Microbiology Chapter 8

A ____ is a virus that infects bacteria

Bacteriophage

In generalized transduction, a ____ transfers DNA from one bacterial cell to another

Bacteriophage

_____ are molecules whose structure resembles that of nucleobases and can be mistakenly incorporated into DNA

Base analogs

Bacteriophages consist of

DNA genome, protein coat, RNA genome

When excision errors produce plasmids containing both chromosomal and F plasmid DNA, the resulting plasmid is called an ____ plasmid

F prime

T/F: plasmids are insertion sequences that can lead to changes in genotype within a cell or between cells

False

T/F: Ultraviolet rays are chemical mutagens

False: UV rays are a form of radiation that is commonly used to induce mutations

A ______ mutation results from an insertion or deletion of nucleotides, leading to a shift of the reading frame from the point of mutation downstream

Frameshift

In bacterial conjugation, F+ donor cells are high frequency recombinant ____ cells when the F _____ is integrated into the chromosome

Hfr, plasmid

The distortion of DNA by thymine dimers directly blocks which of the following cellular processes?

Replication and transcription

Chemical mutagens can cause what?

-Base substitutions -Frameshift mutations

Genes into which transposons "jump" are usually ______ by the event

inactivated

Mutations that are caused by external influences such as radiation or chemicals are called ____ mutations

induced

The genes that vary considerably among strains of a species are called the

mobile gene pool

A ______ is an agent that induces changes in DNA

mutagen

_____ recombination is the process by which a cell replaces a portion of its DNA with a segment that has no extensive similarity in nucleotide sequence

non-homologous

A _____ mutation is a base substitution that changes an amino acid encoding codon to a stop codon

nonsense

Chemical mutagens that modify _____ increase the odds of incorrect nucleotide incorporation during DNA replication

nucleobases

Genomic islands that encode disease-causing factors such as exotoxins, capsules, and adherence factors are called _____ islands

pathogenicity

Donor and recipient bacterial cells are connected by a sex ____ during conjugation

pilus

Small, usually circular pieces of DNA that contain their own origin of replication are called

plasmids

A _____ mutation involves any substitution of a single nucleotide that does not change the DNA reading frame

point

An organism that does not require growth factors is called a

prototroph

UV radiation causes a very specific type of DNA damage called

thymine dimers

Most transposons contain _____ terminators

transcriptional

The bacteria Agrobacterium tumefaciens transfers tumor-causing genes to a variety of plants using the ______

Ti Plasmid

Chemicals that modify nucleobases alter the ______ properties of a nucleobase

base-pairing

The F or Fertility plasmid contains genes that are required for bacterial ______

conjugation

The genes that are present in all strains of a given species are called the

core genome

A bacterial cell described as _____ can take up DNA from the surrounding environment

competent

____ mutations are generally the most harmful to cells because they change all of the codons downstream of the mutation

Frameshift

Ultraviolet radiation causes covalent bonds to specifically form between adjacent ____ molecules on a DNA molecule

thymine

State if chromosomes/plasmids/both: -Found in all prokaryotes and eukaryotes -Location of antibiotic resistance genes in bacteria -Contains an origin of replication -Made of double stranded DNA -Cells cannot survive their loss -Typically do not encode genes essential to the life of the cell

-Chromosomes -Plasmids -Plasmids and chromosomes -Plasmids and chromosomes -chromosomes -plasmids

X rays can cause which types of damage to a DNA molecule?

-Nucleobase alterations -Single stranded breaks -Double stranded breaks

Place the steps of DNA-mediated transformation into the correct order:

1. Double-stranded DNA molecule binds to surface receptor 2. Nucleases degrade one strand of double-stranded DNA 3. Single-stranded DNA enters cell 4. Single-stranded DNA integrates into genome

Place the steps of F plasmid transfer in the correct order

1. F pilus makes contact with donor cell 2. One strand of F plasmid is cut in origin of transfer 3. Single strand of F plasmid is transferred to the recipient cell 4. Complement of transferred strand is synthesized

Genomic island

A large segment of a cell's genome that has clearly originated in a different species

Sources of naked DNA

Lysed bacterial cells, secreted into the environment by bacteria

a base substitution that changes the codon to one that specifies a different amino acid

Missense mutation

Which of the following are possible outcomes of a base substitution?

Missense mutation, nonsense mutation, and silent mutation

Free DNA found in the environment is called ____ DNA

Naked

Which odds are not within the range of mutation rates for a typical gene?

One in one thousand, one in one hundred, and one in ten trillion

Components of the simplest transposon, an insertion sequence?

Transposase gene and inverted repeats

DNA segments that increase the rate of mutations by inserting themselves into a gene and inactivating it

Transposons

Sequences of DNA that can move to new positions within the genome of a single cell are called

Transposons

_____ are segments of DNA that can move from one location to another in a cell's genome

Transposons

Base ____ structurally resemble nucelobases and can be mistakenly incorporated into nucelotides and then into DNA

analogs

A likely consequence of a _____ mutation is the appearance of an early stop codon that produces a shortened and thus non-functional protein

frameshift

Not a possible outcome of a base substitution?

frameshift mutation

Chemical mutagens that squeeze between base pairs and induce frameshift mutations are called

intercalating agents

____ agents increase the rate of _____ mutations by inserting themselves between adjacent base pairs in a DNA strand

intercalating, frameshift

The origin of "naked" DNA in the environment is from cells that have ____ or from living cells that actively ____ the DNA into the environment

lysed, secreted

A base substitution that results in a codon that still codes for the wild type amino acid is called a ____ mutation

silent

random genetic changes that result from normal cellular processes

spontaneous mutations

Base ____ mutations occur when an incorrect nucleotide is incorporated in place of another during DNA synthesis

substitution

The most common type of mutation is the base ____ mutation, where an incorrect nucleotide is incorporated during DNA replication

substitution

F' plasmid

when integrated F plasmid DNA is excised from the chromosome, an excision error can remove chromosomal DNA along with the F plasmid DNA, creating this type of plasmid

____ radiation can caused single and double stranded breaks in a DNA strand and nucleobase alterations

x-ray

Types of radiation that are mutagenic

x-rays and ultraviolet rays

_____ is the change of a mutated genetic sequence back to its original, non-mutated form

Reversion