Clinical Microbiology Exam 1 (CH 9)

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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


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