Biochem test 2
Which statement concerning the biomolecules DNA is incorrect?
DNA stands for diribonucleic acid.
What is the process of altering the shape of a protein without breaking the amide bonds that form the primary structure?
Desaturation
What is the strongest type of interaction between two cysteine amino acid side chains in a protein?
Disulfide bond
Which conditions are commonly diagnosed by measuring the levels of specific enzymes in the blood?
Heart attack
Which is an example of a globular protein?
Hemoglobin
Which statement concerning the replication of DNA is not true?
Replication occurs in only one direction on the template strand, from the 5' end to the 3' end.
What is the particular sequence of amino acids of a protein that are joined together by peptide bonds called?
The primary structure of a protein
What is the structure of the dipeptide Ser-Gly?
The second one
Which is not a stop codon?
UGC
Which sequence is not possible?
UTAGA
Which base is found in DNA or RNA, but not both?
Uracil
Which type of mutation occurs when a DNA sequence changes from GGA TCA CCG GAA.... to GGA TCC CGG....?
a deleted mutation
Which is a genetic disease?
all diseases
Each individual tRNA contains ________.
an anticodon of three nucleotides that is complementary to the codon in mRNA and identifies individual amino acids
. DNA consists of two polynucleotide strands that wind into a left-handed double helix.
false
A chromosome is a segment of a DNA molecule that codes for a specific protein.
false
A dipeptide contains two amino acids joined together by two amide bonds.
false
A triplet codon is a sequence of three amino acids in a protein that signals for transcription
false
All amino acids have at least one chirality center
false
Amino acids typically exist in nature as neutral molecules with all uncharged atoms
false
Hemoglobin, collagen, and myoglobin are all examples of conjugated proteins.
false
Humans can synthesize only twenty of the amino acids needed for proteins.
false
In hydrolysis of a peptide or protein, the addition of water breaks the hydrogen bonds that hold the amino acids together in the peptide chain
false
In the process of translation, the genetic code contained in DNA is rewritten in mRNA, which leaves the nucleus and carries the information to the ribosomes for protein synthesis.
false
In the transcription "cartoon" shown, the direction of transcription is from right to left.
false
Insulin is a small protein consisting of two polypeptide chains held together by hydrogen bonds.
false
Nucleosides are formed by adding a phosphate group to the 5'-OH of a nucleotide
false
The "cartoon" shown is an example of competitive inhibition.
false
The Fischer projection below represents a basic amino acid
false
The lock-and-key model is often used to explain why some enzymes catalyze a wide variety of substrate reactions.
false
The peptide leucyl phenylalanylvalylvaline is abbreviated as Leu-Phen-Ala-Val-Val.
false
The strand of DNA used for RNA synthesis is called the information strand
false
The amino acids aspartic acid and glutamic acid have a +1 net charge at low pH, and a -2 net charge at high pH.
true
The enzyme in the ribbon diagram shown is composed primarily of β-pleated sheets.
true
The hydrolysis of the amide bonds in a protein forms the individual amino acids that comprise the primary structure.
true
The nucleic acid DNA stores the genetic information of a particular organism, while the nucleic acid RNA translates this genetic information into the synthesis of proteins needed by cells for proper function and development.
true
The primary structure of a polynucleotide is the sequence of nucleotides that it contains, which is determined by the identity of the bases.
true
The restriction enzyme BamHI recognizes the DNA sequence GGATCC and cuts the DNA between the two G's. Given the segment of double-stranded DNA shown below
true
The β-pleated sheet arrangement of a protein is favored by amino acids with small side chains.
true
The β-pleated sheet forms when two or more peptide chains, called strands, line up side-by-side with the C=O and N-H bonds in the plane of the sheets.
true
When inserted into a bacterium, recombinant DNA can be used to prepare large quantities of useful proteins.
true
Serine exists primarily in its neutral form at a pH ~ 6.
true
The "cartoon" shown is an example of noncompetitive inhibition.
true
The amide bonds in peptides and proteins are called peptide bonds.
true
How many different dipeptides can be formed when one valine reacts with one glycine?
2
There are ________ amino acids that occur naturally in proteins.
20
Proteins are long chains of amino acids joined together by peptide bonds. Which structure properly depicts the peptide bond formed between two generic amino acids?
