Microbiology Chapter 9

A nucleotide is oriented 5' or 3' depending on the location of the _______ on the strand of DNA.

deoxyribose carbons

During transcription _______, RNA polymerase moves along the DNA strand, adding complementary nucleotides to the mRNA strand.

elongation

Which of the following occurs during translation termination?

enzymatic breaking of bond between tRNA and polypeptide chain

A cell with an integrated F factor transmits its genes at lower frequency than does a cell with a free plasmid in the cytoplasm..

false

The mechanisms of transformation involve genes that can regulate cellular genomes and control the onset of cell division.

oncogenic

Viruses that lead to the transformation of the host cell into a cancer cell are described as being ____________.

oncogenic

Which part of the control locus acts as an on/off switch for transcription?

operator

The site on a chromosome where DNA replication begins is called the_________ of replication

origin

Mutations that involve the addition, deletion or substitution of no more than a few bases are referred _______ mutations

point

The trp operon consists of ________ structural gene(s).

five

The replication ___________is the Y-shaped point on a replicating DNA molecule where the DNA polymerase is synthesizing new strands of DNA.

fork

Which DOES NOT occur during translation elongation?

formyl methionine is delivered to the ribosome enzymatic breaking of bond between tRNA and polypeptide chain

There are approximately 4,200 genes ____________ in the chromosome of Escherichia coli.

genes

When one bacterium donates DNA to another bacterium, a type of genetic recombination known as _________ has occurred.

horizontal gene transfer

result from exposure to known mutagens, which are primarily physical or chemical agents that damage DNA

induced mutation

Lactose acts as an

inducer

are DNA sequences found within a gene that do not encode the protein corresponding to the gene.

introns

The final sealing of nicks in a newly synthesized DNA strand is catalyzed by the enzyme ______

ligase

Which molecule contains the codons for the polypeptide?

mRNA

The RNA form that contains the transcribed code for a protein from the original DNA strand is ______________RNA.

messenger

The three types of RNA are?

messenger RNA, transfer RNA, ribosomal RNA

Which is an agent that induces changes in DNA?

mutagen

A permanent inheritable alteration in the DNA sequence of a cell is a(n)

mutation

Genetic ______ and the variations they produce result in population changes and thus, evolution.

mutations

A ______ mutation results in early termination of the protein.

nonsense

The termination of transcription involves ______.

separation of RNA from the DNA template

Short lengths of RNA called ________ have the ability to control the expression of certain genes.

small interfering RNA (siRNA)

highly specific part of the host genome is regularly incorporated into the virus

specialized transduction

the__________codon AUG of mRNA is associated with the tRNA anticodon UAC and the amino acid methionine.

start

The mRNA sequence AUG, specifying the first amino acid in protein sequences, is called the

start codon

The term _________or codon, is a sequence of 3 nucleotides in DNA that encodes an amino acid.

triplet

The protein product of a repressor gene is the ________which binds the operator to stop transcription.

repressor

the ________protein is capable of repressing an operon.

repressor

During _____________DNA replication, the newly made double helices are composed of one parent template and one newly synthesized strand.

semiconservative

Which is true regarding DNA replication?

Each new DNA helix contains one parent strand and one newly synthesized strand

The accuracy of DNA replication is important because mutations in the DNA are always detrimental to the survival of an organism.

False

A codon contains how many nucleotides?

3

A(n) ______ is a sequence of DNA nucleotides that codes for one functional protein or RNA.

Gene

Which enzyme completes the final sealing of nicks in a newly synthesized DNA strand?

Ligase

Which type of plasmids confer the ability of an organism to survive treatment by antibiotics?.

R factors

Which of the following best describes translation?

RNA to protein

What must occur prior to cell division to ensure that each new cell has a complete set of DNA chromosome(s)?

Replication

Which are parts of the lactose operon?

Structural locus Control locus Regulator

are the three stop codons within the genetic code.

UAG UAA UGA

How do an Hfr cell and an F+ cell differ?

The plasmid is integrated into the chromosome of an Hfr cell but not in an F+ cell.

True or false: During DNA replication, both the leading and lagging strands are synthesized in the 5' to 3' direction.

True

In RNA, which nitrogenous base pairs with adenine?

