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