MCB2010 Microbiology Pretest - Chapter 9

Microorganisms exhibit genomes contained on _______.
A) chromosomes
B) plasmids
C) mitochondrial DNA
D) chloroplast DNA
E) All of the choices are correct depending on the type of microorganism observed.

E) All of the choices are correct depending on the type of microorganism observed.

Eukaryotic chromosomes differ from bacterial chromosomes because only eukaryotes have _______.
A) histone proteins
B) chromosomes in a nucleus
C) several to many chromosomes
D) elongated, not circular, chromosomes
E) All of the choices are correct.

E) All of the choices are correct.

Which of the following is not true of an organism's genotype?
A) It is inherited.
B) It contains structural genes that code for proteins.
C) It contains genes that code for RNA.
D) It has regulatory genes that control gene expression.
E) It has expressed traits governed by the genes.

E) It has expressed traits governed by the genes.

The _____ is all of the genetic material of a cell.
A) chromosome
B) plasmid
C) prophage
D) genome
E) proteome

D) genome

A nucleosome is a linear chromosome wound around the _______.
A) nuclear membrane
B) rRNA
C) mRNA
D) histone
E) nucleolus

D) histone

A ______ is a specific segment of DNA that codes for the production of one functional product.
A) intron
B) exon
C) gene
D) operator
E) triplet

C) gene

The expression of genetic traits is referred to as the organism's ______. A) genome
B) genotype
C) proteome
D) phenotype
E) proteotype

D) phenotype

The DNA of an organism is made up of subunits called _______.
A) histones
B) amino acids
C) nucleotides
D) mRNA
E) polymerases

C) nucleotides

Which is incorrect about purines?
A) They are only found in DNA, not in RNA.
B) They are nitrogenous bases.
C) They are always paired with a specific pyrimidine.
D) They include adenine and guanine.
E) They are found within nucleotides.

A) They are only found in DNA, not in RNA.

All of the following pertain to nitrogenous bases except _______.
A) they form pairs by hydrogen bonding
B) guanine pairs with uracil
C) adenine pairs with thymine
D) cytosine and thymine are pyrimidines
E) they allow variation from one nucleotide to another which creates the encoded information

B) guanine pairs with uracil

Each nucleotide is composed of _______.
A) one phosphate, one nitrogenous base, and one sugar
B) one phosphate, one nitrogenous base, and two sugars
C) two phosphates, one nitrogenous base, and one sugar
D) two phosphates, one nitrogenous base, and two sugars
E) one phosphate, two nitrogenous bases, and one sugar

A) one phosphate, one nitrogenous base, and one sugar

Base pairs in DNA are held together by ______ bonds.
A) peptide
B) nonpolarcovalent
C) polarcovalent
D) hydrogen
E) sulfhydryl

D) hydrogen

The duplication of a cell's DNA is called _______.
A) mitosis
B) replication
C) transcription
D) translation
E) mutation

B) replication

Structural genes code for _______.
A) ribosomal RNA molecules
B) transfer RNA molecules
C) cellular proteins
D) gene expression elements

C) cellular proteins

During replication, each parent DNA strand serves as a ______ for synthesis of new DNA strands.
A) copy point
B) template
C) comparisonmolecule
D) scaffold
E) reservoir

B) template

Semiconservative replication refers to _______.
A) each base bonding at the 1' position of the sugar
B) a purine always bonding to a pyrimidine
C) one helix strand that runs from the 5' to 3' direction and the other strand that runs from the 3' to 5' direction
D) an original parent DNA strand and one newly synthesized DNA strand comprising a new DNA molecule

D) an original parent DNA strand and one newly synthesized DNA strand comprising a new DNA molecule

DNA polymerase III ______.
A) is needed for adding nucleotides during mRNA synthesis
B) synthesizes new DNA only in the 5' to 3' direction
C) cannot add nucleotides to the lagging strand
D) synthesizes an RNA primer