2nd one
How many chirality centers are in leu-enkephalin (structure shown)?
3
How many hydrogen bonds form between a G-C base pair in a DNA double helix?
3
What is the complementary strand for the DNA strand 5'-AAGGTAGC-3'?
3'-TTCCATCG-5'
What is the structure of the amino acid phenylalanine at pH 1?
3rd one
The term protein is usually reserved for polymers of more than ________ amino acids.
40
Which mRNA sequence codes for the amino acid sequence Leu-Gly-Asp-Arg?
5' UUA GGA GAU AGA 3'
Which statement is not true?
A cofactor is always a metal ion needed for an enzyme-catalyzed reaction to occur.
What is a nucleoside?
A monosaccharide + a base
What type of inhibitor binds to the enzyme but does not bind at the active site?
A noncompetitive inhibitor
The combination of a monosaccharide like ribose or deoxyribose, a base like purine or pyrimidine, and a phosphate unit is called ________.
A nucleotide
Which is not one of the elements needed to amplify DNA by polymerase chain reaction (PCR)?
A restriction endonuclease enzyme that cleaves DNA at specific locations
An informational DNA sequence segment is initially AAA ATG TGA CCC. Which mutation would have the most significant effect on the resultant protein synthesized?
AAA ATT TGA CCC
A DNA sequence segment is initially AAA ATG TGA CCC. Which mutation would have the least effect on the resultant protein synthesized?
AAG ATG TGA CCC
What polypeptide would be synthesized from the following template strand of DNA: 3' CGG AGA CGG ACG 5'?
Ala-Ser-Ala-Cys
Which component is not part of a nucleotide?
An amino acid
Which amino acid is a basic amino acid?
Arginine
What is the three-letter abbreviation of asparagine?
Asn
Hydrogen bonding plays an important role in all but one of the items below. Which one does not involve hydrogen bonding?
DNA primary structure
How are the correct amino acids brought to the ribosomes for protein synthesis?
By tRNA molecules that contain the complementary sequence of an mRNA codon in their anticodon loop
What is the abbreviation of the polynucleotide shown?
CAT
What is the function of myosin in the human body?
Control muscle contraction
Which choice is the only amino acid capable of forming a disulfide bond?
Cysteine
D-Amino acids have the -NH3+ group on the left side in the Fischer projection.
False
The Fischer projection below represents a naturally occurring amino acid
False
The reactant in an enzyme-catalyzed reaction is called a cofactor
False
What is the N-terminal amino acid in the tetrapeptide glycylalanyisoleucylmethionine?
Glycine
Which is the simplest amino acid?
Glycine
DNA is a double-stranded nucleic acid that exists as a double helix. Which is responsible for holding the double helix of DNA together?
Hydrogen bonding between complementary bases on each strand
What is a zymogen?
INactive precursor of an enzyme
About one half of the 223 amino acid residues in the enzyme trypsin are hydrophobic. Where in the tertiary structure of this globular protein are these residues most likely to be found?
In the interior of the folded protein.
A reversible inhibitor does which of the following?
It binds to an enzyme but then enzyme activity is restored when the inhibitor is released
DNA isolated from human cheek cells was found to contain 21% guanine. Which statement concerning the base composition of this DNA sample is true?
It contains 21% cytosine, 29% adenine, and 29% thymine.
What is the name of the amino acid shown below?
L-cysteine
What is the strongest type of interaction between the side chains of an isoleucine amino acid and a phenylalanine amino acid in a protein?
London Dispersion force
Which of the following is not of the causes of protein denaturation?
Low temperature
Which amino acid sequence is coded for by the mRNA sequence 5' AAG GCU AGU GGC 3'?
Lys-Ala-Ser-Gly
What is the C-terminal amino acid in the tetrapeptide glycylalanyisoleucylmethionine?
Methionine
Which is not one of the three stages in translation?
Mutation
Which protein stores O2 in tissues?
Myoglobin
Which is an example of a cofactor?
NAD+
A polynucleotide contains ________.
One free phosphate group at the 5' end
What is the charge on an amino acid at a pH below its pI?
Positive
Which amino acid sequence is coded for by the mRNA sequence 5' CCA AAC UGG GUA 3'?
