Nutrition 211 - Chapter 6

Why is the daily general DRI for protein intake based on grams per kilogram of body weight?

0.8 grams for each kilogram

How many amino acids make up the majority of proteins?

20

How many amino acids are essential?

9

What is the recommended percent of total calories from protein according to the AMDR?

Acceptable intake range: 10 to 30% of calories from protein.

What can happen when an excess of a single amino acid is eaten

An excess of one amino acid can tie up a carrier and disturb amino acid absorption, creating a temporary imbalance

What food groups contribute to the typical American protein intake?

Beef, Poultry

What are some advantages to intake of plant protein?

Less calories, Legumes are also excellent sources of many B vitamins, iron, and other minerals, making them exceptionally nutritious foods

macrobiotic diets

a vegan diet composed mostly of whole grains, beans, and certain vegetables; taken to extremes, macrobiotic diets can compromise nutrient status.

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. Also called indispensable amino acids.

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.

limiting amino acid

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

fluid and electrolyte

balance maintenance of the proper amounts and kinds of fluids and minerals in each compartment of the body.

How do cells recycle amino acids?

breaks protein molecules apart and reuses those amino acids

How does the chemical charge of an amino acid affect protein structure?

can cause some segments of the strand to coil, somewhat like a metal spring

RNA (ribonucleic acid)

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

hormones

chemical messengers secreted by a number of body organs in response to conditions that require regulation. Each hormone affects a specific organ or tissue and elicits a specific response.

proteins

compounds composed of carbon, hydrogen, oxygen, and nitrogen and arranged as strands of amino acids. Some amino acids also contain the element sulfur.

bases

compounds that accept hydrogens from solutions.

acids

compounds that release hydrogens in a watery solution.

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.

acid-base balance

equilibrium between acid and base concentrations in the body fluids.

What makes an amino acid "essential"?

healthy adult body cannot make some amino acids or makes them too slowly to meet its needs. essential amino acids can be replenished only from foods

What happens to protein in the stomach?

hydrochloric acid produced by the stomach denatures proteins in food

What can happen if a protein sequence is altered?

if a wrong amino acid is inserted, the result can be disastrous to health

vegetarian

includes plant-based foods and eliminates some or all animal-derived foods.

How much protein is recommended during weight loss?

it is calorie intake reduction alone and not the proportion of energy nutrients in the diet that brings about long-term weight loss.

How is nitrogen excreted?

kidneys for excretion in the urine

antibodies (AN-te-bod-ees)

large proteins of the blood, produced by the immune system in response to an invasion of the body by foreign substances (antigens). Antibodies combine with and inactivate the antigens.

What food sources generally provide high quality proteins?

meat, fish, poultry, cheese, eggs, milk, and most soybean products

buffers

molecules that can help to keep the pH of a solution from changing by gathering or releasing H ions.

What atoms are found in all proteins, and which one of these atoms is not found in either carbohydrate or fat?

nitrogen atoms in addition to the carbon, hydrogen, and oxygen atoms. Nitrogen.

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.

polypeptide (POL-ee-PEP-tide)

protein fragments of many (more than 10) amino acids bonded together (poly means "many"). A peptide is a strand of amino acids.

tripeptides (try-PEP-tides)

protein fragments that are three amino acids long (tri means "three").

dipeptides (dye-PEP-tides)

protein fragments that are two amino acids long (di means "two").

enzymes (EN-zimes)

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

Does eating extra protein make muscles grow stronger? Explain

research suggests that well-timed protein intakes can often further stimulate muscle growth with exercise

edema (eh-DEEM-uh)

swelling of body tissue caused by leakage of fluid from the blood vessels; seen in protein deficiency (among other conditions).

nitrogen balance

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

What is protein-calorie malnutrition

the body slows its synthesis of proteins while increasing its breakdown of body tissue protein to liberate the amino acids it needs to build other proteins of critical importance

amino acids (a-MEEN-o)

the building blocks of protein. Each has an amine group at one end, an acid group at the other, and a distinctive side chain.

collagen (COLL-a-jen)

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

acidosis (acid-DOH-sis)

the condition of excess acid in the blood, indicated by a below-normal pH (osis means "too much").