B) synthesizes new DNA only in the 5' to 3' direction

Okazaki fragments are attached to the growing end of the lagging strand by _______.
A) DNA ligase
B) DNA polymerase
C) DNA helicase
D) DNA gyrase
E) primase

A) DNA ligase

The enzyme that helps pack DNA into the cell by coiling the DNA into a tight bundle is _______.
A) DNA ligase
B) DNA polymerase
C) DNA helicase
D) DNA gyrase
E) primase

D) DNA gyrase

The enzyme that can proofread replicating DNA, detect incorrect bases, excise them, and correctly replace them is _______.
A) DNA ligase
B) DNA polymerase
C) DNA helicase
D) DNA gyrase
E) primase

B) DNA polymerase

The site where the old DNA strands separate and new DNA strands will be synthesized is called the ________.
A) primer
B) Okazaki fragment
C) template
D) rolling circle
E) replication fork

E) replication fork

DNA gyrase _______.
A) copies DNA bases
B) synthesizes RNA primers
C) closes gaps between DNA bases
D) removes supercoiling ahead of origin

D) removes supercoiling ahead of origin

Helicase ______.
A) unwinds DNA
B) supercoils DNA
C) unwinds RNA
D) winds RNA

A) unwinds DNA

DNA Polymerase I _______.
A) removes primers
B) adds bases to new DNA chain
C) seals DNA gaps
D) proofreads DNA chain

A) removes primers

DNA Polymerase III _______.
A) synthesizes the primer
B) removes the primer
C) joins Okazaki fragments
D) unzips the DNA helix
E) proofreads new DNA

E) proofreads new DNA

A permanent, inheritable change in the genetic information is called ________.
A) translation
B) transcription
C) a mutation
D) an alteration
E) regeneration

C) a mutation

Replication of DNA begins at a/an _______ rich area.
A) guanine-cytosine
B) uracil-adenine
C) adenine-thymine
D) adenine-cytosine
E) guanine-adenine

C) adenine-thymine

A primer comprised of _______ is needed at the origin of nucleotide addition.
A) polymeraseIII
B) polymerase I
C) helicase
D) RNA
E) DNA

D) RNA

Groups of three consecutive bases along the DNA of a gene have the code for one _______.
A) protein
B) nucleotide
C) amino acid
D) purine

C) amino acid

The three-base sequence on DNA that codes for an amino acid is called a/an ________.
A) codon
B) exon
C) anticodon
D) intron
E) triplet

E) triplet

The RNA molecules that carry amino acids to the ribosomes during protein synthesis are called ________.
A) ribosomal RNA
B) messenger RNA
C) transfer RNA
D) primer RNA
E) ribozymes

C) transfer RNA

Which molecule is translated into an amino acid sequence?2-20-13
A) Ribosomal RNA
B) Messenger RNA
C) Transfer RNA
D) Primer RNA
E) Ribozymes

B) Messenger RNA

RNA molecules differ from DNA molecules because only RNA _______.
A) has ribose
B) has uracil
C) is typically one strand of nucleotides
D) does not have thymine
E) All of the choices are correct.

E) All of the choices are correct.

Which of the following is not a type of microRNA?
A) tRNA
B) miRNA
C) Antisense RNA
D) Riboswitch
E) siRNA

A) tRNA

All of the following pertain to transcription except _______.
A) it occurs on a ribosome in the cytoplasm
B) it occurs before translation
C) it requires RNA polymerase
D) it requires a template DNA strand
E) it is a process that contributes to the synthesis of protein

A) it occurs on a ribosome in the cytoplasm

The nontranscribed region of DNA to which RNA polymerase binds to initiate transcription is called the ________.
A) promoter
B) operator
C) operon
D) exon
E) intron

A) promoter

RNA polymerase binds to the _______.
A) start codon
B) termination sequence
C) regulation sequence
D) promoter sequence

D) promoter sequence

If a codon for alanine is GCA, then the anticodon is ______.
A) GCA
B) CGT
C) ACG
D) CGU

D) CGU

Which of the following is incorrect about termination codons?
A) They are also called nonsense codons.
B) They are the location where the bond between the final tRNA and the polypeptide is broken.
C) They include AUG.
D) They are UAA, UAG, and UGA.
E) They do not have corresponding tRNA.

