Proteins Flashcards
Which of the following are considered the most important biological compound?
a. vitamins
b. carbohydrates
c. lipids
d. proteins
d. proteins
What are the basic structural units of proteins?
a. amino acids
b. monosaccharides
c. triglycerides
d. fatty acids
a. amino acids
Which of the following is a function of proteins?
a. catalysis
b. movement
c. storage
d. all of these
d. all of these
Which of the following is a structural protein?
a. cellulose
b. collagen
c. hemoglobin
d. insulin
b. collagen
Which of the following proteins is associated with the movement of muscles?
a. actin
b. ferritin
c. hemoglobin
d. insulin
a. actin
Which of the following proteins is associated with the storage of iron?
a. actin
b. ferritin
c. hemoglobin
d. insulin
b. ferritin
Which of the following proteins is a hormone?
a. casein
b. hemoglobin
c. insulin
d. all of these
c. insulin
- Identify a statement that is true of the functions of proteins.
a. Ferritin, a protein that is found in the liver, stores iron in the body.
b. Hemoglobin, a protein, carries oxygen from cells to the lungs.
c. Antigens are proteins that are produced by the body to counteract antibodies.
d. Keratin forms the skeletal muscles of the body.
a. Ferritin, a protein that is found in the liver, stores iron in the body.
Which of the following proteins can assist in blood clotting?
a. insulin
b. erythropoietin
c. fibrinogen
d. ferritin
c. fibrinogen
Which of the following statements is true of the water solubility of proteins?
a. Both fibrous and globular proteins are insoluble in water.
b. Both fibrous and globular proteins are soluble in water.
c. Fibrous proteins are insoluble in water.
d. Globular proteins are insoluble in water.
c. Fibrous proteins are insoluble in water.
Which of the following proteins stimulates the formation of red blood cells in the body?
a. fibrinogen
b. collagen
c. casein
d. erythropoietin
d. erythropoietin
Which of the following is not a fibrous protein?
a. actin
b. collagen
c. keratin
d. None, they are all fibrous proteins.
a. actin
Which of the following is an achiral amino acid?
a. proline
b. glycine
c. alanine
d. arginine
b. glycine
How many naturally occurring amino acids are commonly found in proteins?
a. 10
b. 20
c. 25
d. 100
b. 20
Which of the following amino acids contains nitrogen in its side chain?
a. cysteine
b. glycine
c. proline
d. leucine
c. proline
What is the most important aspect of an amino acid’s side chain?
a. its polarity
b. its shape
c. its size
d. none of these
a. its polarity
Which of the following amino acid side chains is hydrophobic?
a. acidic
b. basic
c. polar but neutral
d. none of these
d. none of these
Which of the following amino acid side chains is hydrophobic?
a. acidic
b. nonpolar
c. polar but neutral
d. none of these
b. nonpolar
Which of the following amino acid side chains is hydrophilic?
a. acidic
b. basic
c. polar but neutral
d. all of these
d. all of these
Which of the following amino acids is not optically active?
a. alanine
b. glycine
c. tryptophan
d. none, all of these are optically active
b. glycine
Which of the following statements is true of all amino acids?
a. All amino acids have a D-isomer.
b. All amino acids have an L-isomer.
c. The amino group is attached to the carbon atom of the carboxyl group.
d. The amino group and the carbon of the carboxyl group are attached to the same carbon atom.
d. The amino group and the carbon of the carboxyl group are attached to the same carbon atom.
Which of the following pair of amino acids has sulfur-containing side chains?
a. cysteine and glycine
b. cysteine and methionine
c. histidine and methionine
d. phenylalanine and tryptophan
b. cysteine and methionine
Which of the following is a β-hydroxy-α-amino acid?
a. asparagine
b. serine
c. tryptophan
d. none of these
b. serine
Which of the following amino acids has a hydroxyl side chain?
a. asparagine
b. glutamine
c. threonine
d. none of these
c. threonine
Which of the following pair of amino acids has nonpolar side chains?
a. cysteine and glycine
b. cysteine and methionine
c. histidine and methionine
d. phenylalanine and tryptophan
d. phenylalanine and tryptophan
Which of the following pair of amino acids has polar but neutral side chains?
a. cysteine and methionine
b. cysteine and serine
c. histidine and methionine
d. phenylalanine and tryptophan
Which of the following pair of amino acids has basic side chains?
a. cysteine and glycine
b. cysteine and methionine
c. histidine and lysine
d. phenylalanine and tryptophan
c. histidine and lysine
Which of the following statements is true of zwitterions?
a. They are positively charged.
b. They are negatively charged.
c. They are electrically neutral.
d. They are made up of basic amino acids.
