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What element is found in proteins but not in carbohydrates and fats?

Nitrogen

In comparison to the composition of carbohydrates and fats, which element found in proteins makes them unique?

Nitrogen

Which of the following is the primary factor that differentiates one amino acid from another?

The side group

Which of the following elements is found in certain amino acids?

Sulfur

Terms used to classify amino acids in the diet include all of the following except

partially essential.

How many different kinds of amino acids make up proteins?

20

All of the following are contained in an amino acid except

an aldehyde group.

Approximately how many different amino acids are used in the synthesis of body proteins?

20

What is the simplest amino acid?

Glycine

Which of the following is not an essential amino acid in human nutrition?

Proline

Any of the following can be used by the body for the synthesis of a nonessential amino acid except

an essential mineral.

What amino acid is classified as conditionally essential when dietary intake of phenylalanine is insufficient or the body cannot normally metabolize phenylalanine?

Tyrosine

Which of the following is a feature of an essential amino acid?

It must be supplied by the diet

What type of reaction is required to bind two molecules of glycine together and release a molecule of water?

Condensation

When two amino acids are chemically joined together, the resulting structure is called a

dipeptide.

What is the composition of a tripeptide?

Three amino acids bonded together

What is meant by the amino acid sequence of a protein?

Order of amino acids in the peptide chain

A dispensable amino acid is one that

can be synthesized by the body.

In comparison to the well-defined structure of starch, which of the following is the most important factor that allows for the synthesis of thousands of different proteins?

Number of different amino acids

Which of the following would be classified as a polypeptide?

20 amino acids bonded together

The following amino acids are linked together: glycine-lysine-valine. This compound is a

tripeptide.

The weak electrical attractions within polypeptide chains account for the protein's

secondary structure.

Which of the following is a feature of hemoglobin?

It is constructed of 4 polypeptide chains

An example of a protein with quaternary polypeptide structures is

hemoglobin.

What is the process by which heat or acidity disrupts the normal shape of a protein chain?

Denaturation

The application of heat or acid to a protein that causes its shape to change is known as

denaturation.

What process results in the hardening of an egg when it is exposed to heat?

Denaturation

After a hamburger is eaten, in what organ is the hydrolysis of its proteins initiated?

Stomach

What is the name of the inactive form of the protein-splitting enzyme in the stomach?

pepsinogen

In what organ is pepsin active?

stomach

What digestive enzyme would be most affected in people who are unable to produce hydrochloric acid?

Pepsin

Protein-hydrolyzing enzymes are commonly known as

proteases.

The function of a protease is to

hydrolyze proteins.

What is the chief function of pepsin?

Cleaves proteins into smaller polypeptides

What percentage of dietary protein is hydrolyzed in the mouth?

0

Pepsinogen is also known as a(n)

zymogen.

After digestion of proteins, what products are absorbed into the circulation?

Free amino acids, and a few dipeptides and tripeptides

What is the usual fate of orally ingested enzyme supplements?

Digested by gastrointestinal proteases

What is an oligopeptide?

A string of about 4-9 amino acids

Which of the following statements is not characteristic of enzymes?

They are involved in synthesis reactions only

Which of the following describes the structure of pepsin?

Protein

All of the following are fates of amino acids in the intestinal tract except

some may be used for synthesis of gastric protease.

Of the following sources of amino acids, which would be best absorbed in normal, healthy people?

Whole proteins

Your cousin Wanda was born with a genetic defect affecting her digestion, namely, a lack of intestinal villus tripeptidases and dipeptidases. Which of the following digestive

Peptides → amino acids

Approximately how many different proteins are present in the human body?

30,000

Which of the following describes a process in protein synthesis?

The code to make a protein is carried by a strand of messenger RNA

Which of the following is a characteristic of protein synthesis?

Messenger RNA is constructed from a DNA template to carry instructions

The process whereby messenger RNA is made from a DNA template is

transcription.

What is a ribosome?

A structure upon which proteins are assembled

All of the following are features of protein in nutrition except

most of the body's thousands of proteins have been studied and characterized.

Your college dormitory roommate, James, told you that he's had anemia for quite some time and that it's from having abnormally-shaped hemoglobin. What type of anemia does James have?

Sickle-cell anemia

A common genetic variation which causes a change in the amino acid sequence in the structure of hemoglobin leads to the disease

sickle-cell anemia.

Which of the following is characteristic of sickle-cell anemia?

he abnormal structure of the hemoglobin alters the shape of the red blood cell

What is the structure of an enzyme?

Protein

What protein is intimately involved in the formation of scar tissue in wound healing?

Collagen

What type of protein would the body make in order to heal a wound?

