Microbiology Chapter 9 Smart Book

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

2

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

2

Step 4 of DNA Replication

2 DNA molecules, each with one old and new strands

A codon contains how many nucleotides?

3

How many stop codons are contained within the genetic code?

3

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

3'

The trp operon consists of ________ structural genes. A) one B) two C) three D) four E) five

5

All new DNA strands are synthesized?

5' to 3'

The mRNA chain is built in the ____________ direction.

5' to 3'

What is the antiparallel orientation of strands in DNA?

5' to 3' and the other is 3' to 5'

Transcription elongation involves?

Adding of nucleotides to the growing mRNA chain.

Uracil, the nitrogenous base unique to RNA molecules, pairs with nitrogenous base?

Adenine

What are the purines?

Adenine and Guanine

What are the four nitrogenous bases?

Adenine, Thymine, Guanine, Cytosine

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

Ames

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

Anticodon

The tRNA __________ is complementary to the mRNA codon.

Anticodon

In DNA, the two strands of the helix are in arranged in ________ orientation.

Antiparallel

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

Base

What is the function of tRNA?

Brings amino acids to the ribosome.

DNA polymerase III is responsible for?

Building the DNA chain

What is the DNA polymerase responsible for?

Building the DNA chain and proofreading/repair.

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

Carbons in the deoxyribose sugar.

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

Changes the corresponding nucleotide in mRNA, resulting in different codon.

A ____________ is a discrete cellular structure 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

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

Coiling

Refers to horizontal gene transmission via pili?

Conjugation

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

Conjugation

A ______________ binds to an inactive repressor to make an active repressor.

Corepressor

The flow of genetic information in a cell is a process starting with _________ which encodes ___________ which encodes protein.

DNA; mRNA

The pentose sugar found in DNA

Deoxyribose

A nucleotide is oriented 5' to 3' depending on the location of the ________ ________ on the strand of DNA.

Deoxyribose carbons

Which of the following are parts of nucelotide in DNA?

Deoxyribose sugar, phosphate, nitrogenous base.

The DNA of a chromosome is?

Double stranded

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

Elongation

Transcription involes initiation,____________, and termination.

Elongation

Which of the following occrus during translation termination?

Enzymatic breaking of bond between tRNA and polypeptide chain.

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

False

Mutations are always harmful to cells.

False

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

False

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

False

The terminator of a gene is located upstream of the coding region.

False

To allow simultaneous replication of the leading and lagging strands by dimeric DNA pol III, the DNA of the leading strand has to be folded.

False

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

False

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 and enzymatic breaking of bond between tRNA and polypeptide chain.

Which type of mutation is generally most harmful to cells?

Frameshift

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

Frameshift mutation

There are approximately 4,200 ________ in the chromosome of E. coli.

Genes

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

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

Genotype

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

Gram staining

Which is a purine?

Guanine

Genetic inheritance in microorganisms is best defined by which term?

Heredity

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

Horizontal gene transfer

DNA polymerase ___ is the enzyme responsible for building the DNA strand.

III

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

In the absence of tryptophan, the trp repressor is?

Inactive and cannot bind to the operator.

Result from exposure to known mutagens, which are pimarily physical or chemical agents that damage DNA

Induced mutation

Lactose acts an ___________ in the lactose operon.

Inducer

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

Inducer

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

Inducible

During eukaryotic protein synthesis, ________ ribosomes are used to translate mRNA that contains ___________ genes.

Many; one

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

Missense

An agent that induces changes in DNA?

Mutagen

A permanent inheritable alteration in the DNA sequence of a cell is a?

Mutation

A small number of ____________ are considered beneficial in that they provide the cell with a useful change in structure or physiology.

Mutations

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

Mutations

The _________ bases are either purines or pyrimidines.

Nitrogen

A ____________ mutation results in early termination of the protein.

Nonsense

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

Oncogenic

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

Oncogenic

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

Operator and structural genes

Two components of an operon include the _____________ that acts as an on/off switch, and the _____________ gene sequences.

Operator/ Structural

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

Operon

Prokaryotic DNA is arranged into systems called?

Operons

The place where DNA replication is intiated is called the?

Origin of replication

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

Phenotype

The expression of the genotype creates traits referred to as?

Phenotype

A DNA nucleotide is composed of a __________, a ____________ sugar, and a __________ base?

Phosphate Deoxyribose Nitrogenous

Which process repairs DNA that has been damaged by ultraviolet radiation using visible light?

Photoactivation

What is a small circular segment of DNA found in the cytoplasm of prokaryotes that is capable of independent replication and usually contain nonessential genes?

