Deck 6: Protein

Question 1

Serotonin is made from which amino acid?

A)tyrosine
B)niacin
C)threonine
D)tryptophan

Answer 1

D

Question 2

Three important enzymes remove ammonia from body cells.One is carbamoyl phosphate synthetase I.What are the other two?

A)branched-chain alpha-keto acid dehydrogenase and phenylalanine hydroxylase
B)alanine aminotransferase and aspartate aminotransferase
C)glutaminase and threonine dehydratase
D)glutamate dehydrogenase and glutamine synthetase

Answer 2

D

Question 3

Which regulatory peptides in the pancreatic phase of digestion activate the release of brush-border enzymes such as enteropeptidase?

A)trypsinogen and trypsin
B)cholecystokinin and secretin
C)carboxypeptidase A and B
D)elastin and chymotrypsin

Answer 3

B

Question 4

A function of hydrochloric acid in gastric juice during protein digestion is to ____.

A)neutralize the acidity of the stomach
B)inactivate pepsinogen by suppressing pepsin formation
C)denature the quaternary, tertiary, and secondary structures of protein
D)cleave peptide bonds

Question 5

If you were deficient in vitamins B₆ and B₁₂ and had high blood levels of homocysteine,what dietary substance could remove some of the homocysteine by donating a methyl group to form methionine?

A)biotin
B)betaine
C)serine
D)creatine

Question 6

Which amino acid is used to synthesize glutathione?

A)leucine
B)tryptophan
C)cysteine
D)valine

Question 7

When the diet is lacking in the amino acids lysine and threonine,____.

A)proteins will be made without one amino acid
B)the body will synthesize them
C)protein synthesis will be limited
D)another amino acid will be substituted so that synthesis is uninterrupted

Question 8

Which three amino acids cannot undergo transamination to an appreciable extent,making provision of their alpha-keto acids ineffective in lowering blood nitrogen concentrations in kidney disease patients?

A)leucine, isoleucine, valine
B)lysine, threonine, histidine
C)valine, tryptophan, phenylalanine
D)methionine, cysteine, phenylalanine

Question 9

The product(s)of pepsin's action is/are ____.

A)disaccharides
B)amylose
C)short-chain fatty acids
D)hydrolyzed proteins

Question 10

Which of the following amino acids is ketogenic?

A)glycine
B)alanine
C)leucine
D)aspartate

Question 11

Zwitterions are amino acids that have no net electrical charge because ____.

A)their side chains are not charged
B)they migrate to a neutral place in an electrical field
C)they are essential/indispensable
D)they have an amino group in their side chain

Question 12

Which organ serves as the primary site of amino acid metabolism?

A)kidney
B)muscles
C)liver
D)neuropeptides

Question 13

Name the genetic disease associated with the lack of the liver enzyme necessary to convert phenylalanine to tyrosine.

A)maple syrup urine disease
B)phenylketonuria
C)homocystinuria
D)lactase deficiency

Question 14

In general,most amino acids are absorbed from the ____.

A)stomach
B)duodenum and jejunum
C)ileum
D)colon

Question 15

Choose the correct order of enzyme activities in protein digestion.

A)tripeptidases, carboxypeptidases, pepsin, free amino acids
B)trypsin, pepsin, collagenase, dipeptidases
C)pepsin, trypsin, chymotrypsin, carboxypeptidase
D)trypsinogen, enteropeptidase, dipeptidase, chymotrypsin

Question 16

During protein digestion,peptides are broken into free amino acids mainly ____.

A)in the mouth
B)in the stomach
C)at the brush border
D)within the enterocyte

Question 17

What is the primary mechanism for regulation of amino acids in excess of need for synthesis of protein,providing about 50% of the liver energy needs after a meal?

A)oxidation
B)decarboxylation
C)phosphorylation
D)hydrogenation

Question 18

Using two high-energy bonds,arginosuccinate synthetase joins aspartate and citrulline to produce arginosuccinate in the cytosol.This is the rate-limiting step in ____ synthesis.

