Chapter 6: Proteins

nonessential amino acids

amino acids that can be synthesized by a healthy body in sufficient amounts; there are 11 of these amino acids. these are also called dispensible amino acids.

conditionally essential amino acids

amino acids that must be made from essential amino acids if insufficient amounts are eaten

250 grams

an adult makes and degrades about this much of protein, recycling many of the amino acids.

sickle cell disease

an illness that results from a malformation of the red blood cell because of an incorrect structure in part of its hemogloboin protein chains. this is due from a defect in a person's genetic blueprint, DNA, inherited from one's parent.

buffers

are compounds that maintain acid-base conditions within a narrow range.

cell

every ______ contains proteins.

nuts and seeds

excellent sources of plant protein and make a powerful contribution to health when consumed in moderation.

plant proteins

except soy protein and quinoa seed, they do not match our need for essential amino acids. many of them are low in one or more of the nine essential amino acids.

denaturation

exposure to acid or alkaline substances, heat, or agitation can alter a protein's structure, leaving it uncoiled or otherwise deformed. this process is called

high-protein diets

increase urine output, in turn posing a risk for dehydration.

4 to 5 months of age

infants of this age gastrointestinal tract is somewhat permeable to small proteins, so some whole proteins can be absorbed.

protein turnover

is a process by which a cell can respond to its changing environment by producing proteins that are needed and disassembling proteins that are not needed.

three-dimensional structure of the intended protein

once synthesis of polypeptide is complete, it twists and fold into this

brain

only this can resists protein breakdown.

plant foods

per gram of protein, this provide more magnesium, fiber, folate, vitamin E, iron, zinc, and some calcium than animal sources of protein. as well as phytochemicals.

calories

plant foods contain fewer of this to the diet than most animal products.

poultry, fish, nuts, legumes, and seeds

some experts suggest that we focus on these food to meet protein needs.

essential amino acids

the amino acids that cannot be synthesized by humans in sufficient amounts or at all. and therefore must be included in the diet; there are nine of these amino acids. these are also called indispensable amino acids.

0.8 grams of protein per kilogram of healthy body weight

the best estimate for the amount of protein required for nearly all adults to maintain protein is

amino acids

the building block for proteins containing a central carbon atoms with nitrogen and other atoms attached.

messenger RNA

transfer code from the nucleus to the cytoplasm.

false (they all have the different chemical makeups)

true or false: all amino acids has the same acid group, amino group, and the same side or R group.

true

true or false: almost all enzymes are proteins or have a protein component.

true

true or false: body functions such as blood clotting, fluid balance, hormone, and enzyme production, visual processes, transport of many substances in the bloodstream, and cell repair require specific proteins.

true

true or false: energy input is required to add each amino acid to the chain, making protein synthesis "costly" in terms of calories use.

false (they can get it from all single animal protein)

true or false: humans are able to use proteins from only selected animal source efficiently to support growth and maintenance than from any single plant source.

false

true or false: if it lacks proper structure, a protein can still function.

true

true or false: if we do not consume enough calories to meet needs, proteins are broken down, allowing cells to harness the energy stored in proteins and rendering the amino acids unavailable to build body proteins.

true

true or false: in the case of food allergies, the immune system mistaken a food protein for a harmful invader.

true

true or false: in the liver, individual amino acids can undergo several modifications, depending on the needs of various body tissues.

false (it needs to be no more than just a day)

true or false: meeting amino acid needs over the course of a week is a reasonable goal because there is a ready supply of amino acids from those present in body cells and in the blood.

true

true or false: most of us consume much more protein than the RDA recommends because we like many high-protein foods and can afford to buy them.

true

true or false: proteins supply little energy and costly source of calories.

branched-chain amino acids

The R group on some amino acids has a branched shape, like a tree; such as leucine, isoleucine, and valine; they are primary amino acids used by muscles for energy needs, thus it is essential.

peptide bond

a chemical bond formed between amino acids to make proteins

kwashiorkor

a disease occurring primarily in young children who have an existing disease and consume a marginal amount of calories and insufficient protein in relation to needs. the child generally suffers from infections and exhibits edema, poor growth, weakness, and an increased susceptibility to further illness.

marasmus

a disease resulting from consuming a grossly insufficient amount of protein and calories; one of the diseases classed as protein-calorie malnutrition. victims have little or no fat stores. little muscle mass, and poor strength. death from infection is common.

pepsin

a major stomach enzyme for digesting proteins and break the polypeptide into shorter chains of amino acids because it can break only a few of the many peptide bonds found in these large molecules.

positive protein balance

a state in which protein intake exceeds related protein losses, as is needed during times of growth.

protein equilibrium

a state in which protein intake is equal to related protein losses; the person is said to be in protein balance.

negative protein balance

a state in which protein intake is less than related protein losses, as it often seen during acute illness.

gruels

a thin mixture of grains or legumes in milk or water.