Uracil

Any nitrogen-containing molecule found in DNA and RNA that provides the basis for the genetic code is a nitrogenous

base

A mutation that causes a change in a single nucleotide in DNA

changes the corresponding nucleotide in mRNA, resulting in a different codon.

A ______ is a discrete cellular structure composed of a neatly packaged DNA molecule.

chromosome

In eukaryotic cells, what cellular structure is composed of a neatly packaged DNA molecule?

chromosome

A ________ is the specific sequence of 3 mRNA nucleotides, based on a DNA triplet, that encodes a particular amino acid.

codon

Donor and recipient bacterial cells are connected by the sex pilus during

conjugation

Protein synthesis takes place in (on) the _______ of eukaryotic cells.

cytoplasm

Transcription occurs in the __________ bacteria and the _________ of yeast cells.

cytoplasm ; nucleus

in eukaryotic cells, gene expression is regulated in response to __________stimuli such as nutrient and toxin levels, and also during growth and _______________

environmental ; development

In eukaryotes, which DNA sequences encode functional protein?

exons

are DNA sequences which encode for functional proteins.

exons

In bacterial conjugation, all F+ donor cells are high frequency recombinant (Hfr) cells.

false

In the presence of tryptophan, transcription of the trp operon is on.

false

Mutations are always harmful to cells.

false

One reason mutations are so problematic is that bacterial cells have no ability to repair a mutation once it has occurred.

false

Transformation is a mode of genetic recombination in which a plasmid is transferred from a donor cell to a recipient cell via a direct connection.

false

Viral genomes are always composed of either single or double stranded DNA.

false

After a eukaryotic mRNA has been transcribed, _______ are removed.

introns

An inversion

is the flipping of a DNA segment.

Replication

is the process of making an exact copy of DNA.

The newly forming DNA strand that is discontinuously replicated in segments (Okazaki fragments) is called the

lagging

Which strand is replicated discontinuously in segments during DNA replication?

lagging

The ____________or continuous, strand is replicated without segments during DNA replication.

leading

Which of the following types of RNA is the transcribed version of a structural gene in DNA, that is later read for translation into protein?

mRNA

During eukaryotic protein synthesis, ______ ribosome(s) are used to translate mRNA that contains ______ gene(s).

many , one

Transcribed version of a structural gene or genes in DNA

messenger RNA

The basic unit of DNA structure is a(n):

nucleotide

In a protozoal or fungal cell, chromosomes are located in the

nucleus

random fragments of disintegrating host DNA are taken up by the phage during assembly

generalized transduction

is the study of the inheritance of living things.

genetics or heredity

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

The ______ is the genetic makeup of an organism that is ultimately responsible for an organism's expressed characteristics.

genotype

Several DNA viruses are known to be initiators of cancers and are thus termed

oncogenic

unwinds DNA strands.

helicase

The characteristics resulting from the interaction of the particular genetic makeup of an organism and the environment is the ______________ of that organism.

phenotype

The expression of the genotype creates traits referred to as the

phenotype

A DNA nucleotide is composed of a(n)

phosphate, deoxyribose sugar , nitrogen base.

Which process repairs DNA that has been damaged by ultraviolet radiation using visible light? Multiple choice question.

photoactivation

What is the term for the gene that codes for a protein capable of repressing the operon?

regulator

genes control gene expression.

regulatory

-ssRNA viruses

poliovirus

The enzymes responsible for building the DNA strand, proofreading newly produced DNA strands, and removing the RNA primer are DNA________________

polymerase

The initiation of transcription occurs when RNA polymerase recognizes and binds to a region of DNA called the______ region

promoter

_____________operons often contain genes coding for anabolic enzymes and are usually turned off by the end product of the reactions catalyzed by these enzymes.

repressible

Which are components of an operon in a sequence of DNA?

structural genes operator

changing of single base in the DNA code that may result in the placement of a different amino acid

substitution mutation

The region of DNA that signals the end of an RNA transcript is the________ sequence

termination

How many stop codons are contained within the genetic code?

three

are able to shift from one part of the genome to another.

transposons "Jumping genes" are known as

The native or _____ type strain exhibits nonmutated characteristics.

wild type

Two subunits of the __________comprise the site of protein synthesis.

ribosome

Two units of the ___________comprise the site of protein synthesis.

ribosome

Due to the separation of prophage DNA from the bacterial chromosome, a specific, adjacent part of the host genome is transferred during _____________ transduction

specialized

Which enzyme unzips the DNA helix prior to the start of replication?

