Ch. 8 Bacterial Genetics

The F or Fertility plasmid contains genes that are required for bacterial _________ a) transformation b) conjugation c) competence d) transduction

b) conjugation

Which is an agent that induces changes in DNA? a) mutation b) mutagen c) mutant

b) mutagen

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

competent

In E. coli about 75% of the genes are found in all strains. These conserved genes are called the ________ genome.

core

A base substitution that changes an amino acid-encoding codon to a stop codon is called a(n) ______________ mutation. a) missense b) frameshift c) deletion d) nonsense e) silent

d)

Selecting penicillin-resistant mutants by plating them on a medium containing penicillin is an example of ________ selection. a) degenerate b) indirect c) differential d) direct

d) direct

A(n) ________ mutation is a base substitution that changes the codon to one that specifies a different amino acid.

missense

An organism that has a mutation is called a _____________.

mutant

Low copy number

occur in one or a few copies per cell

In bacterial conjugation, F+ donor cells are high frequency recombinant (Hfr) cells when the F ______ is integrated into the chromosome

plasmid

A __________ mutation occurs if a single base pair is changed during DNA synthesis

point

A bacteriophage consists of a(n) _________ coat that surrounds the nucleic acid ___________

protein, genome

Mutation rates are low bc proofreading and _________ mechanisms fix altered or damaged DNA before it can be passed to progeny.

repair

Horizontal gene transfer

transfer of DNA from a source other than the parent organisms

Conjugation, DNA-mediated __________, and _____________ are methods of horizontal gene transfer in bacteria.

transformation, transduction

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

transposons

Which type of mutation alters the reading frame of a gene? a) missense b) frameshift c) reversion

b) frameshift

Recognition and repair of errors in nucleotide incorporation by DNA polymerase is called ______________. a) excision repair b) mismatch repair c) proofreading d) photoactivation

c)

Place the steps of F plasmid transfer in the correct order. a) one strand of F plasmid is cut in origin of transfer b) complement of transferred strand is synthesized c) F pilus makes contact with recipient cell d) single strand on F plasmid is transfered to the recipient cell

c) a) d) b)

_________ are circular pieces of bacterial DNA that do not usually encode information essential to the life of a cell.

Plasmids

Plasmids vs. Chromosomes Contains an origin of replication Made of double stranded DNA

Plasmids and Chromosomes

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

Reversion

Chemical mutagens can cause which of the following? a) frameshift mutations b) base substitutions c) double stranded breaks d) thymine dimers

a) b)

A(n) _____________ is a mutant that requires a growth factor. a) auxotroph b) autotroph c) heterotroph d) prototroph e) phototroph

a) auxotroph

RTF

encodes properties needed for conjugation

High copy number

occur in many copies in a cell

The ___________ of an organism is some characteristic that can be observed or measured.

phenotype

Which of the following can be transferred from one cell to another by conjugation? a) bacterial proteins b) plasmid DNA c) chromosomal DNA d) phage DNA e) bacterial DNA

b) plasmid DNA c) chromosomal DNA

Which of the following types of radiation are mutagenic? a) ultraviolet rays b) x-rays c) infrared rays

a) ultraviolet rays b) x-rays

An auxotroph can be isolated from a prototrophic parent strain by _________ selection. a) direct b) indirect c) degenerate d) differential

b) indirect

Errors by DNA polymerase that incorporate the wrong nucleotide into replicating DNA can be repaired quickly by which two mechanisms? a) excision repair b) mismatch repair c) SOS repair d) proofreading by DNA polymerase e) Photoactivation

b) mismatch repair d) proofreading by DNA polymerase

The process in which better adapted organisms reproduce at higher rates in a given environment is called: a) transduction b) natural selection c) transformation d) genetic recombination

b) natural selection

Place the steps of DNA-mediated transformation in the correct order. a) single-stranded DNA enters cell after one strand has been degraded b) single-stranded DNA integrates into genome after entering the cell c) double-stranded DNA molecule binds to surface receptor d) nucleases degrade one strand of double-stranded DNA at the cell surface

c) double-stranded DNA molecule binds to surface receptor d) nucleases degrade one strand of double-stranded DNA at the cell surface a) single-stranded DNA enters cell after one strand has been degraded b) single-stranded DNA integrates into genome after entering the cell

Bacteriophages can consist of: a) protein coat (capsid) b) nucleus c) DNA genome d) RNA genome e) hybrid DNA/RNA genome f) membrane (envelope)

a) protein coat (capsid) c) DNA genome d) RNA genome

The two types of transduction are: a) specialized b) filamentous c) generalized d) localized e) specific

a) specialized c) generalized

__________ are segments of DNA that can move from one location to another in a cell's genome a) transposons b) mutagens c) transcripts d) plasmids

a) transposons

Genetic change in bacteria occurs through which two mechanisms? a) mutation b) vertical gene transfer c) horizontal gene transfer

a) mutation b) horizontal gene transfer

Which of the following are sources of "naked" DNA? a) contained within bacteria that lack cell walls b) secreted into the environment by bacteria c) contained in bacteriophages d)lysed (burst) bacterial cells

b) secreted into the environment by bacteria d) lysed (burst) bacterial cells

R genes

encode resistance traits

Mutant cells in a bacterial culture can be identified by _______ and _______ selection methods.

direct, indirect

Vertical gene transfer

transfer of DNA from parent organisms during reproduction

Broad host range

Can replicate in many different species

Narrow host range

Can replicate in only one species

Plasmids vs. Chromosomes Cells cannot survive their loss Found in all eukaryotes and prokaryotes

Chromosomes

A point mutation always leads to a shift of the reading frame from the point of mutation downstream. True or False

False

Plasmids vs. Chromosomes Typically do not encode genes essential to the life of the cell Often the location of antibiotic resistance genes in bacteria

Plasmids

The consequences of not repairing damaged DNA in cells include a) cancer (in animals) b) cell death c) cells that have less mutations

a) cancer (in animals) b) cell death

It is important for people interested in human health to have a basic understanding of bacterial genetics bc it can help explain how: a) multi-drug resistant bacteria like MRSA arise b) bacteria acquire resistance traits c) effective penicillin is against most bacteria

a) multi-drug resistant bacteria like MRSA arise b) bacteria acquire resistance traits

Which mechanism of gene transfer involves the uptake of "naked" DNA by competent bacterial recipient cells? a) transduction b) transposition c) conjugation d) transformation

d) transformation

Bacteria are a great experimental system for genetic studies because when they can accumulate to very high number in small volumes: a) the genetic makeup of the population is very stable and never mutates b) the bacteria divide indefinitely so the population number remains constant c) rare genetic changes that happen can be easily studied

c) rare genetic changes that happen can be easily studied