Which of the following explains the unusually high melting points of amino acids?
a. their unusually high molecular weights
b. the polarity of their side chains
c. the presence of nitrogen atoms in their side chains
d. their existence as zwitterions in polar solvents
Which of the following is true of amino acids that are dissolved in water?
a. They exist in an un-ionized form at high pH.
b. They exist in an un-ionized form at low pH.
c. They exist in an un-ionized form only at a specific pH.
d. They do not exist in an un-ionized form at any pH.
d. They do not exist in an un-ionized form at any pH.
What is the approximate isoelectric point (pI) of most amino acids?
a. 3
b. 6
c. 7
d. 10
Which of the following amino acids has the lowest pI?
a. arginine
b. cysteine
c. glycine
d. glutamic acid
d. glutamic acid
Which of the following amino acids has the highest pI?
a. arginine
b. cysteine
c. glycine
d. glutamic acid
Which of the following statements is true of the isoelectric point of amino acids?
a. It is the same for all amino acids.
b. It is the pH at which an amino acid conducts electricity.
c. It is the pH at which an amino acid has equal numbers of positive and negative charges.
d. All of these statements are true.
Which of the following is true of an amino acid at a pH below its isoelectric point?
a. It will have a negative charge.
b. It will be electrically neutral.
c. It will have a positive charge.
d. It is impossible to predict the charge of an amino acid.
Which of the following is true of an amino acid at a pH above its isoelectric point?
a. It will have a negative charge.
b. It will be electrically neutral.
c. It will have a positive charge.
d. It is impossible to predict the charge of an amino acid.
a. It will have a negative charge.
What determines the functions of amino acids?
a. their molecular weight
b. their side chain
c. both molecular weight and side chain
d. neither molecular weight nor side chain
b. their side chain
Which of the following amino acids can be easily dimerized?
a. alanine
b. cysteine
c. glycine
d. methionine
Which of the following contains a disulfide bond?
a. alanine
b. cysteine
c. cystine
d. methionine
Which of the following diseases is associated with lower-than-normal levels of L-dopa?
a. Alzheimer’s disease
b. Schizophrenia
c. Parkinson’s disease
d. Bipolar disorder
Which of the following types of chemical reaction is involved in the conversion of dopamine to epinephrine?
a. addition
b. reduction
c. decarboxylation
d. methylation
What type of chemical reaction is involved in the formation of cystine from cysteine?
a. addition
b. reduction
c. oxidation
d. substitution
What type of chemical reaction is involved in the conversion of cystine to cysteine?
a. addition
b. reduction
c. oxidation
d. substitution
How many essential amino acids have acidic side chains?
a. 1
b. 2
c. 3
d. 4
How many essential amino acids have basic side chains?
a. 1
b. 2
c. 3
d. 4
c. 3
Which of the following amino acids has an imidazole group side chain?
a. lysine
b. tryptophan
c. histidine
d. tyrosine
Which amino acid can be found in proteins in both its protonated and unprotonated forms?
a. alanine
b. glycine
c. histidine
d. phenylalanine
c. histidine
Serotonin, a neurotransmitter, has a calming effect. Which of the following amino acids is the precursor of serotonin?
a. arginine
b. glutamic acid
c. isoleucine
d. tryptophan
Which of the following neurotransmitters is associated with manic-depressive schizophrenia?
a. adrenaline
b. norepinephrine
c. serotonin
d. none of these
c. serotonin
Which of the following amino acids has a guanidino group in its side chain?
a. asparagine
b. glutamic acid
c. arginine
d. none of these
c. arginine
Which of the following amino acids absorbs UV radiation at 280 nm?
a. phenylalanine
b. tryptophan
c. tyrosine
d. all of these
Which of the following amino acids absorbs UV radiation at 280 nm?
a. arginine
b. alanine
c. leucine
d. tyrosine
d. tyrosine
What is the chemical name of serotonin?
a. 5-hydroxyphenylalanine
b. 5-hydroxytryptamine
c. 3-hydroxytyrosine
d. 3-hydroxyvaline
b. 5-hydroxytryptamine
From which amino acid is tyrosine usually derived?
a. cysteine
b. phenylalanine
c. tryptophan
d. valine
Neurotransmitters known as catecholamines are formed from which amino acid?
a. cysteine
b. threonine
c. tyrosine
d. valine
c. tyrosine
Which pair of the amino acids is the precursors of norepinephrine and epinephrine?
a. aspartic acid and glutamic acid
b. cysteine and methionine
c. isoleucine and leucine
d. phenylalanine and tyrosine