Chapter 6 Nutrition 3314 - Baylor

Proteins have numerous important functions. For example, they are important for cell growth, repair, and maintenance. They also help maintain acid-base balance by acting as buffers.

Proteins help speed up chemical reactions. Proteins play an important role in immunity. Proteins help transport nutrients and other substances. Proteins help maintain fluid balance.

What would happen if Sarah consistently exceeded her daily protein requirement?

She could gain weight if the extra protein contributed to excess kilocalories over her energy needs.

Single amino acids, dipeptides, and tripeptides are absorbed here.

Small Intestines

Hydrochloric acid denatures protein here.

Stomach

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

TRue

How does your body use the protein once it has been ingested?

The liver uses amino acids to create glucose. If calorie intake is inadequate, amino acids can be used for production of energy. Amino acids are used to create new proteins

When variations, also called mutations, occur within genes, the proteins that are encoded by those genes are modified. Many times, mutations occurring in genes do not result in noticeable effects on the proteins synthesized from them, and are, therefore, harmless. Other times, however, a certain genetic mutation may affect the final structure and function of a protein enough to result in disease. Which of the following statements correctly applies to the genetic disorders sickle-cell anemia and phenylketonuria?

The mutation that causes sickle-cell results in production of hemoglobin proteins which are misshapen; some of them look like half-moons.

The body uses two types of amino acids: essential and nonessential. Which of the following statements about essential and nonessential amino acids is correct?

There are 11 nonessential amino acids.

Deamination occurs.

mostly in the liver

Essential Amino Acids

must be consumed in the diet

Nitrogen that has been removed during deamination __________.

is converted to urea and excreted through the urine Nitrogen that is removed from protein during deamination is converted to urea in the liver. The urea is transported to the kidneys, where it is excreted in the urine.

DNA does not build or synthesize a protein it encodes for; instead, DNA contains information that is copied by an enzyme to make _______, which leaves the nucleus and goes to the ribosome where the protein is built.

mRNA

it carries a copy of the DNA instructions that dictate the sequence of amino acids for making a specific protein

mRNA

the ribosome moves along this and reads the encoded information

mRNA

what compound carries the blueprint from DNA to the ribsomes during protein synthesis

mRNA

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

mRNA The enzyme polymerase copies the blueprint from DNA onto messenger RNA (mRNA). mRNA then travels out of the nucleus into the cytoplasm and attaches to the ribosomes. With the help of tRNA, the code is then translated into the sequence of amino acids needed to synthesize a new protein.

A serious protein-energy malnutrition disease is __________.

marasmus

How do we determine whether we are in protein balance?

measuring the amount of nitrogen consumed with the amount of nitrogen excreted We can assess a person's protein status by checking nitrogen balance, that is, by measuring the amount of nitrogen consumed and subtracting the amount of nitrogen excreted, mostly as urea.

To begin the translation stage, mRNA binds to a ribosome with the help of _______

rRNA

An example of mutual supplementation would be _______

red beans and rice

The _____ reads the mRNA strand, and with the help of tRNA, builds the corresponding amino acid chain.

ribosome

it reads the nucleotide sequence and helps build the corresponding sequence of amino acids

ribosome

it releases the amino acid chain once the chain is complete

ribosome

Which of the following foods would provide the highest quality protein in the smallest portion size? beans, corn, milk, chicken breast.

Chicken breast (Animal products are a source of highest quality protein, and protein is very concentrated. A 3-ounce serving of chicken will have approximately 25 grams of protein)

it transfers specific amino acids to the growing amino acid chain

tRNA

Ketosis is defined as __________.

the abnormal accumulation of ketones in the body as a result of excessive breakdown of fats caused by inadequate consumption of carbohydrates

____ contains all of the instructions for building the hundreds of thousands of proteins that are found in the human body.

DNA

________ occurs when a protein is exposed to heat, acid, bases, or mechanical agitation resulting in unfolding of the protein, though the peptide bonds remain intact.

Denaturation

______ describes an amino acid chain made up of two amino acids joined together.

Dipeptide

Which of the following statements about high-protein diets is correct?

Excess dietary protein may cause the development of kidney stones.

How much protein should Sarah add to her diet if she gets pregnant?

19g

Currently, __________ levels of protein structure have been identified.

4

An optimal intake of protein for Americans is approximately __________.