Pro-Asn-Trp-Val
What is the one-letter abbreviation of arginine?
R
What is the process by which DNA makes a copy of itself when a cell divides?
REPLICATION
Which choice is a polynucleotide that is a polymer of ribonucleotides?
RNA
Denaturation of a protein results in the loss of its native conformation and its biological activity. Which statement best describes what happens to a protein when it is denatured?
Secondary, tertiary, and quaternary levels of structure are disrupted.
Which Fischer projections represent naturally-occurring amino acids?
Structure 2 and 3
Consider the following forms of the amino acid valine (Val). Which statement concerning these structures is false?
Structure I represents the form of Val presents in blood at physiological pH.
Consider the following forms of amino acid serine (Ser). Which statement concerning these structures is true?
Structure IV represents the form of Ser present at its isoelectric pH.
Which sequence has a purine base at the 3' end?
TCTAG
How is a dipeptide formed?
The -NH3+ group of one amino acid forms an amide bond with the carboxylate (-COO-) of another amino acid, and the elements of H2O are removed.
Which is not a characteristic of an α-helix?
The R groups of the amino acid extend inward toward the core of the helix
Amino acids are the building blocks of the body's proteins. Which statement concerning amino acids is false?
There are approximatly 200 standard amino acids that occur naturally in the proteins of the human body
Which statement about RNA codons is not true?
Three codons are "start" codons, signaling the start of protein synthesis.
Which of the following best describes the primary function of mRNA in a cell?
To transcribe the instructions for protein synthesis from DNA and carry this information to the ribosomes
What step in the synthesis of proteins involves the genetic message contained in mRNA specifying the specific amino acid sequence of a protein?
Translation
Based on its name, which compound is an enzyme?
Triosephosphate isomerase
Which choice is the unique structural feature of collagen?
Triple helix
Which of the following is the name of the nucleoside formed from D-ribose and cytosine?
cytidine
Which is not a type of RNA molecule?
dRNA
Which nucleotide abbreviation is not valid?
dUMP
The three key elements needed to form recombinant DNA are: a DNA molecule into which a new DNA segment will be inserted; an enzyme that cleaves DNA at specific locations; and an enzyme from a second organism that will be inserted in the original DNA molecule.
false
The α-helix and the β-pleated sheet are examples of the tertiary structure of a protein.
false
There was a mix-up in the hospital nursery and there is a question as to which baby belongs to a set of new parents. The given gel contains the DNA fingerprint of the new mother (Lane 1), the new father (Lane 2), and two infants (Lanes 3 and The DNA fingerprinting indicated that the infant tested in Lane 4 is the child of these parents
false
When the base guanine is added to the 2'-OH of the monosaccharide ribose, the product is guanosine.
false
When the peptide below is hydrolyzed with water, the products are the amino acids proline, cysteine, and glutamine.
false
What is the charge on a zwitterion?
neutral
Which is the smallest type of RNA?
tRNA
A diet of rice and tofu provides all essential amino acids
true
A gene is a portion of a DNA molecule responsible for the synthesis of a single protein.
true
A virus that contains a core of RNA is called a retrovirus
true
Acidic amino acids have lower pI values than basic amino acids.
true
Almost any type of cell—skin, saliva, semen, blood, etc.—can be used to obtain a DNA fingerprint of an individual.
true
Amino acids with an additional COOH group in the side chain are classified as acidic amino acids.
true
By convention, the C-terminal amino acid is always written at the right end of the peptide chain and the N-terminal amino acid at the left
true
During replication, the two strands of DNA separate and each serves as a template for a new strand. Thus, the original DNA molecule forms two DNA molecules, each of which contains one strand from the parent DNA and one new strand.
true
Globular proteins are coiled into compact shapes with hydrophilic outer surfaces that make them water-soluble.
true
Hydrogen bonding is possible between the side chains of the amino acids tyrosine and threonine.
true
It is possible for two different proteins to contain the same number and type of amino acids.
true
No one plant source has sufficient amounts of all of the essential amino acids
true
No one plant source has sufficient amounts of all of the essential amino acids.
true
Nucleic acids are formed by joining the 3'-OH group of one nucleotide with the 5'-phosphate of a second nucleotide in a phosphodiester linkage
true