C) They include AUG.

Which of the following is not associated with a bacterial ribosome?
A) It is a 70s holoenzyme.
B) It has a peptide (P) site.
C) It has an exit site.
D) Its small subunit provides the enzymes for making peptide bonds. E) It has an amino acid (A) site.

D) Its small subunit provides the enzymes for making peptide bonds.

A sequence of bases within a gene that does not code for protein is called a/an _______.
A) promoter
B) operator
C) operon
D) exon
E) intron

E) intron

Split genes _______.
A) are common in bacteria and eukaryotes
B) only have exons initially transcribed to mRNA
C) have introns located only at the beginning and end of a coding region
D) are acted upon by spliceosomes to excise introns and then join exons

D) are acted upon by spliceosomes to excise introns and then join exons

Which is incorrect about inducible operons?
A) They have genes turned off by a buildup of end product.
B) They are often for use in catabolic pathways.
C) They are normally turned off.
D) They are turned on by the substrate of the enzyme.
E) They include the lac operon.

A) They have genes turned off by a buildup of end product.

The operon segment composed of the gene that codes for a protein repressor is called the ________.
A) operator
B) structural locus
C) regulator
D) promoter

C) regulator

Synthesis of an inducible enzyme requires _______.
A) repressor alone bound to operator
B) substrate bound to repressor
C) substrate bound to promoter
D) corepressor and repressor binding to operator

B) substrate bound to repressor

Synthesis of a repressible enzyme is inhibited by _______.
A) repressor alone bound to operator
B) substrate bound to repressor
C) substrate bound to promoter
D) corepressor and repressor binding to operator

D) corepressor and repressor binding to operator

Full induction of the lactose operon requires _______.
A) lactose present
B) lactose and glucose present
C) lactose present without glucose
D) lactose and arabinose present

C) lactose present without glucose

The lactose repressor _______.
A) is transcribed with the structural lac genes
B) is activated by binding lactose
C) is inactivated by binding lactose
D) requires lactose for its transcription

C) is inactivated by binding lactose

Gene regulation can involve a protein repressor that blocks ______ from initiating transcription.
A) DNA polymerase I
B) DNA polymerase III
C) RNA polymerase
D) mRNA
E) rRNA

C) RNA polymerase

Repressible operons require that ______ binds to the repressor protein before it can bind to the operator.
A) the product
B) a cofactor
C) a coenzyme
D) the substrate
E) the reactant

A) the product

A mutation that changes a normal codon to a stop codon is called a ______ mutation.
A) point
B) silent
C) back
D) missense
E) nonsense

E) nonsense

The most serious type of mutation is a ______ mutation.
A) point
B) silent
C) frameshift
D) back

C) frameshift

If the wild type DNA sequence reads THE CAT ATE THE BIG RAT, what type of mutation would change the sequence to THE CAT ATA ETH EBI GRA T?
A) Missense
B) Nonsense
C) Insertion
D) Deletion
E) Silent

C) Insertion

If the wild type DNA sequence reads THE CAT ATE THE BIG RAT, what type of mutation would change the sequence to THE CAT ATE THE BAG RAT?
A) Point
B) Nonsense
C) Insertion
D) Deletion
E) Silent

A) Point

If the wild type DNA sequence reads THE CAT ATE THE BIG RAT, what type of mutation would change the sequence to THE CAT ATE (stop)?
A) Missense
B) Nonsense
C) Insertion
D) Deletion
E) Silent

B) Nonsense

A frameshift is caused by ______ mutations.
A) missense andinsertion
B) missense andnonsense
C) nonsense anddeletion
D) deletion andinsertion
E) insertion andnonsense

D) deletion andinsertion

What type of mutation alters the base but not the amino acid being coded for?
A) Silent
B) Back
C) Point
D) Nonsense
E) Missense