Collagen

Which of the following is a characteristic of hormones?

Act as messenger molecules

Which of the following do(es) not function as a transport protein?

Collagen

What is the relationship between body proteins and water?

Proteins attract water

All of the following describe associations between protein nutrition and the body's water balance except

excessive protein losses by the kidney may lead to dehydration.

The conditions known as acidosis and alkalosis refer to a disruption of the body's

pH balance.

Tissue swelling that results from water accumulating between cells is known as

edema.

Proteins, because they attract hydrogen ions, can act as

buffers.

What function does a buffer perform?

Helps maintain a constant pH

Which of the following processes is regulated primarily by the buffering action of proteins?

pH balance

How do sodium and potassium travel into and out of cells?

There are transport proteins within the cell membrane that pick up and release the minerals across the membrane

What is opsin?

A light-sensitive protein

Which of the following proteins inactivates foreign bacteria and viruses?

Antibodies

The body's usual response to detection of antigens is to synthesize

antibodies.

Which of the following describes the structure of an antibody?

Huge protein molecule

Which of the following is involved in the clotting of blood?

Fibrin

How many grams of nitrogen are contained in a 2500-kcalorie diet that provides 15% of the energy as protein?

15

Which of the following may be used to determine protein utilization?

Nitrogen balance

When nitrogen taken into the body exceeds nitrogen losses, we say the person is in

positive nitrogen balance.

Which of the following defines protein turnover?

The sum of protein synthesis and degradation

What is the amino acid pool?

A mix of essential and nonessential amino acids derived from protein breakdown and dietary protein intake

Which of the following describes the state of nitrogen balance for a normal, healthy 35-year-old person who weighs 60 kg and consumes a diet that provides 75 g of protein and adequate energy?

Equilibrium

The body's amino acid pool consists of

both essential and nonessential amino acids.

What is the nitrogen balance of a person who consumed a 3500-kcalorie diet containing 10% protein and excreted a total of 12 grams of nitrogen?

+2 g

Which of the following would describe the state of nitrogen balance of a person who ingested 16 g of food nitrogen and lost 19 g of nitrogen?

Negative balance

What is the usual state of nitrogen balance for healthy infants, children, and pregnant women?

Positive

What amino acid is used to synthesize the neurotransmitter serotonin and the vitamin niacin?

Tryptophan

What is meant by protein turnover?

The synthesis and degradation of body proteins

What is the fate of excess dietary protein?

After absorption, the extra amino acids will be rapidly degraded

When amino acids are deaminated, the immediate products are ammonia and often a

keto acid.

Protein sparing in the body is best achieved when a person ingests

adequate levels of carbohydrate and fat.

A person who is starving is losing

glycogen, protein, and fat.

Which of the following illustrates a deamination reaction?

Removal of the amino group from an amino acid

Which of the following is the most likely side effect of a high-protein, low-carbohydrate diet?

Increased thirst

Which of the following compounds does not contain nitrogen?

Cholesterol

Which of the following is a consequence of excess protein intake?

Increased production and excretion of urea

Which of the following are precursors of urea synthesis?

All amino acids

What is the process whereby an amino group is combined with a keto acid to form an amino acid?

Transamination

In the metabolism of amino acids for energy, what is the fate of the amino group?

Excreted as urea

The body's need for water increases on a diet high in

Protein

What is the most likely reason for a person to have abnormally high blood ammonia levels?

Liver dysfunction

Jason is 35 years old and was recently diagnosed with 2 failing kidneys. He was advised to decrease the amount protein he consumes. If Jason cheats by eating an 8-ounce steak for dinner tonight, shortly thereafter there would most likely be an increase in the urea levels of his

blood.

What is the most likely reason for having an abnormally high blood urea level?

Kidney dysfunction

A prominent result of transamination reactions is the synthesis of

nonessential amino acids.

Your father, who has a high blood ammonia concentration, most likely has a poorly functioning

liver.

Your mother, who has a high blood urea content, most likely has a poorly functioning

kidney.

A reference protein equals or exceeds the essential amino acid requirements of all of the following population groups except

infants.

What is the percent digestibility of most plant proteins?

70-90

What is the percent digestibility of most animal proteins?

90-99

Which of the following food proteins has the best assortment of essential amino acids for the human body?

Egg

Which of the following is related to the quality of a food protein?

Essential amino acid balance

What primary factor governs the quality of a food protein?

Essential amino acid content

In the study of protein nutrition, what term describes the amount of amino acids absorbed from a given amount of protein consumed?

Digestibility

Which of the following is not considered to be a source of high-quality protein in human nutrition?