Helicase

Which pentose sugar is found in RNA?

Ribose

test is used to determine the carcinogenic potential of a chemical.

ames

The lactose operon is composed of the regulator, the ______ locus, and the structural locus.

control

Please select all of the characteristics of DNA to test your understanding of its chemical structure.

deoxyribose sugar phosphate group nitrogenous base

A point mutation results from an insertion or deletion of nucleotides, and always leads to a shift of the triplet sequence from the point of mutation downstream.

false

Bacterial conjugation is a sexual process.

false

Codons are found on tRNA, and anticodons are found on mRNA.

false

In a repressible operon, excess product acts as a corepressor to increase transcription of the operon.

false

mutation results from an insertion or deletion of nucleotides in multiples of 1 or 2, leading to a shift of the triplet sequence from the point of mutation downstream.

frameshift

which mutation is the most harmful to people

frameshift

The science of heredity is ______.

genetics

is the sum of all the genes constituting an organism's distinctive genetic makeup.

genome

All of the following are methods for detecting mutant bacteria, except ___

gram staining

The _____________ bases are either purines or pyrimidines.

nitrogen

mutation changes an amino-acid-producing codon into a stop codon, leading to premature termination of a protein.

nonsense

Mutations that involve the addition, deletion or substitution of one or a few bases are referred to as _______ mutations.

point

During semiconservative _________ the DNA is duplicated prior to binary fission.

replication

A special type of RNA called _______ remove introns from eukaryotic mRNA sequences.

spliceosomes

genes code for proteins.

structural

When RNA polymerase reaches the _____________site on the DNA template, the newly formed mRNA sequence is released.

termination

Please choose all of the statements that are true regarding transcription and translation in prokaryotes.

-Prokaryotic mRNAs often contain information from several genes in series. -transcription and translation can occur at the same time in prokaryotes. -Translation occurs in the cytoplasm of prokaryotes.

How many replication forks are formed from opening a section of a circular DNA molecule during replication?

2

DNA polymerase_________ is the enzyme responsible for building the DNA strand.

3 or three

Which template DNA sequence encodes the peptide sequence phenylalanine-leucine-aspartic acid-valine? (Look up the genetic code figure in your textbook)

3'-AAAAACCTACAT-5'

During transcription, RNA polymerase synthesizes ______ from a(n) ______ template.

RNA,DNA

Elongated genomes may fit inside the minuscule volumes of a cell because of the complex _____ of the DNA molecule

coiling, packaging, or folding

What is the result of a point mutation that changes a template gene sequence from 3'-TACGCCATATAT-5' to 3'-TACGCCATCTAT-5'?.

nonsense mutation

For DNA viruses, the virus cycle occurs in the ____________, whereas the virus cycle for RNA viruses occurs in the ___________.

nucleus; cytoplasm

Which are components of an operon in a sequence of DNA?

operator structural genes

Two components of an operon include the _____that acts as an on/off, and the ______ gene sequences

operator,structural

Prokaryotic DNA is arranged into systems called

operons

s a small circular segment of DNA found in the cytoplasm of bacteria that is capable of independent replication and usually contains nonessential genes.

plasmid

The ________ of an operon is the location where RNA polymerase binds, whereas the _________ acts as the on/off switch for transcription of the structural genes.

promoter; operator

DNA polymerases are responsible for

proofreading/repair. building the DNA chain.

RNA may exert control on several levels in both prokaryotes and eukaryotes.

regulatory

Retroviruses, such as the human immunodeficiency virus (HIV), carry their genetic information as RNA and convert it to DNA using the enzyme

reverse transcriptase

forms a complex cellular structure that contributes to the process of translation

ribosomal RNA

Mutant bacteria may be detected by utilizing

selective media replica plating differential media

Which type of mutation is due to random mistakes in replication?

spontaneous

The region of DNA that signals the end of an RNA transcript is the _____ sequence

terminator

What region of DNA signals the end of a RNA transcript?

terminator

In the presence of tryptophan, tryptophan binds to the

trp repressor.

