Clinical Microbiology Exam 1 (CH 9)
tRNA that has released the amino acid it carried, leaves the ribosome through the ___ site
E
Which type of donor has the fertility factor integrated into the chromosome in bacterial conjugation
Hfr
Which type of donor has the fertility factor integrated into the chromosome in bacterial conjugation?
Hfr
The enzyme involved in replicating a new DNA strand is DNA polymerase _____ while DNA polymerase ____ is involved in removing the RNA primer, closing gaps, and repairing mismatched bases
III I
How does RNA differ from DNA?
In RNA, uracil replaces thymine RNA is single stranded
Which type of plasmids confer the ability of an organism to survive treatment by antibiotics?
R factors
In e.coli, DNA polymerase I removes the ___ primers and replaces them with ___
RNA DNA
The main enzyme responsible for transcription is
RNA polymerase
How do and Hfr cell and a F+ cell differ?
The plasmid is integrated into the chromosome of an Hfr cell but not in an F+ cell
What is the purpose of the Ames test?
To determine the carcinogenic potential of a chemical
A donor cell typically copies the F factor before transferring it to another cell
True
What is a riboswitch?
a region within an mRNA that regulated the translation of the mRNA of which they are a part of
In simple transposition,
a transposable element is removed from its original site and inserted at another location
Methicillin-resistant Staphylococcus aureus (MRSA) strain produces vancomycin resistant enterococci (VRE) with the gene transfer of ______.
a transposon containing the vanA operon
A recombinant is any organism that has
acquired genes that originated in another organism
The carcinogenic potential of a chemical can be determined by the ____ test
ames
The ___ of a tRNA is complementary to a _____ of mRNA
anticodon codon
During which method of gene transfer are bacteria cells in direct contact?
conjugation
Protein synthesis takes place in the ____ of eukaryotic cells
cytoplasm
Transcription occurs in the ____ of bacteria and the ______ of yeast cells
cytoplasm (bacteria) nucleus (yeast cells)
When using an organism that has lost the ability to synthesize histidine in the Ames test, which outcome would show that a chemical is a mutagen?
enhances the rate of back mutation to cells that can synthesize histidine
Proteins contribute to the phenotype of an organism by functioning as
enzymes structural molecules
Chromosomes are wound twice around histone proteins, creating a chain of nucleosomes, in ___
eukaryotes
Chromosomes are wound twice around histone proteins, creating a chain of nucleosomes, in _____
eukaryotes
One DNA repair mechanism that removed incorrect bases, and replaces them with correct ones, i s the ___ repair mechanism
excision
Viral genomes are always composed of either single or double stranded DNA
false
A cell with an integrated F factor transmits its chromosomal genes at lower frequency than does a cell with a free plasmid in the cytoplasm
false high frequency recombination (Hfr)
A mutation that results from an insertion or deletion of a number of nucleotides that is not a multiple of 3, leading to a shift of the triplet sequence from the point of mutation downstream is an ______
frameshift
Mutations that are generally most harmful to cells because they cause the greatest change in the amino acid sequence of a protein are ____ mutations
frameshift
Which of the following are caused by chemical mutagens?
frameshift mutations base substitution
Random portions of host DNA are transferred by bacteriophage during ______ transduction
generalized
There are 4.288 ____ in the chromosome of e.coli
genes
The study of the inheritance in living things is
genetics
The complete set of chromosomes and genes in an organism is referred to as the
genome
Which term represents all of the genetic information within a cell?
genome
Which strand is replicated continuously, without segments, during DNA replication?
leading
During eukaryotic protein synthesis, ____ ribosomes are used to translate mRNA that contains _____ gene(s)
many one
The three types of RNA that are directly involved in making protein are ____ RNA,______ RNA, and _____ RNA
messenger transfer ribosomal
A mutation that results in a different amino acid being incorporated into a protein, with varying results, is a _____ mutation
missense
Which type of mutation results in a different amino acid being incorporated into a protein?
