Chapter 12 Microbiology

As prokaryotes normally only have one set of genes, they are called __________.  

The __________ is the collection of characteristics of an organism that an investigator observes.  

The __________ describes the specific set of genes an organism possesses.  

Which of the following individuals or groups of individuals demonstrated that the transforming principle was DNA?  

• A.

  Avery, MacLeod, and McCarty

• B.

  Griffith

• C.

  Hershey and Chase

• D.

  Watson and Crick

The principle of transformation was first demonstrated by which of the following individuals or groups of individuals?  

• A.

  Avery, MacLeod, and McCarty

• B.

  Griffith

• C.

  Hershey and Chase

• D.

  Watson and Crick

Hershey and Chase demonstrated that when the bacteriophage T2 infected its host cell, the __________ is injected into the host but the __________ remained outside.   (answer, answer)  

DNA functions as a storage molecule, holding genetic information for the lifetime of a cellular organism and allowing that information to be duplicated and passed on to its progeny.  

• A.

  True

• B.

  False

The genetic information in DNA is divided into units called  

• A.

  Proteins

• B.

  Genes

• C.

  Genotype

• D.

  Phenotype

The two strands of a DNA molecule are __________; that is, they are oriented in opposite directions.  

The B form of the DNA double helix contains a wider major groove and a narrower minor groove because the two polynucleotide strands are not positioned directly opposite one another in the helical cylinder.  

• A.

  True

• B.

  False

The basic differences between RNA and DNA reside in their sugar and pyrimidine bases; RNA has ribose and uracil whereas DNA has deoxyribose and thymine.  

• A.

  True

• B.

  False

Which of the following is not a pyrimidine?  

• A.

  Adenine

• B.

  Cytosine

• C.

  Thymine

• D.

  Uracil

Which of the following is not a complementary base pair usually found in DNA molecules?  

• A.

  Adenine-thymine

• B.

  Guanine-cytosine

• C.

  Adenine-uracil

• D.

  All of the choices

Which of the following is true about the structure of DNA?  

• A.

  Purine and pyrimidine bases are attached to the 1'-carbon of the deoxyribose sugars.

• B.

  Purine and pyrimidine bases are joined by phosphodiester bonds.

• C.

  Adjacent bases are stacked on top of each other, one base pair every 0.34 nm. 


• D.

  All of the choices

Which of the following nitrogenous bases is usually found in RNA but not in DNA?  

• A.

  Adenine

• B.

  Thymine

• C.

  Uracil

• D.

  Guanine

DNA replication is a complex process, and as a result the frequency of error is quite high.  

• A.

  True

• B.

  False

Because of its larger size, the replication rate of eukaryotic genomes is significantly faster than the replication rate of prokaryotic genomes.  

• A.

  True

• B.

  False

Bacterial chromosomes, unlike eukaryotic chromosomes, often consist of a single replicon.  

• A.

  True

• B.

  False

When a DNA molecule is replicated, the daughter molecules contain one strand of parental DNA and one strand of newly synthesized DNA; this is called __________ replication.  

• A.

  Hemiconservative

• B.

  Conservative

• C.

  Semiconservative

• D.

  Dispersive

The chromosomes of most bacteria are comprised of  

• A.

  Double-stranded circular molecules

• B.

  Double-stranded linear molecules

• C.

  Single-stranded circular molecules

• D.

  Single-stranded linear molecules

The Y-shaped part of the DNA molecule where the actual replication process occurs is called the replication __________.  

• A.

  Tongue

• B.

  Fork

• C.

  Junction

• D.

  Splice

Each chromosome has one or more __________ site(s) where replication begins.  

• A.

  Promoter

• B.

  Replicon

• C.

  Origin

• D.

  Bifurcate

During replication the 2 strands of the DNA molecule are unwound from one another by enzymes called  

• A.

  Ligases

• B.

  Unwindases

• C.

  Helicases

• D.

  Primases

Over twisting or under twisting of helical DNA generates  

• A.

  Hypertwists

• B.

  Hypotwists

• C.

  Hypercoils

• D.

  Supercoils

Prokaryotic DNA replication occurs at a rate of  

• A.

