Bio155 Mastering Nutrition Chapter 6

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.

Proteins called __________ aid the immune system in its fight against bacteria, viruses, and other foreign substance by binding to them and helping to inactivate or destroy them.

antibodies

Proteins help control the acid-base balance in the body by acting as ________.

buffers

_________ 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

The quality of a protein is determined by the __________.

digestibility of the protein and amounts of essential amino acids

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

dipeptide

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

dipeptide

__________ is the active form of a digestive enzyme in the stomach that breaks polypeptide chains into smaller polypeptides.

pepsin

The chemical bonds that connect amino acids are called __________.

peptide bonds

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

polypeptide strands

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

portal vein

Healthy growing children and adolescents are in __________.

positive nitrogen balance

Which is not a good snack choice?

potato chips

The continual process of degrading and synthesizing protein is called _________.

protein turnover

Inadequate intake of protein and/or calories is known as ___________.

protein-energy malnutrition

Legumes are in which two USDA MyPlate groups?

proteins and vegetables

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

ribosome

A medical condition caused by a change in the amino acid sequence of hemoglobin is called __________.

sickle cell anemia

Which vegetarian protein is an example of a complete protein?

soy

Proteins are digested by enzymes found in the __________.

stomach and small intestine

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

To estimate whether a person's protein intake is adequate to meet his or her protein needs, researchers __________.

use a nitrogen-balance procedure

When the amine group is removed, the carbon-containing component of amino acids can be __________.

used for energy

A peanut butter-and-jelly sandwich is a better snack if it is made with __________.

whole-grain bread

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

an oligopeptide

How does your body use the protein once it has been ingested? Consider the following statements and select the correct ones regarding protein use.

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

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

- An mRNA molecule is a copy of a gene on the DNA molecule. - Nuclear DNA cannot leave the nucleus.

People choose to follow a vegetarian diet for a variety of reasons ranging from religious views and animal rights concerns to apprehension over the environment. No matter the reason, being vegetarian comes with certain benefits and risks that must be balanced to achieve a healthful diet. Please choose the correct statements about vegetarian diets.

- Complementary proteins do not need to be consumed in the same meal. - Vegans must obtain vitamin B12 from supplements or fortified foods. - A lacto-ovo-vegetarian consumes eggs and dairy products.

How does protein in a peanut butter sandwich become protein that your body can use? Think about the digestive and absorptive process beginning with the first bite of that sandwich, until the amino acids enter the circulatory system. Focus your attention on the steps involved in protein digestion illustrated in the focus figure. Rank in the correct order from the first bite to the amino acids entering the circulatory system.

1. Mechanical digestion in the mouth breaks down the food. 2. A bolus enters the stomach 3. Hydrochloric acid denatures proteins and activates pepsinogen to form pepsin 4. Pepsin breaks down proteins into polypeptide strands 5. Chyme travels from the stomach to the small intestine 6. Enzymes from the pancreas are secreted into the small intestine 7. Enzymes in the small intestine break down polypeptide strands into mostly tripeptides and dipeptides 8. Tripeptides and dipeptides are broken down into single amino acids that enter the blood and travel to the liver

In order for protein from food to be absorbed and used, it from food must be digested into smaller components. Consider what happens when you eat a high-protein food like scrambled eggs, and rank the steps in the correct order. Rank the steps of protein digestion in order, starting with the step that occurs first.

1. Mechanical digestion results in the formation of a bolus 2. Stomach acid denatures proteins 3. Pepsin breaks the polypeptide chains into shorter chains 4. Pancreatic enzymes cleave peptide bonds, leaving dipeptides, tripeptides, and single amino acids 5. Enzymes from the small intestine lining act on protein remnants, breaking them into single amino acids, which are absorbed into the cells of the lining 6. Single amino acids travel through the bloodstream to the portal vein and then to the liver

Protein should make up between __________ of the day's total energy intake.

10% to 35%

There are _____ unique amino acids in the human body.

20

An optimal intake of protein for Americans is approximately __________.

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

The recommended daily protein intake for a healthy adult weighing 165 pounds is _____ grams.

60

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

All of the listed responses are correct. - hydrochloric acid and pepsin in the stomach - saliva from the salivary glands in the mouth - proteases secreted from the pancreas and the small intestine

Protein synthesis is directed by __________ in the nucleus of the cell.

DNA

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

DNA

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

Excess dietary protein may cause the development of kidney stones.

____________ is a severe deficiency of dietary protein, resulting in swelling in the feet, legs, and stomach among other symptoms.

Kwashiorkor

In this activity, you will sort each phrase regarding protein digestion and absorption according to the organ in which the function takes place.