A structural gene encodes the information for a specific protein.

true

The promoter of an operon is the location where RNA polymerase binds, whereas the operator acts as the on/off switch for transcription of the structural genes.

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.

Which of the following are functions of RNA polymerase?

Unwinds the DNA so that transcription can take place Synthesizes an RNA molecule from DNA template

addition or deletion of bases that changes the reading of mRNA codons

frameshift mutation

random change in the DNA arising from errors in replication that occur without a known cause

spontaneous mutation

The amino acid sequence of a protein determines its shape and specific function.

true

A strand of mRNA is constructed in the_________ direction

5' to 3'

DNA mutations are passed on to a cell's progeny.

true

A mutation that changes a single nucleotide can result in a different amino acid being added into a protein.

true

All viruses require the use of host cell ribosomes and host cell tRNA to translate viral mRNA into viral proteins.

true

An operon is a group of genes that is under the control of a singe operator site.

true

R-factors or "resistance factors" can be shared between bacteria through conjugation to help them survive the effects of antibiotics.

true

The lac operon is normally in an off mode and does not initiate enzyme synthesis when the appropriate substrate is absent.

true

The lac repressor protein is active in the absence of lactose within the cell.

true

Which nitrogenous base is found in RNA but not found in DNA?

Uracil

Nucleotides can only be added to the ____ end of a growing chain.

3'

In bacterial conjugation, which type of donor has the fertility factor integrated into the chromosome?

Hfr

In a chromosome, the DNA is composed of ______ strands.

2

Please order the following stages of DNA replication in the proper order from first to last as it occurs in prokaryotic cells.

-uncoiling of the parent DNA molecule -unzipping the hydrogen bonds between the base pairs -synthesis of two new DNA strands -two DNA molecules, each with one old and one new strand

Put the following steps in order describing the viral process of a retrovirus, such as HIV.

-viral RNA -single- stranded DNA - double stranded DNA -new viral RNA

In DNA, adenine pairs with thymine whereas cytosine pairs with guanine

..

Please order the following to represent the stages from beginning to end of the transcription process.

1-RNA polymerase binds to the promoter region on the DNA strand. 2-RNA polymerase builds the mRNA strand based on the DNA sequence. 3-RNA polymerase dissociates from the DNA strand at a specific sequence.

Which is true regarding adenine and guanine?

Both are purines

What is the function of tRNA?

Brings amino acids to the ribosome

Which component of DNA determines the 3' and 5' ends of the strands?

Carbons in the deoxyribose sugar

Eukaryotic chromosomes are composed of ___

DNA

Genes are made up of ______, a macromolecule made up of nucleotides.

DNA

Which best describes the flow of genetic information in a cell?

DNA encodes RNA which encodes protein

synthesized new DNA strands.

DNA polymerase

The flow of genetic information in a cell is a process starting with __________ which encodes ____________ which encodes

DNA, Messenger RNA

Which of the following best describes transcription?

DNA-RNA

Which pentose sugar is found in DNA?

Deoxyribose

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 located in the cytoplasm?

F+

In bacterial conjugation, which term refers to a recipient cell that does not have a fertility plasmid?

F-

Genetic inheritance in microorganisms is best defined by which term?

Heredity

is another term for genetics--the study of inheritance in living things.

Heredity

dsDNA virus

Herpesvirus

DNA polymerase ____ is the main enzyme involved in the building of the new DNA chain, whereas DNA polymerase ____ is involved mostly with removing the primers and repairing damaged DNA.

III,I

Where are the chromosomes of yeast cells located?

In the nucleus (eukaryotic chromosomes are enclosed by a nucleus)

Which type of operon is typically in the "off" position until the appropriate substrate is present?

Inducible operon

What amino acid sequence is encoded by the DNA template sequence 3'-TACCGCGCTCTACCG-5'?

Methionine-Alanine-Arginine-Aspartic Acid-Glycine

Which of the following are parts of a nucleotide in DNA?

Nitrogenous base Deoxyribose sugar Phosphate

fragments are formed during DNA replication of the lagging strand.

Okazaki

The enzyme that accomplishes transcription is termed

RNA Polymerase

The large enzyme complex involved in synthesizing RNA from a DNA template is called

RNA Polymerase

The main enzyme responsible for transcription is

RNA Polymerase

The large enzyme complex involved in synthesizing RNA from a DNA template is which of the following?

