease

a genetic form of anemia characterized by abnormal sickle- or crescent-shaped red blood cells, which interfere with oxygen transport and blood flow.

RNA

cellular nucleic acids that play key roles in the process and control of protein synthesis

nutritional genomics

the science of how food components, such as nutrients, interact with the body’s genetic material

denaturation

the irreversible change in a protein’s folded shape brought about by heat, acids, bases, alcohol, salts of heavy metals, or other agents.

dipeptides

protein fragments that are two amino acids long

tripeptides

protein fragments that are three amino acids long

protein turnover

the continuous breakdown and synthesis of body proteins involving the recycling of amino acids

catalyst

a substance that speeds the rate of a chemical reaction without itself being permanently altered in the process.

• All enzymes classify as this

hormones

chemical messengers secreted by a number of body organs in response to conditions that require regulation.

• Each one affects a specific organ or tissue and elicits a specific response

thyroxine

a principal peptide hormone of the thyroid gland that regulates the body’s rate of energy use

serotonin

a compound related in structure to (and synthesized from) the amino acid tryptophan.

• serves as one of the brain’s principal neurotransmitters

antibodies

large proteins of the blood, produced by the immune system in response to an invasion of the body by foreign substances (antigens)

• combine with and inactivate the antigens.

immunity

protection from or resistance to a disease or infection by the development of antibodies and by the actions of cells and tissues in response to a threat

fluid and electrolyte balance

the proper distribution of fluid and dissolved particles (electrolytes) among body compartments

edema

swelling of body tissue caused by leakage of fluid from the blood vessels

• can occur during significant protein deficiency

acids

compounds that release hydrogens in a watery solution

bases

compounds that accept hydrogens from solutions

acid-base balance

equilibrium between acid and base concentrations in the body fluids.

buffers

compounds that help keep a solution’s acidity or alkalinity constant

acidosis

the condition of excess acid in the blood, indicated by a below-normal pH

alkalosis

condition of excess base in the blood, indicated by an above-normal blood pH

urea

the principal nitrogen-excretion product of protein metabolism; generated mostly by removal of amine groups from unneeded amino acids or from amino acids being sacrificed for energy.

gelatin

a protein product of collagen breakdown

• In foods, it confers structure, such as in gelatin desserts

• in nutrition, it supplies low-quality protein that lacks certain essential amino acids.

nitrogen balance

the amount of nitrogen consumed compared with the amount excreted in a given time period.

high-quality proteins

dietary proteins containing all the essential amino acids in relatively the same amounts that human beings require. They may also contain nonessential amino acids.

limiting amino acids

an essential amino acid that is present in dietary protein in an insufficient amount, thereby limiting the body’s ability to build protein

complementary proteins

two or more proteins whose amino acid assortments complement each other in such a way that the essential amino acids missing from one are supplied by the other

legumes

plants of the bean, pea, and lentil family that have roots with nodules containing special bacteria that trap nitrogen from the air in the soil and convert it into a form that becomes part of the plant’s seeds.

• The seeds are rich in digestible protein compared with most other plant foods.

red meats

flesh foods that appear red when raw due to the iron-containing compounds in muscle; meat from cattle, pigs, sheep, goats, deer, and other large animals

processed meats

a general term for meat products preserved by smoking, curing, salting, or adding chemical preservatives—for example, ham, bacon, jerky, hot dogs (including chicken and turkey), deli meats, salami, and other sausages

gluten

a type of protein in certain grain foods. Individuals with celiac disease experience a damaging immune response in the small intestine after consuming gluten

celiac disease/gluten-sensitive enterpathy/celiac sprue

a disorder characterized by an abnormal immune response, nutrient malabsorption, weight loss, and intestinal inflammation on exposure to the dietary protein gluten

non-celiac gluten sensitivity

a unclearly defined collection of digestive symptoms that improves with elimination of gluten-containing foods from the diet.

textured vegetable protein

processed soybean or other plant-based protein used in products formulated to look and taste like meat, fish, or poultry

tofu

a curd made from soybeans that is rich in protein, often enriched with calcium, and variable in fat content; used in many Asian and plant-based dishes

plant-based diet

an eating style consisting largely of healthful vegetables, grains, legumes, fruit, and nuts