Mouth: mechanical digestion begins here Stomach: HCI denatures protein here, HCI is secreted here, pepsin is formed from pepsinogen here Small intestine: single amino acids, dipeptides, and tripeptides are absorbed here Pancreas: enzymes that digest amino acid chains are produces here and delivered via a duct to the small intestine Liver: amino acids that enter the bloodstream from the small intestine travel to here

__________ are stockpiles found in the blood and other cells of the body that can be used to build new proteins.

amino acid pools

Which of the following statements is FALSE regarding nitrogen balance?

Pregnant women usually consume less nitrogen than they excrete.

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.

Drag the labels into the correct bin to identify the role(s) each of the following components plays in protein synthesis. Drag the appropriate items into their respective bins.

Ribosome - it reads the nucleotide sequence and helps build the corresponding sequence of amino acids - it releases the amino acid chain once the chain is complete mRNA - it carries a copy of the DNA instructions that dictate the sequence of amino acids for making a specific protein - the ribosome moves along this and reads the encoded information tRNA - it transfers specific amino acids to the growing amino acid chain DNA - instructions on how to build all proteins are stored in this molecule, housed in the nucleus of the cell

What is a benefit of consuming soy foods?

Soy foods provide high-quality protein.

Which of the following would be good sources of iron for Megan?

Special K and enriched bread

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

amino acids

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 considered harmless. Other times, a 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 or phenylketonuria?

The mutation that causes sickle-cell anemia results in production of hemoglobin proteins which crystallize causing misshapen red blood cells; 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.

Why are snacks important?

They provide energy and fight fatigue throughout the day.

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

a peptide bond

An example of a healthy, protein-laden vegetarian lunch is __________.

a salad with beans and tofu, and a bowl of bean soup

To make your salad more appealing yet still healthy, try to use __________.

a variety of vegetables

The ________ is also known as the carboxyl group.

acid group

The part of an amino acid that contains nitrogen is called the _______.

amine group

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.

Amino acids found in the amino acid pool __________.

can be used for protein synthesis

What is the most frequently consumed source of saturated fat in Americans' diets?

cheese

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

chicken breast

Most enzymes are proteins, but some may utilize ________ in the form of vitamins to help with reactions.

coenzymes

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

corn

Which of the following is not a good protein source?

cucumbers

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

deamination

In addition to containing the "Dynamic Foursome," good snack choices have the added benefit of being __________.

easy to pack

What would be the best way for Taylor to establish the correct nitrogen balance?

eat more beans or fish

Amino acids that the human body is unable to synthesize are called __________.

essential amino acids

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

false

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

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

The "Dynamic Foursome" is carbohydrates, protein, fiber, and _____.

fat

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

fruits

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

gene

Which of the following actions or activities will not cause a protein's structure to break down?

gently stirring

You do not need to eat meat to get enough protein in your diet, provided that you __________.

get enough protein from a variety of plant sources

Consistently eating too many high-protein foods can lead to a higher risk for __________.

heart disease due to higher levels of fats, kidney problems, and calcium loss from bones

___________ direct activity in the body and can be made of proteins or lipids.

hormones

A protein that acts as a hormone is _____.

insulin

Nitrogen that has been removed during deamination __________.

is converted to urea and excreted through the urine

Protein consumed in excess of body needs __________.

is stored as body fat

A high-protein diet can increase the risk of __________.

kidney stones

The primary organ responsible for excreting nitrogen-containing waste as urea is the _____.

kidneys

After meeting with the dietitian, Megan wants to eat dairy products, but not eggs. What kind of vegetarian diet will she follow?

lacto-vegetarian

The organ responsible for conversion of amino acids into proteins or into glucose when they enter the bloodstream is the __________.

liver

Which of the following amino acids are considered essential?

lysine, methionine, and threonine

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

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

mRNA

How do we determine whether we are in protein balance?

measuring the amount of nitrogen consumed with the amount of nitrogen excreted

Which of the following foods are not eaten by a pescatarian?

meat and poultry

Protein bars, compared with a peanut butter sandwich, are most likely to be __________.

more expensive plus higher in saturated fat and sugar

All amino acids contain carbon, hydrogen, oxygen, and _____.

nitrogen

The structure in the cell that contains DNA is called the ________.

nucleus

A vegetarian diet may be low in __________.

omega-3 fatty acids and vitamins B12 and D

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

What is denaturation?

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

An important function of protein that is lacking in the condition known as kwashiorkor is __________.

to provide fluid balance in the body

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

tofu

__________ carry many substances through the blood or allow movement of substances in and out of cells.

transport proteins

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

tripeptide

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

true