A)pyrimidine
B)purine
C)urea
D)creatine

Question 19

Urea synthesis occurs partly in the mitochondria and partly in the cytosol of the ____.

A)glomeruli
B)tubules
C)enterocytes
D)hepatocytes

Question 20

When the amino group has been removed from an amino acid,the carbon skeleton or α-keto acid may be used in many different ways.Which of the following is NOT a possible fate for the carbon skeleton?

A)conversion to glucose
B)oxidation for energy
C)production of ketone bodies
D)synthesis of creatine

Question 21

Legumes are limited in sulfur-containing amino acids,methionine and cysteine.What food group is considered complementary because it supplies these amino acids?

A)fruits
B)nuts
C)grains
D)starchy vegetables

Question 22

Which amino acid,when oxidized,spares the essential gluconeogenic precursors pyruvate and lactate?

A)cysteine
B)alanine
C)leucine
D)glutamine

Question 23

The branched-chain amino acids found in the systemic circulation include ____.

A)glycine, alanine, threonine
B)phenylalanine, tyrosine, tryptophan
C)valine, leucine, isoleucine
D)arginine, lysine, histidine

Question 24

Which protein does the FDA specify as a standard for comparison of protein quality?

A)casein
B)albumin
C)globulin
D)gluten

Question 25

Which of the following is a nitrogen-containing,nonprotein compound that performs an important function in the body?

A)glutathione
B)methionine
C)pepsin
D)actin

Question 26

A genetic defect diminishing branched-chain alpha-keto acid dehydrogenase (BCKAD)complex activity results in ____.

A)phenylketonuria
B)homocystinuria
C)cystathioninuria
D)maple syrup urine disease

Question 27

When evaluating protein quality,which of the following measures represents the gain in body weight on a test protein divided by the grams of protein consumed?

A)chemical score
B)BV (biological value)
C)PER (protein efficiency ratio)
D)NPU (net protein utilization)

Question 28

Which level of organization determines the final form of a protein molecule consisting of several polypeptide chains?

A)primary
B)secondary
C)tertiary
D)quaternary

Question 29

The amino acid reference pattern established for all people (except infants)is the amino acid requirements of ____.

A)high school students aged 15-18
B)middle school children aged 11-13
C)preschool children aged 1-3
D)adolescents aged 13-16

Question 30

The measure of how much nitrogen is retained in the body for maintenance and growth rather than absorbed is the ____.

A)protein efficiency ratio
B)biological value
C)net protein utilization
D)Tolerable Upper Intake Level

Question 31

What is the current Tolerable Upper Intake Level established for protein and amino acids?

A)ingestion of a diet supplying > 30% energy from protein
B)two times the RDA
C)42 mg/kg/day
D)no Tolerable Upper Intake Level has been established

Question 32

A particular amino acid is very important for several metabolic pathways in enterocytes and so it is often added to nutritional mixtures used for hospitalized patients.The important amino acid is ____.

A)tryptophan
B)glutamine
C)glycine
D)asparagine

Question 33

Amino acids that are metabolized mostly in skeletal muscles are those with side chains ____.

A)containing aromatic rings
B)that are branched
C)containing basic groups
D)containing sulfur atoms

Question 34

What two major systems are used for protein degradation in most cells?

A)mitochondrial and cytosolic
B)u-calpain and m-calpain
C)GTP-requiring and GTP-independent
D)lysosomal and ubiquitin-proteosomal

Question 35

What is one of the more common ways to evaluate protein quality in a food that does not involve nitrogen balance studies?

A)chemical score
B)net dietary protein calories percentage
C)biological value
D)net protein utilization

Question 36

Carbamoyl aspartate can only be used for ____ synthesis.

A)pyrimidine
B)purine
C)urea
D)creatine

Question 37

The measurement of food nitrogen consumed rather than retention of food nitrogen absorbed is called the ____.

A)protein efficiency ratio
B)biological value
C)chemical score
D)net protein utilization

Question 38

What percentage of resting energy expenditure is attributed to protein synthesis and degradation?