protein-calorie malnutrition (PCM)

condition resulting from regularly consuming insufficient amounts of calories and protein. the deficiency eventually results in body wasting, primarily of lean tissue, and an increased susceptibility to infections. also known as protein-energy malnutrition.

high-quality proteins

contain sufficient amounts of the nine essential amino acids

protein

food and body compounds made of amino acids

cooking

it unfolds proteins and softens tough connective tissue in meat; makes protein-rich foods easier to chew and swallow, and facilitates their breakdown during later digestion and absorption. lastly, makes food safer to eat.

oligopeptides

joining of four to nine amino acids

polypeptides

joining of ten or more among acids

tripeptides

joining of thee amino acids

dipeptides

joining of two amino acids

lower-quality (incomplete) proteins

low or lack one or more essential amino acids.

breakdown, rebuilding, and repair

most vital body proteins are in a constant state of these

athletes and dieters

protein and amino-acid supplements are used primarily by these people

satiety

protein provide the highest feeling of this after a meal

cytoplasm

protein synthesis in a cell takes place in here. thus the DNA code used for synthesis of a specific protein must be transferred from the nuclues to here to allow for protein synthesis.

carbon, hydrogen. oxygen, nitrogen, and sometimes other atoms in a specific configuraton.

proteins are composed of

4 per gram kcal

proteins have this much kcal to supply energy.

acid-base balance

proteins help regulate this in the blood

ribosomes

read the mRNA code and translate those intrictions to produce a specific protein.

transfer RNA

responsible for bringing specific amino acids to the ribosomes as needed during protein synthesis

limiting amino acid

the essential amino acid in lowest concentration in a food or diet relative to body needs.

capillary beds

the presence of blood proteins in here attracts the proper amount of fluid back to the blood, partially counteracting the force of blood pressure.

hormone gastrin

the release of pepsin is controlled by; when thinking about food or chewing food stimulates this release in the stomach.

absorptive cells lining the small intestine

the short chains of amino acids and no individual amino acids in the small intestine are taken up by the active transport into here

beef, poultry, milk, white bread, and cheese

the top five contributors of proteins to be the north american diet have traditionally been

animal proteins

they contain ample amounts of all nine essential amino acids

alcoholism

this can lead to cases of protein deficiency because of the low protein content of alcoholic beverages that make up a high percentage of calories.

red meat

this is linked to colon cancer, cardiovascular disease, and other cancer.

genetic engineering

this may ultimately be able to correct many gene defects in humans by placing the correct DNA code in the nucleus so that the correct protein can be made by ribosomes.

11%

this much of our total recommended protein is all we need to be supplied by essential amino acids because typically 50% of the amino acids in dietary proteins are essential.

70%

this much of the protein we have come from animal sources

DNA

this present in the nucleus of the cell and contains coded instructions for protein synthesis.

true

true or false: some of the nonessential amino acids, which are usually synthesized in the body, can become essential during times of rapid growth, disease, or metabolic stress.

true

true or false: some researchers have expressed concern that a high-protein intake may overburden the kidneys by forcing them to excrete the extra nitrogen as urea.

true

true or false: the depletion of just one of the essential amino acids prevents protein synthesis, the process illustrates the all or none principle.

false (they are greater for growth and development)

true or false: the estimated requirement for essential amino acids for infants and prescholl are lower than adults.

false ( it's only 1.7 grams per kilogram)

true or false: the food and nutrition board does not support an increased need, but some experts suggest an increase to about 2.3 grams per kilogram.

true

true or false: the united nations food and agriculture organization (FAO) reports that in developing countries, milk consumption per person has almost double between 1980 and 2005, meat consumption increased fivefold. the greatest increases in consumption are occurring in east and southeast asia.

true

true or false: we do not need proteins themselves. we dismantle ingested dietary proteins and use the amino-acid building blocks to assemble the proteins we need.

false (it lacks the materials to function properly)

true or false: without sufficient dietary protein, the immune system has all the materials needed to function properly.

true

true or false: your body uses 20 different amino acids to function.

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 and so provide high-quality (complete) protein for the diet.

trypsin

when CCK travels through the bloodstream to the pancreas where it causes the pancreas to release protein-splitting enzymes, such as this and further divide the chains of amino acids into segments of two to three amino acids and some individual amino acids.

glucose

when a person do not consume enough carbohydrate to supply this, their liver will be forced to make it from amino acids present in body tissues.

amino-acid supplements

when individual takes this, they can overwhelm the absorptive mechanisms in the small intestine, triggering amino-acid imbalances in the intestinal tract.

cholecystokinin (CCK)

when partially digested proteins goes into small intestine from the stomach, it releases of this hormone from the walls of small intestine.

it does not have enough amino acids available to build the proteins it needs

why does our metabolic processes slow down when we consume inadequute amount of protein?

edema

with an inadequate consumption of protein, the concentration of protein in the bloodstream drops below normal. excessive fluid then builds up in the surrounding tissues. as fluid accumulate in the tissues, the tissues swell, causing this