Microbiology (Human Pathogens) Chapter 8 Delgado

Errors by DNA polymerase that incorporates the wrong nucleotide into replicating DNA can be repaired quickly by which two mechanism

- Mismatch repair - Proofreading by DNA polymerase

place the steps of F plasmid transfer in the correct order

1)F pilus makes contact with recipient cell 2)one strand of F plasmid is cut in origin of transfer 3) single strand of the F plasmid is transferred to the recipient cell 4) complement of transferred strand is synthesized

Conjugation

A temporary union of two organisms for the purpose of DNA transfer.

________Such as E.Coli are an excellent model system for genetics studies because they can quickly grow to high densities, allowing us to screen for rare genetic events

Bacteria

chemical mutagens can cause 2 types of mutations: ________ substitution and ___________ mutations .

Base Frameshift

Bacteriophages can consist of

DNA genome RNA genome protein coat (capsid)

non-homologous recombination

DNA recombination that does not require extensive nucleotide sequence similarity in the stretches that recombine

In humans 2 of the genes associated with the development breast cancer encode enzymes involved in ___________

DNA repair

horizontal gene transfer

DNA transfer from one bacterium to another by conjugation, DNA-mediated transformation, or transduction

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

False

Barbara McClintock (1902-1992)

Observed that kernel colors in corn not inherited in a predictable manner • Concluded segments of DNA moved in and out of genes involved in color • Destroyed function of genes • Published results in 1950 • Met with skepticism • DNA believed stable • Idea established by 1970s • Awarded Nobel Prize in 1983 • Termed transposons • "Jumping genes"

A mutant that requires a growth factor is a

auxotroph

cells that have the ability to take up DNA from the environment are called ___________ cells

competent

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

conjugation

which of the following mutations frequently results in the production of a shortened and non functional protein because a different set of codons is translated.

frameshift

which type of mutation alters the reading of a gene

frameshift

The 2 types of transduction are

generalized specialized

Which of the following terms describes the sequence of nucleotides (genetic makeup) of an organism or a cell?

genotype

Transduction

mechanism of horizontal gene transfer in which bacterial DNA is transferred inside a phage coat

DNA-mediated transformation

mechanism of horizontal gene transfer in which the bacterial DNA is transferred as "naked" DNA

A _________ is an agent that that induces changes in DNA

mutagen

an organism that has a mutation is called _______

mutant

A ________ is a change in DNA that is passed on to daughter cells.

mutation

_______is the process of by which organism better adapted to an environment reproduce at a higher rate

natural selection

A ________mutation is a base substitution that changes an amino acid encoding codon to a stop codon.

nonsense

homologous recombination

process by which a cell replaces a stretch of DNA with a segment that has a similar nucleotide sequence

Bacteria are great model systems for genetic studies because when they are grown to very high numbers in small volumes of simple media _________.

rare genetic changes that happen can be easily studied

consider a population of bacteria susceptible to an antimicrobial. If a bacterium acquires a spontaneous mutation that gives resistance to the antimicrobial, this bacterium will __________if the population is exposed to the antimicrobial.

grow without competition

mutation rates are low because proofreading and ______ mechanisms fix altered or damaged DNA before it can be passed to the progeny.

repair

The return of a gene from a mutated state to its original, non-mutated state is called a

reversion

Transposon

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

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

silent

Random genetic changes that result from normal cellular processes are

spontaneous mutations

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

substitution

Phenotype

the observed characteristics of a cell

DNA mediated___________ involves the uptake of 'naked' DNA by competent bacterial recipient cells.

transformation

which of the following are methods of gene transfer in bacteria

transformation transduction conjugation.

The native or wild type strain describes the typical phenotype of strains isolated from nature .

true

Which of the following types of radiation are mutagenic

ultraviolet rays x-rays

If a scientist is working with bacteria that have the typical phenotype of those isolated from nature, the bacteria are considered to be _____ type

wild

Plasmid

A DNA molecule that replicates independently pf a chromosome.

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

Transposon

Mutation

a change in the nucleotide sequence of a cell's DNA that is passed on to daughter cells

prototroph

a microorganism that does not require any organic growth factors

Auxotroph

a microorganism that requires an organic growth factor

mutant cells in bacterial cultures can be isolated by _____________ and ____________ selection methods

direct indirect

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

false

bacterial conjugation does not require contact between the 2 cells

false

Genotype

the sequence of nucleotides in an organism's DNA