missense
During transposition, small segments of DNA
more themselves to new locations within chromosomal DNA
During transposition, small segments of DNA _____
move themselves to new locations within chromosomal DNA
An agent that induces changed in DNA is a
mutagen
An alteration in the DNA sequence of a cell is an
mutation
A small number of ____ are considered beneficial in that they provide the cell with a useful change in structure or physiology
mutations
RNA viruses with a single ____ strand genome must be converted to _______ strand genome before translation
negative positive
Which of the following are chemicals that cause mutations?
nitrous acid acridine dyes ethidium bromide
When the F factor is transferred by e.coli
no additional donor genes are transferred
Which mutation changes an amino acid-producing codon into a stop codon
nonsense
In the cells of protozoa, fungi, animals, or plants, chromosomes are located in the ____
nucleus
Alternations to a protein made after translation, such as removal of f-met, addition of cofactors, and joining with other proteins for quaternary structure, are referred to as ____ modifications
posttranslational
A special enzyme called a topoisomerase packages chromosomes into a tight bundle in_____
prokaryotes
Which type of organism have their DNA arranged into operons?
prokaryotes
To initiate transcription, RNA polymerase binds to the _____ region of DNA
promoter
the DNA blueprint specifies how to make what type of macromolecule
protein
A _____ is any organism that has acquired genes that originated in another organism
recombinant
When one bacterium donated DNA to other bacterium, it is known as
recombination
Which term refers to the transfer of genes from donor to recipient microorganisms?
recombination
Some amino acids can be encoded by several different codons. For that reason, we say that the genetic code is _____
redundant or degenerate
Operons that contain genes coding for anabolic enzymes and are usually turned off by the end product of the reactions catalyzed by these enzymes are _____ operons
repressible
Retroviruses contain the enzyme ____ _____
reverse transcriptase
When using an organism that has lost ability to synthesize histidine in the Ames test, a chemical is considered a mutagen if it increases the rate of _____ mutation beyond levels that would occur spontaneously
back
In what way can a riboswitch directly regulate translation?
by changing the shape of the mRNA
A discrete cellular structure composed of a neatly packaged DNA molecule is an
chromosome
The genome of a prokaryotic or eukaryotic cell includes DNA found in which sites? (4)
chromosomes chloroplasts mitochondria plasmids
A bacterial cell described as _____ can accept soluble DNA from the surrounding environment
competent
the newly made double helices are composed of one parent template and one newly synthesized strand as a result of ____ replication
semiconservative
Which of the following is the genetic pattern of viral genomes?
single or double stranded DNA or RNA
During translation initiation, the _____ ribosomal subunit binds to a specific site on the mRNA to start translation
small
Due to the separation of prophage DNA from the bacterial chromosome, a specific, adjacent part of the host genome is transferred during _____ transduction
specialized
An RNA protein complex called a ___ removes introns from eukaryotic mRNA sequences
splicesomes
Mutations in DNA that are caused by random mistakes in replication and are not known to be the result of any mutagenic agent, are _____ mutations
spontaneous
Which type of mutation is due to random mistakes in replication?
spontaneous mutation
The AUG codon of mRNA is associated with the amino acids methionine, but is also an indication to ____ translation
start
Which of the following are functions of RNA polymerase?
synthesizes an RNA molecule from DNA template unwinds the DNA so that transcription can take place
Which strand is replicated discontinuously in segments during DNA replication?
the lagging strand only
The transfer of DNA via bacteriophages is
transduction
Which form of genetic recombination involved DNA transfer that is mediated through the action of bacterial viruses?
transduction
Which recombination method involved transfer of DNA via bacteriophages
transduction
Which recombination method involves transfer of DNA via bacteriophages?
transduction
Griffith's experiment using Streptococcus pneumoniae demonstrated the process of _______
transformation
Which gene transfer method involved the uptake of free DNA by competent bacterial cells?
transformation
Genes that are able to shift from one part of the genome to another are
transposons
jumping genes are known as _____
transposons
Which term, synonymous with codon describes a trinucleotide sequence coding an amino acid in DNA
triplet
An RNA virus with a positive-strand genome can be immediately translated into protein
true
Cell death is a common result of mutation
true
Coiling DNA and protein into chromatin makes certain segments more available, and thus is a major control on the expression of certain traits
true
R-factors or resistance factors can be shared between bacteria through conjugation to help them survive the effects of antibiotics
true
Several codons can code for the same amino acid, which is called the redundancy of the code
true
In protein synthesis, eukaryotic and prokaryotic cells show similarities in all of the following EXCEPT the
use of formyl-methionine as the first amino acid number of proteins encoded on a single mRNA
Cells that carry nonmutated DNA are called the _____ type strain
wild
Which of the following are physical, as opposed to chemical agents that can cause mutations
x-rays UV light
Which occur during posttranslational modification?