Plasmid

An enzyme that is named for its ability to build strands of DNA is DNA?

Polymerase

DNA ___ synthesizes DNA strands in the 5' to 3' direction.

Polymerase

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

Polymerase I and III

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

Proteins

In DNA, a purine always combines with?

Pyrimidine

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

R factors

Step 3 of Transcription

RNA Polymerase dissociates from the DNA strand at a specific sequence.

The enzyme that accomplishes transcription is termed?

RNA polymerase

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

RNA polymerase

What is the main enzyme responsible for transcription?

RNA polymerase

Step 1 of Transcription

RNA polymerase binds to the promoter region on the DNA strand.

Step 2 of Transcription

RNA polymerase builds the mRNA strand based on the DNA sequence.

Which of the following best describes translation?

RNA to protein

During transcription, RNA polymerase synthesizes _______ from a _______ template.

RNA; DNA

Refers to the transfer of genes from donor to recipient microorganisms, where the recipient strain shows a change in genetic makeup at the end.

Recombination

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

Recombination

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

Regulator

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

Regulatory

During semiconservation ___________ the DNA is duplicated prior to binary fission?

Replication

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

Replication

What must occur prior to cell division to ensure that each new cell has a complete set of DNA chromosomes?

Replication

What must occur prior to cell division to ensure that each new cell has complete set of DNA chromosomes?

Replication

Donor and recipient bacterial cells are connected by the?

Sex pili during conjugation

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

Small interfering RNA

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

Specialized transduction

Highly specific part of the host genome is regularly incorporated into the virus.

Specialized transduction

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

Spliceosomes

____________________ mutations in DNA are caused by random mistakes in replication and not known to be influenced by any mutagenic agent.

Spontaneous

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

Spontaneous mutation

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

Start

What kind of gene encodes a protein?

Structural

Which kind of gene encodes a protein?

Structural

What codes for proteins?

Structural genes

Which are parts of the lactose operon?

Structural locus Control locus Regulator

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

Substiution mutation

Step 3 of DNA Replication

Synthesis of 2 new DNA strands

Which of the following are functions of RNA polymerase?

Synthesizes an RNA moleule from DNA template and unwinds the DNA so that transcription can take place.

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

TRUE

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

TRUE

What are the pyrimidines?

Thymine and Cytosine

What is the purpose of the Ames test?

To determine the carcinogenic potential of a chemical.

The process of decoding DNA into messenger RNA.

Transcription

What is the process of decoding DNA into messenger RNA?

Transcription

Which RNA brings the amino acids to the ribosome?

Transfer

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

Transformation

Which gene transfer method involves the uptake of free DNA by competent bacterial cells?

Transformation

During ________, the information in mRNA is used to produce a protein.

Translation

During which process is mRNA converted into a protein?

Translation

Which occurs during translation elongation?

Translocation of ribosome. tRNA delivers amino acid to empty A site. Formation of peptide bond between amino acids in A and P sites.

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

Transposons

In the presence of tryptophan, tryptophan binds to the

Trp repressor

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

True

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

True

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

True

A structural gene encodes the information for a specific protein?

True

An operon is a group of genes that is under the control of a singe operator site. A) True B) False

True

DNA mutations are passed on to a cell's progeny

True

DNA photolyase is a light-sensitive enzyme able to repair DNA damaged by ultraviolet radiation.

True

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

True

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

True

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

True

The polycistronic mRNA is transcribed from the lac operon when lactose is present in the cell.

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

What are the three stop codons?

UAA, UAG, UGA

Step 1 of DNA Replication

Uncoiling of the parent DNA molecule

Step 2 of DNA Replication

Unzipping the hydrogen bonds between the base pairs

In RNA, which nitrogenous base pairs with adenine?

Uracil

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

Uracil

The native or _________ type strain exhibits nonmutated characteristics.

Wild

Which pentose sugar is found in DNA?

deoxyribose

Herpesvirus

dsDNA

Which of the following is not part of the lac operon?

lacI

The lac repressor binds to what site whithin the lac operon?

lacO

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

mRNA

Transcribed versoin of a structural gene or genes in DNA

mRNA

Which molecule contains the codons for the polypeptide?

mRNA

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

What are the three type of RNA?

mRNA, tRNA, rRNA

Which of the following are directly needed in order for translation?

mRNA, tRNA, rRNA, Amino Acids

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

rRNA

Which type of RNA comprises ribosomal subunits?

rRNA

Poliovirus

ssRNA virus

Brings the amino acids to the ribosome.

tRNA

Contains the anticodon and an amino acid site

tRNA

RNA polymerase binds to the __________ region to initiate transcription.

to bring amino acids to the ribosomes

The lactose operonis composed of the regulator, the __________ locus, and the structural locus.