A) Silent

A screening system called the _______ test is used for detecting chemicals with carcinogenic potential.
A) Koch
B) Ames
C) mutation
D) cancer
E) Iowa

B) Ames

The process in which mutations are removed and the correct bases added is called ________.
A) transduction
B) excision repair
C) frameshift
D) back-mutation
E) transformation

B) excision repair

Which cell can transfer the most DNA?
A) F+ cell
B) F- cell
C) Hfr cell
D) R cell
E) B cell

C) Hfr cell

Which of the following is not a type of bacterial DNA recombination?
A) Transformation
B) Conjugation
C) Mitosis
D) Transduction

C) Mitosis

Which of the following is not true of conjugation?
A) Involves direct contact between cells
B) Transfers genes for drug resistance
C) Transfers genes for enzymes and adherence molecules
D) Involves the action of bacteriophage
E) The donor retains a copy of the transferred genes

D) Involves the action of bacteriophage

The transfer of DNA fragments from a dead cell to a live, competent recipient cell that results in a changed recipient cell is termed ________.
A) transduction
B) conjugation
C) transformation
D) transmission
E) mitosis

C) transformation

The development of virulent, toxin-producing bacterial strains due to the presence of a temperate phage can occur through the process of ________.
A) bacterial conjugation
B) transformation
C) generalized transduction
D) specialized transduction

D) specialized transduction

A bacteriophage transfers a random fragment of DNA of the previous host to the current host. This is an example of _______.
A) conjugation
B) generalized transduction
C) specialized transduction
D) the creation of an Hfr cell

B) generalized transduction

The jumping of a gene from one location to another is done by ________.
A) conjugation
B) transposons
C) transformation
D) transduction
E) transmission

B) transposons

Which of the following is not true of transposons?
A) They can change pigmentation.
B) They can replace damaged DNA.
C) They can transfer drug resistance.
D) They can change the genome.
E) They are always part of plasmids.

E) They are always part of plasmids

In Griffith's experiments with Streptococcus pneumoniae, rough nonencapsulated streptococci were converted into smooth encapsulated streptococci in the presence of the heat-killed smooth encapsulated streptococci. Which microbial process had Griffith identified?
A) Transduction
B) Conjugation
C) Transformation
D) Cloning

C) Transformation

Of the following list, which antibiotics affect protein synthesis?
A) Penicillin
B) Tetracycline
C) Chloramphenicol
D) Ciprofloxacin
E) Both tetracyclineand chloramphenicol are correct.

E) Both tetracyclineand chloramphenicol are correct.

The fundamental difference between an organism's genotype and its phenotype is that _______.
A) the genotype refers to all of the genetic material in the organism, whereas the phenotype represents only the genetic material that is expressed into proteins
B) the phenotype refers to all of the genetic material in the organism, whereas the genotype represents only the genetic material that is expressed into proteins
C) the genotype refers to the organism's genes and the phenotype refers to the non-coding segments of DNA
D) the genotype refers to eukaryotic genes that contain both introns and exons, whereas phenotype refers to bacterial DNA that has only exons

A) the genotype refers to all of the genetic material in the organism, whereas the phenotype represents only the genetic material that is expressed into proteins

The field of genomics refers to _______.
A) the study of an organism's complete genome, including plasmid, mitochondrial, and chloroplast DNA
B) the study of an organism's plasmids
C) the study of cellular, but not viral, genomes
D) the study of chromosomal DNA

A) the study of an organism's complete genome, including plasmid, mitochondrial, and chloroplast DNA

The term 'recombinant organism' refers to _______.
A) an organism that expresses proteins coded for by genes that originated in a different organism
B) an organism that has recombined its genes
C) an organism that has genes passed down from the parent cell to the daughter cells during binary fission
D) genetically engineered cells, but not those that have new genes as a result of horizontal gene transfer

A) an organism that expresses proteins coded for by genes that originated in a different organism