Chapter 9 - An Introduction to Microbial Genetics

A DNA triplet encodes _____ codon(s) and _____ amino acid(s).

1 1

Transduction occurs through what?

A bacteriophage

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

Base

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

nonsense

What type of RNA composes ribosomal subunits?

rRNA

What type of RNA forms part of the ribosome?

rRNA

The RNA type that transfers amino acids to the growing peptide chain in translation is _____.

tRNA

_____ bring the amino acids to the ribosome.

tRNA

DNA polymerase III is responsible for what?

Building the DNA chain

What are DNA polymerases responsible for?

Building the DNA chain Proofreading/repair

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

Carbons in the deoxyribose sugar

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

Chromosome

Before a bacterial cell can undergo binary fission, the _____ must be duplicated.

Chromosome

A(n) _____ is a specific sequence of 3 mRNA nucleotides that encodes a particular amino acid.

Codon

Each mRNA _____ codes for a particular amino acid which is then bonded with other amino acids during translation to form a protein.

Codon

The central dogma hypothesis of genetics states that _____ encodes _____ which encodes protein.

DNA RNA

What determines the order of amino acids in the primary structure of a protein?

DNA sequence of a gene

The pentose sugar found in DNA is _____.

Deoxyribose

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

Deoxyribose sugar

What are the parts of a nucleotide in DNA?

Deoxyribose sugar Phosphate Nitrogenous base

What DNA sequences encode functional proteins?

Exons

True or False?: A point mutation results from an insertion or deletion of nucleotides, and always leads to a shirt of the triplet sequence from the point of mutation downstream.

False

True or False?: DNA polymerase converts DNA into the various types of RNA during transcription.

False

What occurs during posttranslational modification?

Formyl methionine (f-Met) is removed Proteins join with other proteins to form quaternary structures A tertiary protein conformation forms Cofactors are added to proteins destined to be enzymes

_____ mutations are generally most harmful to cells because they cause the greatest change in the amino acid sequence of a protein.

Frameshift

Plasmids are found in what types of organisms?

Fungi Bacteria

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

Gene

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

Genes

The science of heredity is _____.

Genetics

What term represents all of the genetic information within a cell?

Genome

The entire genetic makeup of an organism is its _____, but the expression of certain genetic traits are known as its _____.

Genotype Phenotype

Adenine and _____ are purines found in DNA.

Guanine

The purine _____ pairs with the pyrimidine cytosine.

Guanine

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

Helicase

Genetic inheritance in microorganisms is best defined by what term?

Heredity

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

III I

What type of DNA mutation occurs as a consequence of exposure to chemical or physical mutagens?

Induced

Lactose acts as an _____ in the lactose operon.

Inducer

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

Inducible operon

What is the order of events in transcription?

Initiation Elongation Termination

What is the order of events in translation?

Initiation Elongation Termination

_____ are DNA sequences that do not encode protein, but have a regulatory function.

Introns

What strand is replicated discontinuously in segments during DNA replication?

Lagging

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

Ligase

What type of mutation results in a different amino acid being incorporated into a protein?

Missense

The genome of prokaryotic or eukaryotic cell includes DNA found in what sites?

Mitochondria Chloroplasts Chromosomes Plasmids

A chemical or physical agent that induces a change in DNA is referred to as a _____.

Mutagen

What defines a chemical or physical agent that induces a change in DNA?

Mutagen

What is an agent that induces changes in DNA?

Mutagen

An organism that has a mutation is called a _____.

Mutant

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

Mutation

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

Mutations

A "stop" codon in mRNA is also known as a _____ codon.

Nonsense

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

Nonsense

What is the basic unit of DNA structure?

Nucleotide

In replication of DNA, the lagging strand is replicated in a discontinuous manner forming _____ fragments.

Okazaki

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

Oncogenic

The _____ section of the control locus acts as an on/off switch for transcription.

Operator

Gene expression in prokaryotes is regulated through _____.

Operons

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

Phenotype

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

Mutations that involve the addition, deletion, or substitution of a single base are referred to as _____ mutations.

Point

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 the DNA _____ I and III.

Polymerase

Gram-positive cells conjugate and transfer genetic material through which structure?

Pore in cell wall

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

Primary

During replication initiation, the enzyme _____ synthesizes primer sequences.

Primase

What enzyme synthesizes primer sequences during replication initiation?

Primase

What type of organisms have their DNA arranged into operons?

Prokaryotes

RNA polymerase bind so the _____ region to initiate transcription.

Promoter

During protein synthesis, many copies of a specific _____ can be synthesized from a single _____ transcript.