46 grams per day for women and 56 grams per day for men

What is the daily protein requirement for Sarah, a 136-lb, moderately active 32-year-old woman? Round the number of grams to the nearest whole number. During calculations, use numbers rounded to the first decimal place.

49 g

Added protein has been showing up in more and more packaged foods. Which of the following statements is correct about the added protein in packaged foods?

Certain segments of the population may need to supplement with more protein. In this case, packaged foods with added protein may make sense for those who have dietary challenges, such as allergies and food sensitivities, or picky eaters who won't eat eggs or meat.

instructions on how to build all proteins are stored in this molecule's nucleotide sequence

DNA

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

False

Once amino acids have entered the amino acid pool, their primary metabolic fate is to become part of a protein produced within individual cells. But this is not the only possible metabolic fate for amino acids. Which of the following could not be a metabolic fate for an amino acid after it becomes part of the amino acid pool?

It could be stored intact to be used for protein production another day.

Amino acids can be converted into glucose here

Liver

Amino acids that enter the bloodstream from the small intestine travel to here.

Liver

Food containing protein is crushed and moistened here

Mouth

The 20 different __________ are the building blocks used for protein synthesis.

amino acids

High-protein diets of predominately animal sources are associated with high __________.

blood cholesterol

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. A nonessential amino acid is created during protein metabolism by transferring the nitrogen group from an essential amino acid to a keto acid to form a new amino acid. A way to remember this process is to remember that the suffix "trans" means "to move"; transamination moves a part of one amino acid to a keto acid to make a new nonessential amino acid.

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

deamination Unlike excess fat or carbohydrates, excess amino acids cannot be stored for use as an energy source. The amino acids can be used for energy if the nitrogen group is first removed through deamination.

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

dipeptide (When two amino acids are joined together, the new molecule is called a dipeptide (di- means "two").

A pescovegetarian would include __________ in his or her diet.

fish

Symptoms such as edema, distention of the belly, loss of appetite, skin problems, and retarded growth and development are often associated with __________.

kwashiorkor

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

oligopeptide A string of four to nine amino acids is called an oligopeptide. When the string contains three amino acids, it is called a tripeptide, and if there are more than nine amino acids, the molecule is referred to as a polypeptide.

When amino acids join together, they form __________.

peptides

Which of the following vegetarian foods is almost identical in quality to meat?

soybean

Pepsin is formed from pepsinogen here.

stomach

Proteins are denatured by hydrochloric acid in the ______________.

stomach

A type of RNA that plays the important role of transferring specific amino acids to the growing amino acid chain in the ribosomes is called _____

tRNA

it collects and binds to individual amino acids that are needed for protein formation

tRNA

What is denaturation?

the uncoiling of the protein molecule by hydrochloric acid in the stomach When proteins reach the stomach, they are uncoiled by hydrochloric acid in a process called denaturation. The hydrochloric acid denatures, or uncoils, the strands of amino acids. This allows pepsin, a protein-digesting enzyme also released in the stomach, to hydrolyze proteins into shorter polypeptide chains and single amino acids.

Which of the following plant foods have the highest quality of protein? tofu, rice, whole-wheat bread, peanut butter

tofu (Tofu is made from soybeans, which is one of the plant foods that have high-quality protein. Its PDCAAS score is .78.)

An amino acid chain made up of three amino acids joined together is called a

tripeptide

This is a nutrient of concern in vegetarian diets.

vitamin D

Protein is digested in the small intestine by enzymes called __________________

proteases.

Proteases are produced here and delivered via a duct to the small intestine.

Pancreas

Nonessential Amino Acids (manufactured by the body)

Alanine Arginine Asparagine Aspartic Acid Cysteine Glutamic Acid Glutamine Glycine Proline Serine Tryosine

Approximately 50 percent of every protein molecule is composed of nitrogen.

False We know that 16 percent of every protein molecule is nitrogen and that the body retains this nitrogen as it becomes part of the protein chain.

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

False - Peptide Bond

How does protein in a peanut butter sandwich become amino acids that the body can use

Food containing protein is crushed and moistened with saliva. Proteins are denatured by hydrochloric acid, and pepsinogen is activated. Pepsin breaks down proteins into single amino acids and polypeptides. Proteases from the pancreas are secreted into the smallintestine. Proteases break down polypeptides into mostly tripeptides and dipeptides. Tripeptides and dipeptides are broken down into single amino acids.