alkalosis (al-kah-LOH-sis)

the condition of excess base in the blood, indicated by an above-normal blood pH (alka means "base"; osis means "too much").

protein turnover

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

denaturation

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

amine group

the nitrogen-containing portion of an amino acid.

hemoglobin (HEEM-oh-globe-in)

the oxygencarrying protein of the blood; found in the red blood cells (hemo means "blood"; globin means "spherical protein").

urea (yoo-REE-uh)

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

What is deamination?

the removal of an amino group from an amino acid or other compound

nutritional genomics

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

side chain

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

What happens if a person eats more protein than the body needs?

three ways: to meet immediate energy needs, to make glucose for storage as glycogen, or to make fat for energy storage

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.

What is the benefit of recycling amino acids?

Cells can also use the amino acids for energy and discard the nitrogen atoms as wastes. By reusing intact amino acids to build proteins, however, the body recycles and conserves a valuable commodity while easing its nitrogen disposal burden.

What foods contain low quality protein?

Corn, bread

What are the positive health aspects of a vegetarian diet?

Defense against Obesity, Defense against Heart and Artery Disease, Defense against High Blood Pressure, Defense against Cancer

How does amino acid charge affect function?

Electrically charged are attracted to water. Neutral repel water.

What additional factors can modify an individual's protein needs?

Factors concerning both the body and food sources modify an individual's protein need.

What are reasons people choose to become vegetarians?

Health concerns, Moral objections, Human treatment of animals

What other conditions and diseases have been correlated with high-protein intake?

Kidney Disease, Adult Bone Loss

Gluten (GLOO-ten)

a type of protein in certain grain foods that is toxic to the person with celiac disease.

How are amino acids hooked together to build proteins?

Peptide Bond

Provide examples of people in negative nitrogen balance

Person in surgery, astronaut

Provide examples of people in positive nitrogen balance

Pregnant woman, person growing muscle, child growing

How does protein intake impact the development of CVD?

Protein itself is not known to contribute to heart disease and mortality, but some of its food sources may do so.Footnote Selecting too many animal-derived protein-rich foods, such as fatty red meats, processed meats, and fat-containing milk products, adds a burden of saturated fat to the diet

What happens to polypeptides when they enter the small intestine?

Protein-digesting enzymes from the pancreas and intestine continue working until almost all pieces of protein are broken into single amino acids or into strands of two or three amino acids

celiac disease (SEE-lee-ack)

a disorder characterized by an abnormal immune response, weight loss, and intestinal inflammation on exposure to the dietary protein gluten; also called gluten-sensitive enteropathy or celiac sprue.

When can denaturation occur?

Proteins can be denatured by heat, acids, bases, alcohol, or the salts of heavy metals.

Summarize the functions of protein

Proteins help regulate gene expression; provide structure and movement; serve as enzymes, hormones, and antibodies; provide molecular transport; help regulate fluid and electrolyte balance; buffer the blood; contribute to blood clotting; and provide energy.

What is the disease associated with a sequencing error in hemoglobin?

Sickle-cell disease

What distinguishes each amino acid from other amino acids?

Side Chain

Where does absorption of amino acids take place?

Small Intestine

Where does the digestion of protein begin?

Stomach

How does the structure of a protein affect its function?

The particular shapes of proteins enable them to perform different tasks in the body

What is the function of stomach acid on protein digestion?

This acid helps to uncoil the protein's tangled strands so that molecules of the stomach's protein-digesting enzyme can attack the peptide bonds

serotonin (SER-oh-TONE-in)

a neurotransmitter important in sleep regulation, appetite control, and mood regulation, among other roles. Serotonin is synthesized in the body from the amino acid tryptophan with the help of vitamin B6

non-celiac gluten sensitivity

a poorly defined collection of digestive symptoms that improves with elimination of gluten from the diet.

thyroxine (thigh-ROX-in)

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

catalyst

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

Where do amino acids go after they have been absorbed?

Transported to the liver by the bloodstream

Under what circumstance will amino acids be used for energy?

Under conditions of inadequate carbohydrate or energy, protein breakdown speeds up

How digestible are protein supplements compared to protein foods?

Whole proteins are preferred

peptide bond

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