Protein mRNA

The DNA blueprint specifics how to make what type of macromolecule?

Proteins

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

Proteins

How does RNA differ from DNA in bacteria and eukaryotes?

RNA is single-stranded In RNA, uracil replaces thymine

What is the large enzyme complex involved in synthesizing RNA from a DNA template?

RNA polymerase

The initiation of transcription occurs when _____ _____ recognizes and binds to a region of DNA called the _____ region.

RNA polymerase Promoter

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

Replication

The _____ protein is capable of repressing an operon.

Repressor

The ______ protein is capable of repressing an operon.

Repressor

The protein product of a repressor gene is the _____ which binds the operator to stop protein synthesis.

Repressor

The protein product of a repressor gene is the _____ which binds to the operator to stop protein synthesis.

Repressor

The enzyme _____ _____ synthesizes a single strand DNA from the viral RNA template.

Reverse transcriptase

What pentose sugar is found in RNA?

Ribose

What are the functions of RNA polymerase?

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

The complementary sequence of 5'-AAGTC-3' is 3'-_____-5'.

TTCAG

The _____ (contemplate/template) strand of DNA contains the order of nucleotides that are transcribed into RNA

Template

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

Terminator

What did Griffith's experiment using Streptococcus pneumoniae demonstrate?

That 2 different strains of S. pneumonia transformed into a third unique strain

During _____ mRNA is converted into a protein.

Translation

The ribosome, composed of rRNA and protein, is involved in the process of _____.

Translation

The term _____, or codon, is a sequence of 3 nucleotides in mRNA that encodes an amino acid.

Triplet

True or False?: Proteins contribute to the phenotype of an organism.

True

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

True

True or False?: 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

True or False?: 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

_____, _____, and _____ are the three stop codons within the genetic code.

UAA UAG UGA

The nitrogenous base thymine is only found in DNA, while _____ is only found in RNA.

Uracil

What nitrogenous base is unique to RNA molecules?

Uracil

The native or _____ type strain describes cells that carry non mutated DNA.

Wild

The DNA of a chromosome is _____-stranded.

double

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

genotype

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

mRNA

_____ contains the codons for the polypeptide.

mRNA

What are the three types of RNA?

mRNA tRNA rRNA

How many replication forks are formed form opening a section of the parental DNA molecule during replication?

2

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

3'

The strand of mRNA is constructed in the _____ to _____ direction.

5' 3'

What is the main effect of ultraviolet radiation on DNA?

Abnormal bonding between adjacent pyrimidines

Transcription elongation involves...

Adding of nucleotides to the growing mRNA chain.

The purine nitrogenous bases found in RNA are guanine and _____.

Adenine

Which nitrogenous bases are found in DNA?

Adenine Cytosine Guanine Thymine

Nucleotide is to nucleic acid as _____ _____ is to protein.

Amino acid

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

Anticodon

In DNA the 2 strands of the helix are arranged in _____ orientation.

Antiparallel

A bacterial cell described as _____ can accept soluble DNA from the surrounding environment.

Competent

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

Conjugation

During which method of gene transfer are bacterial cells in direct contact?

Conjugation

_____ in bacteria refers to horizontal gene exchange via pili.

Conjugation

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

Corepressor

Protein synthesis takes place in the _____ of bacterial cells.

Cytoplasm

The purine guanine pairs with the pyrimidine _____.

Cytosine

What term refers to the transfer of genes between donor and recipient microorganisms?

Recombination

_____ refers to the transfer of genes between donor and recipient microorganisms.

Recombination

The _____ of the genetic code results in several codons encoding the same amino acid.

Redundancy

The _____ is the gene that codes for a protein capable of repressing the operon

Regulator

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

The termination of transcription involves what?

Separation of RNA from the DNA template

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

Spontaneous mutation

The _____ codon AUG of mRNA is associated with the tRNA anticodon UAC and the amino acid methionine.

Start

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

Stop

What kind of gene encodes a specific functional protein?

Structural

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

Structural genes Operator Promotor

What are the parts of the lactose operon?

Structural locus Regulator Control locus

_____ is the process of decoding DNA into messenger RNA.

Transcription

What are the two steps of protein synthesis?

Transcription Translation

One reason protein synthesis is more efficient in bacteria than in eukaryotes because bacterial _____ and _____ are simultaneous.

Transcription Translation

What recombination method involves the transfer of DNA via bacteriophages?

Transduction

During the process of _____ a competent bacterial cell may accept soluble DNA from the surrounding environment.

Transformation

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

Transformation

A _____ serves as the vector for transduction in bacteria.

bacteriophage