  750–1,000 base pairs per second

• B.

  750–1,000 base pairs per minute

• C.

  50–100 base pairs per second.

• D.

  50–100 base pairs per minute.

The coding sequence in the DNA of __________ is normally continuous; that is, it is not interrupted by noncoding sequences.  

• A.

  Prokaryotes

• B.

  Plants

• C.

  Mammals

• D.

  Most insects

Which of the following is not considered the final product of the expression of a gene?  

• A.

  A polypeptide chain

• B.

  An mRNA molecule

• C.

  A tRNA molecule

• D.

  An rRNA molecule

The transcribed, but not translated, sequence that is immediately upstream of the region and encodes the functional product is called the __________ region.  

• A.

  Leader

• B.

  Promoter

• C.

  Coding

• D.

  Trailer

The region at which the RNA polymerase binds is the __________ region.  

• A.

  Leader

• B.

  Promoter

• C.

  Coding

• D.

  Trailer

The transcribed and translated region of a gene is the __________ region.  

• A.

  Leader

• B.

  Promoter

• C.

  Coding

• D.

  Trailer

Which of the following is in the coding region of a gene?  

• A.

  Promoter

• B.

  Leader

• C.

  Trailer

• D.

  None of the choices

The unexpressed regions of split genes are called  

• A.

  Exons

• B.

  Endons

• C.

  Introns

• D.

  Codons

A bacterial __________ is the nontranscribed region of the DNA to which RNA polymerase binds in order to initiate transcription.  

• A.

  Operon

• B.

  Operator

• C.

  Promoter

• D.

  Initiatior

A section of DNA that codes for a protein or other functional product is called a(n)  

• A.

  Codon

• B.

  Gene

• C.

  Replicon

• D.

  Anticodon

The strand of DNA for a particular gene that is copied by the RNA polymerase to form mRNA is called the __________ strand.  

• A.

  Leading

• B.

  Template

• C.

  Transcription

• D.

  Copy

Split or interrupted genes have been found in eukaryotes but not in prokaryotes.  

• A.

  True

• B.

  False

The genetic code is usually translated in a nonoverlapping fashion.  

• A.

  True

• B.

  False

A consensus sequence in the untranslated leader sequence of a prokaryotic mRNA which serves as a ribosome binding site is called the _____ - _____ sequence.  

mRNA molecules have a nontranslated sequence called the __________ , which is located downstream of the termination codon.  

On mRNA molecules, a nontranslated sequence called the ___________ usually precedes the initiation codon.  

Splicing of eukaryotic heteronuclear RNA is catalyzed by ______________.  

 Messenger RNA molecules that direct the synthesis of more than one polypeptide are said to be __________.  

In eukaryotes a so-called cap consisting of __________ is attached to the 5' end of the molecule during posttranscriptional modification of hnRNA to produce functional mRNA.  

Eukaryotic mRNAs are modified by addition of a poly(A) sequences at the 3' end and 7-methyl guanosine at the 5' end.  

• A.

  True

• B.

  False

The noncoding sequences located between the start codon and the stop codon in interrupted genes are called introns.  

• A.

  True

• B.

  False

The protein coding sequences in interrupted genes are called exons.  

• A.

  True

• B.

  False

Posttranscriptional modifications that yield eukaryotic mRNAs include which of the following?  

• A.

  splicing to remove introns

• B.

  5' poly (A) tracts 


• C.

  3' caps

• D.

  All of the choices

RNA polymerase III of eukaryotes is responsible for transcribing  

• A.

  RRNA

• B.

  MRNA

• C.

  TRNA

• D.

  All of the above

RNA polymerase II of eukaryotes is responsible for transcribing  

• A.

  RRNA

• B.

  MRNA

• C.

  TRNA

• D.

  All of the above

The Pribnow box of E. coli  

• A.

  Is centered approximately 35 bp upstream of the start site of transcription

• B.

  Is centered between 7 and 13 bp upstream of the start codon

• C.

  is centered approximately 10 bp upstream of the start site of transcription

• D.

  is located at the site of addition of poly (A) in eukaryotic mRNAs