A)9%
B)10-25%
C)30-40%
D)45-55%

Question 39

The DIAAS assesses the digestibility of the amino acids in the ____.

A)ileum versus the colon
B)ileum versus the jejunum
C)ileum versus the duodenum
D)duodenum versus the colon

Question 40

Purine degradation results in the formation of xanthine and creation of _____ by xanthine oxidase.

A)polyamines
B)gout
C)citric acid
D)uric acid

Question 41

It has been suggested that adults over the age of 65 maintain a daily intake of protein in excess of ____.

A)1 g/kg of body weight
B)2 g/kg of body weight
C)3.5 g/kg of body weight
D)5.2 g/kg of body weight

Question 42

Which two substances promote amino acid degradation?

A)acetyl-CoA and dihydroxy acetone phosphate
B)insulin and glucagon
C)glucocorticoids and glucagon
D)acetoacetate and acetaldehyde

Question 43

The production of glucose from a noncarbohydrate source is ____.

A)glycogenolysis
B)glycolysis
C)glycogenesis
D)gluconeogenesis

Question 44

Under fasting conditions,one would expect to find large amounts of free ammonia in the bloodstream due to the breakdown of amino acids for energy.

Question 45

It is estimated that the intestine uses 30-40% of some of the essential amino acids absorbed from the diet.

Question 46

Assessment of nitrogen intake is based on ____.

A)amino acid intake
B)protein intake
C)carbohydrate intake
D)lipid intake

Question 47

When BCAAs are catabolized to their corresponding keto acid in muscle,the nitrogen must be transported directly to the kidney as glutamine.

Question 48

The indispensable amino acid with the lowest Recommended Dietary Allowance is ____

A)leucine
B)valine
C)histidine
D)tryptophan

Question 49

In addition to protein synthesis,the brain uses amino acids for the synthesis of other N-containing compounds such as neurotransmitters.

Question 50

Succinyl-CoA is generated by the oxidation of ____.

A)leucine
B)isoleucine
C)methionine
D)valine

Question 51

Bile is needed to produce taurocholate and glycocholate.

Question 52

Urea synthesis only occurs in the liver and kidneys.

Question 53

The liver is the site for transamination of all amino acids.

Question 54

For a transport protein that spans a cell membrane,one would expect to find hydrophobic amino acids clustered together within the membrane.

Question 55

Which enzyme's activity is dependent on vitamin B₆?

A)phenylalanine hydroxylase
B)tyrosine aminotransferase
C)tyrosine hydroxylase
D)tryptophan dioxygenase

Question 56

An intracellular deficiency of protease will interfere with ____.

A)protein degradation
B)alcohol metabolism
C)autophagy
D)glycogenolysis

Question 57

The Estimated Average Requirement for protein for adults (men and women aged 19 years and older)is ____

A)5 g of protein per kg of body weight
B)2 g of tyrosine protein per kg of body weight
C)0.66 g of protein per kg of body weight
D)0.5 g of protein per kg of body weight

Question 58

Which process is NOT a source of ammonia ions in the body?

A)creation of urea by the liver
B)generation by deamination of amide groups from glutamine
C)ingestion and absorption from foods
D)generation by bacterial lysis of urea and amino acids in the GI tract

Question 59

A variety of transporters exist on cell membranes to handle all of the different types of amino acids.

Question 60

Dietary proteins must be completely hydrolyzed to free amino acids,because only free amino acids are absorbed by the enterocyte.

Question 61

Several companies are now enriching enteral and parenteral nutrition products with glutamine.What is the rationale for this procedure?

Question 62

Match the amino acid to its precursor(s).
a.glutamate,ammonia
b.glutamate
c.phenylalanine
d.methionine,serine
e.glutamine or glutamate,aspartate
cysteine

Question 63

Match the category of physiological proteins with their function.
a.chemical messengers secreted by endocrine tissue and transported to target organs where they regulate metabolic processes
b.combine with nutrients and regulate their circulation and their flow into and out of cells
c.bind to antigens and inactivate them or cause them to be destroyed
d.catalysts that change the rate of reactions occurring in the body
e.fibrous and contractile proteins found in bone,teeth,skin,muscles,blood vessels,and hair
transport proteins

Question 64

Match the amino acid to its precursor(s).
a.glutamate,ammonia
b.glutamate
c.phenylalanine
d.methionine,serine
e.glutamine or glutamate,aspartate
arginine

Question 65

In both sexes,serum testosterone levels rise during adolescence.

