NUT Chapter 6

nonessential

11 are nonessential and can be synthesized in the body.

Dipeptide

2 amino acids joined by a peptide bond

Tripeptide

3 amino acids joined by a peptide bond

If used for energy, protein provides

4 kcal/g.

Which of the following foods would have the lowest amount of protein per serving?

fruits

Amino acid pools in the body contain amino acids from all of the following sources except

gluconeogenesis

Nitrogen that has been removed during deamination __________.

is converted to urea and excreted through the urine

Polypeptide

more than 10 amino acids joined by a peptide bond

Essential amino acids

must be provided by the diet.

Proteins differ from carbohydrates and lipids in that they contain ___________.

nitrogen

The body can synthesize __________ from amino acids.

nonessential proteins

The primary structure of a protein refers to its

order of amino acids.

Proteins

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.

Deamination

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.

Which component of an amino acid confers its unique qualities?

side chain

The function of the hormone gastrin is to

stimulate the release of HCl.

A complete protein is a protein that

supplies all the essential amino acids.

Genes are DNA codes for

synthesizing more than 100,000 specific proteins.

Tertiary structure

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

The fate of most digested dietary protein is __________.

circulation in the blood as amino acids

Which of the following is true regarding enzymes?

They are biological catalysts that speed up reactions.

The side chain of an amino acid differentiates one amino acid from another.

True

Quaternary structure

Two or more polypeptide chains cluster.

What Is a Vegetarian Diet

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.

Peptide

amino acid chain made of less than 50 amino acids

The building blocks of proteins are

amino acids.

A molecule with four to nine amino acids joined together by peptide bonds is referred to as __________.

an oligopeptide

Secondary structure

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

amino acids

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.

Which of the following foods provides a moderate amount of protein per serving?

corn

To use amino acids for energy, the nitrogen must first be removed from the amino acid. This process is called __________.

deamination

A chain of two amino acids is referred to as a __________.

dipeptide

Catabolic

enzymes break compounds apart (such as digestive enzymes).

Anabolic

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

What secretions are needed to digest complex proteins into single amino acids for absorption?

All of the listed responses are correct.

Amino acids are bound together by a chemical bond known as an amino acid bond to form proteins.

False

Chemical digestion of protein begins in the mouth with enzymes found in the saliva.

False

Deamination occurs mostly in the brain.

False

The digestion of polypeptides begins in the mouth with the enzyme pepsin.

False

In the stomach, protein is denatured by

HCl.

Best Food Sources of Protein

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.

Essential

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

Digesting and Absorbing Protein

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.

Which of the following statements regarding protein absorption is true?

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

Which of the following is true about the quality of protein?

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

conditionally essential

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.

Transcription

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.

Translation

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

Primary structure

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

The bond that is formed when two amino acids join together is called __________.

a peptide bond

Excess protein consumed is converted to __________.

body fat

A nonessential amino acid is made __________.

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

Which of the following foods would provide the highest quality protein in the smallest portion size?

chicken breast

Amino acids found in the amino acid pool __________.

can be used for protein synthesis

Protein

chain of more than 50 amino acids

denature

changes their shape (untangles them)

During the process of denaturation, a protein changes

its shape and function.

A type of malnutrition characterized by a severe deficiency of dietary protein but sufficient kilocalories is referred to as

kwashiorkor.

Which of the following amino acids are considered essential?

lysine, methionine, and threonine

What compound carries the blueprint from DNA to the ribosomes during protein synthesis?

mRNA

What is denaturation?

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

Which of the following plant foods have the highest quality of protein?

tofu