RNA polymerase

Which of the following is the genetic pattern of viral genomes?

Single or double stranded DNA or RNA

A mutation is an alteration in the DNA sequence or content of a cell that is passed on when the cell divides.

TRue

Which of the following describes the primary structure of a protein?

The chain of amino acids bound by peptide bonds

The nitrogenous bases found in DNA include:

Thymine Guanine Adenine Cytosine

Which term, synonymous with codon, describes a trinucleotide sequence coding an amino acid in DNA?

Triplet

DNA is the blueprint that indicates which kinds of proteins to make and how to make them.

True

Transcription elongation involves ______.

adding of nucleotides to the growing mRNA chain

The _______ of tRNA is complementary to the mRNA codon in translation.

anticodon

The tRNA_______is complementary to the mRNA codon.

anticodon

The _______ of a tRNA is complementary to a __________ of mRNA

anticodon , codon

In the absence of tryptophan, the trp repressor is

inactive and cannot bind to the operator.

A(n) operon such as the lac operon, is usually in the "off" position, but can be turned on when the appropriate substrate is present.

inducible

mutation results in a different amino acid being incorporated into a protein, with varying results.

missense

A(n) _______ is a section of prokaryotic DNA that contains one or more genes along with a corresponding operator to control transcription.

operon

The specific order of amino acids bound to each other by peptide bonds represents the __________ structure of protein

primary

During replication initiation, the enzyme___________synthesizes primer sequences.

primase

Which type of organisms have their DNA arranged into operons?

prokaryotes

RNA polymerase binds to the_____region to initiate transcription.

promoter

Which organic molecule is formed from chains of amino acids?

protein

are functional biomolecules in cells formed from one or more long chains of amino acids.

proteins

In DNA a purine always combines with?

pyrimidine

thymine, cytosine, and uracil are

pyrimidines

Which type of RNA comprises ribosomal subunits?

rRNA

Which recombination method involves transfer of DNA via bacteriophages?

transduction

RNA brings amino acids to ribosomes

transfer

contains the anticodon and an amino acid binding site

transfer RNA

The acceptance by a bacterial cell of small DNA fragments from the surrounding environment is termed

transformation

involves the uptake of free DNA by competent bacterial cells.

transformation

During which process is mRNA converted into a protein?

translation

A _____binds to an inactive repressor to make an active

corepressor

Carbohydrates

are sugars and do not contain amino acids, the building blocks of proteins.

Which of the following is NOT a result of transposon activity in bacteria?

correction of ultraviolet radiation mutations

synthesizes RNA during transcription.

RNA polymerase

Which term refers to the transfer of genes from donor to recipient microorganisms?

recombination

All new DNA strands are synthesized from

5' to 3'

Retrovirus

HIV

The enzyme involved in replicating a new DNA strand is DNA polymerase _____, and DNA polymerase _____ is involved in removing the RNA primer, closing gaps, and repairing mismatched bases.

III, I

Which best describes the antiparallel orientation of strands in DNA?

One strand is 5' to 3' and the other is 3' to 5'.

What region of DNA signals the end of a RNA transcript?

Terminator

Initiation of transcription involves ______.

binding of RNA polymerase to promoter region

Nucleotides are the building blocks of

both DNA and RNA

operons are usually turned on by the substrate of the enzyme for which the structural genes code.

inducible

Which type of operon is typically in the "off" position until the appropriate substrate is present?

inducible operon

Which is the correct order of events in transcription?

initiation elongation termination

Which DNA sequences are found within a gene but do not encode the protein specified by that gene?

introns

Transduction

is a form of genetic transfer in bacteria.

Anticodon

is a trinucleotide sequence in tRNA

Transcripton

is the process of converting DNA into RNA. is the process of decoding DNA into messenger RNA.

DNA_________synthesizes DNA strands in the 5' to 3' direction.

polymerase

RNA polymerase binds to which region of DNA to begin transcription?

promoter

The transcription enzyme first attaches to the ________ of the gene.

promoter

Which occurs during translation elongation?

tRNA delivers amino acid to empty A site formation of peptide bond between amino acids in A and P sites translocation of ribosome