Control

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

Correction of ultraviolet radiation mutations.

Protein synthesis takes place in the __________ of eukaryotic cells.

Cytoplasm

Transcription occurs in the _____________ of bacteria and ____________ of yeast cells.

Cytoplasm; nucleus

Eukaryotic chromosomes are composed of?

DNA

Genes are made up of __________, a marcomolecule made up of nucleotides.

DNA

Genes are made up of _____________, a marcomolecule

DNA

Genes are made up of what?

DNA

Which of the following best describes transcription?

DNA > RNA

RNA primers are removed by the action of the enzyme

DNA Polymerase I

Nucleotides are the building blocks of?

DNA and RNA

In eukaryotic cell, gene expression is regulated in response to ________________ stimuli such as nutrient and toxin levels, and also during growth and ________________.

Environmental and development

Proteins that remove incorrect bases and replace them with correct ones are termed _________ repair enzymes.

Excision

Are DNA sequences which encode for functional proteins.

Exons

Conjugation in gram-negative cells is directed by a plasmid called ________ 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 located in the cytoplasm?

F+

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

F-

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 foud on tRNA, and anticodons are found on mRNA

False

DNA pol II can initiate DNA synthesis.

False

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

False

A __________ is a sequence of DNA nucleotides that codes for one functional protein or RNA.

Gene

A __________ is a sequence of DNA nucleotides that codes for one functional protein or RNA?

Gene

Mutations that involve the addition, deletion, or substitution of no more than a few bases are referred to as.

Gene mutations

random fragments of disintegrating host DNA are picked up by the phage during assembly; any gene can be transmitted this way

Generalized transduction

Is the study of the inheritance of living things?

Genetics

The science of heredity is?

Genetics

The complete set of chromosomes and genes in a organism is referred to as the?

Genome

The enzyme _______ unzips the DNA helix prior to the start of replication.

Helicase

The enzyme _________ unzips the DNA helix prior to the start of replication.

Helicase

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

Helicase

Order of enzymes in which they participate in DNA replication

Helicase, Single-strand binding proteins,Primase, DNA Polymerase I

An ______________ operon, such as the lac operon, is usually in the "off" position, but can be turned on when the appropriate substrate is present.

Inducible

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

Inducible Operon

What 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

What is the inducer of the lactose operon?

Lactose

The newly forming DNA strand that is discontinously replicated in segments is called the?

Lagging strand

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

Leading

Which strand is replicated continuously without segments during DNA replication?

Leading

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

Ligase

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

Ligase

Which mutation changes an amino acid producing codon into a a stop codon?

Nonsense

The basic unit of DNA structure is?

Nucleotide

What is the basic unit of DNA structure?

Nucleotide

In protozoal or fungal cells, chromosomes are located in the?

Nucleus

Protein synthesis takes place in the ________ of eukaryotic cells.

Nucleus

In protein synthesis, eukaryotic and prokaryotic cells show similarities in all of the following EXCEPT the

Number of proteins encoded on a single mRNA and use of formyl-methionine as the first amino acid.

In replication of DNA, the lagging strand is replicated in a disontinuous manner forming?

Okazaki Fragments

Which of the following is required to replicate the lagging strand of DNA?

Okazaki fragments, primase, DNA ligase

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 enzyme synthesizes primer sequences during replication initiation?

Primase

Which type of organisms have their DNA arranged into operons?

Prokaryotes

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

Promoter

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

Promoter

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

Promoter region

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

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

Protein encodes RNA which encodes DNA.

Which organic molecule is formed from chains of amino acids?

Proteins

Operons often contain genes encoding proteins of one metabolic pathway

Repressible

The __________ protein is capable of repressing an operon.

Repressor

HIV

Retrovirus

Retroviruses, such as the HIV virus, carry their genetic information as RNA and convert it to DNA using the enzyme?

Reverse transcriptase

The pentose surgar found in RNA?

Ribose

Two subunits of the ________ comprise the site of protein synthesis.

Ribosomes

Translation of a mRNA sequence into a protein is terminated when the ribosome reaches a __________ codon.

STOP

Mutant bacteria may be detected by utilizing?

Selective media, replica plating, differential media

During __________ DNA replication, the newly made double helices are composed of one parent template and one newly synthesize strand.

Semiconservative

The termination of transcription involves?

Separation of RNA from the DNA template

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

Terminator

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

Terminator sequence

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

The chain of amino acids bound by peptide bonds.

The site on a chromosome where DNA replication begins is called?

The origin of replication

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

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

Triplet