• may or may not include limited amounts of animal products, such as meats, fish, poultry, and dairy

flexitarian/partial vegetarian/semi vegetarian

a predominantly plant-based diet, with occasional inclusions of meat, poultry, or fish

• tasks

• collagen, enzymes, and hemoglobin

• association

variety of proteins:

• Protein shapes enable performance of different ___

• Examples are ___, ___, and ___

• Some protein strands work alone, while others need ____

• denatures

• enzymes

• polypeptides

• dipeptides … tripeptides

protein digestion:

stomach

• Hydrochloric acid ___ protein in food by uncoiling protein’s strands

• ___ attack peptide bonds

Small intestine

• Proteins enter as ___

• Further break down to ___ and ___

• small intestine

• hormones … allergies

• absorption

• bloodstream … liver

amino acid absorption:

• Absorbed by cells of ____________

• Larger molecules can act as _________ and play a role in food _________

• Cells have separate sites for ___________ based on types of amino acids

• Once amino acids are circulating in the __________-, they are carried to the _________ or used or released into blood for use by other cells.

• acid-base balance: Proteins help maintain the acid–base balance of various body fluids by acting as buffers

• antibodies: Proteins form the immune system molecules that fight diseases.

• blood clotting: Proteins provide the netting on which blood clots are built.

• energy and glucose:Proteins provide some fuel for the body’s energy needs.

• enzymes: Proteins facilitate needed chemical reactions

• fluid and electrolyte balance: Proteins help to maintain the water and mineral composition of various body fluids

• gene expression: Proteins associate and interact with DNA, regulating gene expression.

• hormones: Some hormones are proteins or are made from amino acids

• structure and movement: Proteins form integral parts of most body tissues and confer shape and strength on bones, skin, tendons, and other tissues. Structural proteins of muscles execute body movement.

• transport: Proteins help transport needed substances, such as lipids, minerals, and oxygen, around the body

protein functions:

• acid-base balance

• antibodies

• blood clotting

• energy and glucose

• enzymes

• fluid and electrolyte balance

• gene expression

• hormones

• structure and movement

• transport

• Amino acids to glucose (Only some amino acids)

• Urea

• Breaking down protein tissue for amino acids

• Insufficient energy and/or carbohydrates and fat

• No storage form of protein exists in the body

• Excess amino acids

• Used to meet immediate energy needs, to make glucose for storage as glycogen, and to make fat or energy storage

protein as an energy source

• 0.8

• 10-35

• growth

• healing

• malnutrition or infection

• 1.2-1.7

How Much Protein Do People Need?

• DRI: ______ g/kg of body weight

• AMDR: _______-% of total calories

• Factors that influence protein needs

  • _________

  • __________

  • ___________

• Athletes: _______ to _______ gram per kilogram per day

positive nitrogen balance

nitrogen-in exceeds nitrogen-out

• pregnancy, growth spurts, growing children

• more proteins being built than broken down and lost

negative nitrogen balance

nitrogen-in is less than nitrogen out

• starvation and illness

• losing protein, protein tissue, or muscle

• heart disease … cancer

• red

• processed

effects of excess protein:

High-protein diets

• ___ and ___

• ___

• ___ meats

lacto-vegetarian

a diet that includes dairy products, vegetables, grains, legumes, fruit, and nuts; excludes flesh, seafood, and eggs

ovo-vegetarian

diet that includes eggs, vegetables, grains, legumes, fruit, and nuts, and excludes flesh, seafood, and milk products

vegan/strict vegetarian

a diet that includes only food from plant sources: vegetables, grains, legumes, fruit, seeds, and nuts

lacto-ovo vegetarian

a diet that includes dairy products, eggs, vegetables, grains, legumes, fruit, and nuts; excludes flesh and seafood.

benefits of plant based diets

help w/

• obesity

• heart and artery disease

• high blood pressure

• cancer

• type II DM

• cataracts, diverticular disease, gallstones, and osteoporosis