Corn

Which of the following animal-derived proteins is classified as a poor-quality protein?

Gelatin

What is a "limiting" amino acid in a protein?

An essential amino acid present in insufficient quantity for body protein synthesis to take place

If the diet is lacking an essential amino acid, what will be the course of action?

Protein synthesis will be limited

Which of the following could not be a limiting amino acid in the diet?

Glycine

Alberta is a 20 year old who has been a vegetarian for 3 years. She comes to you for advice after reading some material online by the Meat Promoters of America organization. One of their statements is: ". . . vegetarians are at risk for protein deficiency because they cannot consume all of the essential amino acids necessary for healthy individuals." How should Alberta be advised?

Although many foods don't provide all the essential amino acids individually, she could consume complementary proteins throughout the day, which would provide all the essential amino acids she needs

Which of the following is characteristic of protein nutrition in vegetarians?

Most vegetarians eating a variety of foods need not balance essential amino acid intake at each meal

What is the Daily Value for protein based on a 2000-kcalorie intake?

50 g

What is complementary protein nutrition?

A strategy that combines plant proteins in the same day to improve the balance of essential amino acids

In general, the protein quality in grains would be most improved by the addition of a plant protein rich in

lysine.

In general, the protein quality of legumes would be most improved by the addition of a plant protein rich in

methionine

Relative to animal proteins, which of the following amino acids is present in lesser amounts in proteins of legumes?

Tryptophan

Approximately what percentage of children worldwide have protein-energy malnutrition?

25

Acute protein-energy malnutrition in children is characterized by

low weight for height.

Chronic protein-energy malnutrition in children is characterized by

short height for age.

All of the following are characteristics of protein-energy malnutrition except

it almost always exhibits overt signs.

Marasmus occurs most commonly in children of ages

6-18 months.

You are reading a case study from a researcher at World University. The researcher has traveled to the largest city in India and is reporting on an illness present in a 15-month-old boy. The researcher described the child as extremely thin and bony, with wrinkled skin and enlarged fatty liver. For the past year, this child has subsisted almost entirely on diluted cereal drink. Your first thought is that all of these observations are characteristic of marasmus except for the

enlarged fatty liver.

Which of the following would you not expect to see in a person with kwashiorkor?

Increased physical activity

Which of the following is associated with the presence of tissue edema in kwashiorkor?

Low concentration of blood protein

Which of the following is not a characteristic of marasmus?

Affects brain development only minimally

Which of the following is a feature of malnutrition?

Dysentery is common and leads to diarrhea and nutrient depletion

At the end of your class presentation on "Protein-Energy Malnutrition," a student asks you to clarify how the rapid onset of protein-energy malnutrition occurs in kwashiorkor. How should you respond?

It is typically seen in patients who are 1-3 years old due to the sudden change in diet arising from their being weaned from breast milk after the birth of a sibling

What term describes the illness a child develops when the next child is born?

Kwashiorkor

Which of the following conditions is associated with edema?

Diminished concentration of blood proteins and hormones, which causes fluid to leak from the blood vessels

Kwashiorkor typically develops in children of ages

18-24 months.

n kwashiorkor, the loss of hair color is indirectly related to

inadequate intake of tyrosine.

In kwashiorkor, what mineral is often present in an unbound form that promotes bacterial growth?

Iron

What is the most likely explanation for the fatty liver that develops from protein deficiency?

Inability of the liver to synthesize lipoproteins for fat export

Which of the following is a feature of kwashiorkor?

It is typically precipitated in the undernourished child who has an infection

What is the usual initial therapy for the treatment of kwashiorkor?

Fluid balance restoration

Supplements of which of the following amino acids are reported to lower blood pressure and reduce homocysteine levels?

Arginine

Excessive amounts of homocysteine in the blood are thought to increase the risk for

heart disease.

All of the following are known to raise homocysteine levels except

excess arginine intake.

What type of diet is advised to rehabilitate a severely malnourished child?

Low protein

Which of the following is a feature of homocysteine?

It is increased in the blood of coffee drinkers

Which of the following describes a relationship between protein/amino acids and heart disease?

Elevated blood homocysteine levels are associated with smoking cigarettes and drinking alcohol

What ratio (mg:g) of calcium to protein intake is believed to promote optimal bone health?

20:1

Which of the following describes an association between protein intake and kidney function?

Restricting protein intake may slow the progression of kidney disease

In relation to the range of protein intake as a percentage of energy intake, what would be the highest safe level of protein intake for a 60-kg adult ingesting 2500 kcalories?

219 g

Which of the following describes a relationship between protein intake and calcium metabolism?

Calcium excretion rises with increasing intake of animal-derived proteins

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