- proteins join with other proteins to form quaternary structures - formyl-methionine is removed from the start of the polypeptide chain - cofactors are added to proteins destined to become enzymes
A DNA triplet encodes ___ mRNA codon and ____ amino acid
1 and 1
Please put the events of translation in order, starting with the first event at the top of the list
1. the mRNA attaches to the ribosome 2. Two tRNA molecules bring amino acids to the ribosome 3. a peptide bond forms between the amino acids 4. the first tRNA exists at the E site 5. The second tRNA shifts to the P site while the third tRNA enters the A site 6. the process repeats with additional tRNA molecules 7. a stop codon in encountered
The 46 human chromosomes contain approximately ______ times as many genes compared to the single chromosome of E. coli.
5
Nucleotides can only be added to a growing DNA chain in the ___ direction
5 to 3
What did Griffith's experiment using Streptococcus pneumoniae demonstrate?
A nonpathogenic strain of S. pneumoniae transformed into a virulent strain
If a codon of mRNA reads 5'-UUG-3', the tRNA that delivers the amino acid to this location during translation will have an anticodon of 3'- _____-5'
AAC
What is a function of the coiling of DNA and protein into chromatin?
Access to certain segments is regulated
Eukaryotic chromosomes are composed of ______.
DNA
Genes are specific segments of ____
DNA
The "blueprint" information for the production of proteins is encoded and stored in section of
DNA
The genome of a cell is entirely composed of
DNA
Which best describes the flow of genetic information in a cell?
DNA encodes RNA which encodes protein
Conjugation in gram-negative cells is directed by a plasmid called the ____ factor
F
What is the name of the specialized plasmid that directs conjugation in gram-negative cells?
F factor
In bacterial conjugation, which term refers to a donor cell with a fertility plasmid?
F+
In bacterial conjugation, which term refers to a recipient cell that does not have a fertility plasmid?
F-
In bacterial conjugation, all F+ donor cells are high frequency recombinant (Hfr) cells
False
During DNA replication, the lagging strand is replicated in a discontinuous manner forming _____ fragments
Okazaki
In translation, mRNA is guided by the ___ and ____ sites on the large ribosomal subunit
P and A
Any alteration in DNA that occurs as a consequence of exposure to chemical or physical mutagens is a(n) ____ mutation
induced
Operons that are usually turned on by the substrate of the enzyme for which the structural genes code are ____ operons
inducible
The smallest transposons, containing only the coding region with transposase and resolvase flanked by terminal inverted repeats, are called
insertion elements
Exposure to chemical mutagens can lead to mutations because chemical mutagens can cause
insertions and deletions during DNA replication inappropriate base pairing during DNA replication
Transposons that carry large blocks of genetic material that transmit drug resistance are called
integrons
The subunit of the ribosome that hold tRNAs and catalyzes peptide bond formation by means of a ribozyme is the _____ subunit
large
Several DNA viruses are known to be initiators of cancers and are thus termed
oncogenic
Viral initiators of cancer are termed
oncogenic
Translation termination occurs when
one of three stop codons is reached by the ribosome
Prokaryotic genes are arranged into systems called _____
operons
Which process uses viable light to repair DNA that has been damaged by ultraviolet radiation?
photoactivation
Donor and recipient bacterial cells are connected by the sex _____ during conjugation
pili
A small circular segment of DNA found in the cytoplasm of bacteria that is capable of independent replication and usually contain nonessential gene is a(n)
plasmid
What is a small circular segment of DNA found in the cytoplasm of prokaryotes that is capable of independent replication and usually contains nonessential genes?
plasmid
A recipient cell having no F (fertility) ____ DNA is considered F- in bacterial conjugation
plasmid or factor
Mutations that involved the addition, deletion, or substitution of one or a few bases are referred to as ___ mutations
point