Question 66

Transamination and Deamination: What are these two reactions in amino acid metabolism (draw a diagram if that is helpful)? Why are they important? (Hint-transamination is important for two reasons; deamination,essentially one.)How do different tissues factor into these reactions?

Question 67

Match the amino acid to its precursor(s).
a.glutamate,ammonia
b.glutamate
c.phenylalanine
d.methionine,serine
e.glutamine or glutamate,aspartate
glutamine

Question 68

Match the amino acid to its precursor(s).
a.glutamate,ammonia
b.glutamate
c.phenylalanine
d.methionine,serine
e.glutamine or glutamate,aspartate
tyrosine

Question 69

Lysosomes are found in all mammalian cells.

Question 70

A mutation in the genetic code (i.e.,DNA)could result in the wrong amino acid inserted into the synthesis of a given protein,thereby affecting the ability of the protein to function properly due to changes in its conformation.

Question 71

Match the category of physiological proteins with their function.
a.chemical messengers secreted by endocrine tissue and transported to target organs where they regulate metabolic processes
b.combine with nutrients and regulate their circulation and their flow into and out of cells
c.bind to antigens and inactivate them or cause them to be destroyed
d.catalysts that change the rate of reactions occurring in the body
e.fibrous and contractile proteins found in bone,teeth,skin,muscles,blood vessels,and hair
hormones

Question 72

Match the category of physiological proteins with their function.
a.chemical messengers secreted by endocrine tissue and transported to target organs where they regulate metabolic processes
b.combine with nutrients and regulate their circulation and their flow into and out of cells
c.bind to antigens and inactivate them or cause them to be destroyed
d.catalysts that change the rate of reactions occurring in the body
e.fibrous and contractile proteins found in bone,teeth,skin,muscles,blood vessels,and hair
structural proteins

Question 73

Incomplete proteins are derived from foods of animal origin such as eggs,milk,cheese,meat,and fish.

Question 74

What is the role of the liver in amino acid metabolism? Discuss three actions that occur in the liver as amino acids from the portal vein enter the liver.Your answer should include the types of compounds that are synthesized and the metabolic reactions involved.

Question 75

Total body water increases steadily from birth to 12 months of age,after which it begins to decrease at a similar rate in all adults.

Question 76

During fasting conditions,the circulating levels of glutamine and alanine are elevated-why is this? Hint: this question is focused primarily on the muscle,but also includes other tissues.

Question 77

Match the category of physiological proteins with their function.
a.chemical messengers secreted by endocrine tissue and transported to target organs where they regulate metabolic processes
b.combine with nutrients and regulate their circulation and their flow into and out of cells
c.bind to antigens and inactivate them or cause them to be destroyed
d.catalysts that change the rate of reactions occurring in the body
e.fibrous and contractile proteins found in bone,teeth,skin,muscles,blood vessels,and hair
enzymes

Question 78

Match the amino acid to its precursor(s).
a.glutamate,ammonia
b.glutamate
c.phenylalanine
d.methionine,serine
e.glutamine or glutamate,aspartate
proline

Question 79

Match the category of physiological proteins with their function.
a.chemical messengers secreted by endocrine tissue and transported to target organs where they regulate metabolic processes
b.combine with nutrients and regulate their circulation and their flow into and out of cells
c.bind to antigens and inactivate them or cause them to be destroyed
d.catalysts that change the rate of reactions occurring in the body
e.fibrous and contractile proteins found in bone,teeth,skin,muscles,blood vessels,and hair
immunoproteins

Question 80

What is meant by protein turnover? What general types of protein compounds are made in cells via protein synthesis? How do amino acid catabolism and dietary amino acids factor into protein turnover?