NUT Chapter 6

False

True

lysine, methionine, and threonine

can be used for protein synthesis

amino acids.

side chain

must be provided by the diet.

order of amino acids.

its shape and function.

nonessential proteins

nitrogen

False

Protein is absorbed as single amino acids or small peptide chains by the process of active transport.

False

the uncoiling of the protein molecule by hydrochloric acid in the stomach

All of the listed responses are correct.

HCl.

stimulate the release of HCl.

circulation in the blood as amino acids

deamination

is converted to urea and excreted through the urine

by transferring the amino group from one amino acid to a keto acid. A keto acid is an amino acid without the amine group.

False

a peptide bond

dipeptide

an oligopeptide

mRNA

gluconeogenesis

synthesizing more than 100,000 specific proteins.

body fat

They are biological catalysts that speed up reactions.

4 kcal/g.

supplies all the essential amino acids.

fruits

tofu

corn

chicken breast

Proteins from foods of animal origin are generally high-quality proteins.

kwashiorkor.

play essential roles in building and maintaining the body. Proteins are involved in most of the body's functions. differ structurally from carbohydrates and lipids. Excess dietary __________ cannot be stored in the body. is the only food component that provides nitrogen for the body.

There are 20 distinct ___________ Each contains a central carbon surrounded by four parts (a carboxyl, an amine group, a hydrogen atom, and a side chain). are joined to each other via peptide bonds (dehydration reaction). Peptides are split by hydrolysis.

amino acid chain made of less than 50 amino acids

2 amino acids joined by a peptide bond

3 amino acids joined by a peptide bond

more than 10 amino acids joined by a peptide bond

chain of more than 50 amino acids

Nine of the amino acids are essential—they cannot be made in the body.

11 are nonessential and can be synthesized in the body.

Some nonessential amino acids can become conditionally essential if the body cannot make them due to illness or because the body lacks the needed precursors or enzymes.

The order of amino acids in the polypeptide chain determines shape and function.

The straight amino acid chain bends into coils (alpha helices).

the amino acid chain with coils bends/folds onto itself.

Two or more polypeptide chains cluster.

changes their shape (untangles them)

Protein digestion begins in the stomach. HCl denatures protein and also converts pepsinogen to pepsin, which breaks polypeptides into shorter chains. Protein digestion continues in the small intestine. The pancreas secretes proteases, which continue the breakdown of peptide bonds into smaller peptide chains and single amino acids in the small intestine. Amino acids are absorbed in the small intestine. After reaching the liver, amino acids are used to synthesize new proteins or are converted to energy, glucose, or fat.

The information about building a protein is stored in DNA; each gene contains information to make one protein; when a new protein is needed, a copy of that gene is made, called messenger RNA (mRNA).The mRNA can leave the nucleus.

The information in the mRNA is translated into protein with the help of ribosomes.

removes the amino group from amino acids. If amino acids are not required, the amino groups are removed through deamination - ammonia is sent to the liver to be converted to urea and eventually excreted. After the removal of the nitrogen, the remnants of the amino acids can be converted to glucose, used as energy, or stored as fat.

enzymes break compounds apart (such as digestive enzymes).

enzymes build substances (for example, glycogen synthetase is used to stimulate the ability to store glucose as glycogen).

High-quality protein is digestible, and contains all the essential amino acids. Complete proteins provide all nine of the essential amino acids plus some of the nonessential ones; plant proteins are considered incomplete proteins, as one or more of the essential amino acids are always missing. Eggs, meat, soy, and dairy contain significant amounts of protein. A serving size of 3 ounces, which is about the size of a deck of cards, is plenty of protein for one meal.

Vegetarians must make sure to obtain adequate protein from soy, dried beans, legumes, and nuts. Vegetarian diets carry potential benefits, can be fiber-rich, and usually lead to a reduction in the risk for heart disease, high blood pressure, diabetes, cancer, stroke, and obesity.