__________ is a hormone that controls the release of pepsin and the production of hydrochloric acid.

Gastrin

A segment of DNA that encodes for the production of a specific protein is called a(n) ____

Gene

Essential Amino Acids (consumed in the diet)

Histidine Isoluecine Leucine Lysine Methionine Phenylalanine Threonine Tryptophan Valine

Proteins, along with carbohydrates and lipids, are one of the three macronutrients. Proteins are composed of amino acids, which are divided into two nutritional categories: essential and nonessential amino acids. Each amino acid molecule consists of a central carbon, an amine group, an acid group, a hydrogen atom, and a side chain. Choose the correct statement about essential, nonessential, and conditionally essential amino acids

Nonessential amino acids can be synthesized in the body, so they do not need to be consumed in the diet.

Steps of protein digestion

Normal protein, denatured protein, small peptide chains, amino acids

DNA contains all the genetic information necessary for production of every protein our bodies make. Read the statements below and select the correct statements regarding the role of DNA in protein synthesis.

Nuclear DNA cannot leave the nucleus. The DNA unwinds in order for a copy in the form of an mRNA molecule to be made of a gene

_____ is the active form of the digestive enzyme pepsinogen.

Pepsin

Part complete Which of the following statements is FALSE regarding nitrogen balance?

Pregnant women usually consume less nitrogen than they excrete. The goal is to achieve a neutral nitrogen balance. Most healthy adults who are weight stable are in nitrogen balance because they consume the same amount of nitrogen they excrete. Pregnant women, as well as children, bodybuilders, and people recovering from surgery or illness have an increased need for protein and are generally in positive nitrogen balance; that is, they ingest more nitrogen than they excrete. People who are injured or ill and those who are starving are usually in negative nitrogen balance; they excrete more nitrogen than they consume.

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. Specific carriers transport amino acids across the cell membrane into the intestinal cell. The process is known as active transport, and it requires energy. Protein chains are broken down into single amino acids or small peptide chains by proteases, secreted from the pancreas, inside the cell membrane. One of the many functions of protein is as a transport vehicle moving substances in and out of cell membranes.

Which of the following is true regarding the relationship between amino acids and protein?

Protein is made of essential and nonessential amino acids.

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

True

A vegetarian diet has many health benefits. However, some issues need to be considered before removing animal products from the diet to avoid deficiencies in essential amino acids and/or other nutrients. Choose the sentence below that correctly describes a vegetarian diet.

Vegetarians, especially vegans, need to consume adequate amounts of the essential amino acids by choosing complementary proteins and eating plant sources of complete protein like soy and quinoa.

Although high protein intake contributes to __________, this has not been associated with bone loss. calcium excretion muscle atrophy dementia hair loss

calcium excretion

Nonessential Amino Acids

can be made by the body

Essential and Nonessential Amino Acids

contain nitrogen used for protein production in the body can be broken down by the body to

Which of the following foods provides a moderate amount of protein per serving? shrimp, egg, oranges, corn

corn (Corn is a grain and is a moderate source of protein.)

Which of the following foods would have the lowest amount of protein per serving? Fruits, milk, beans or grains

fruits (Fruits generally have 1 gram or less of protein in one serving.)

This is the process by which cells use genes to make proteins.

gene expression

The stomach produces _________ , which denatures protein.

hydrochloric acid

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

hydrochloric acid and pepsin in the stomach saliva from the salivary glands in the mouth proteases secreted from the pancreas and the small intestine

Unlike lipids and carbohydrates, proteins are __________.

nitrogen containing

The structure in the cell that contains DNA is called the ____

nucleus.

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

peptide bond (A peptide bond is formed between two amino acids when the amine group from one amino acid binds to the acid group of the second amino acid forming the bond. This is an example of a condensation reaction, in which a molecule of water is produced.)

Phenylketonuria (PKU) is a disease in which the body cannot metabolize __________.

phenylalanine

Cleavage of proteins by pepsin in the stomach results in formation of shorter ________ , which get broken down further in the small intestine.

polypeptides

______________ contain 10 or more amino acids linked together.

polypeptides

Single amino acids that are absorbed in the small intestine travel to the liver via the ___________.

portal vein