Ch. 11 Genetics

minimal media

contains only an organic carbon source and a variety of inorganic ions

prototroph

bacteria is wild type for all growth requirements

completed media

contains particular compounds bacteria can not produce

auxotroph

bacteria is lacking in a particular growth requirements

bacteria growth is like

asexual reproduction

lag phase

initial growth rate very slow, generation of metabolites

log phase

exponentially growing cells, fixed interval between doublings

stationary phase

cells stop dividing, depletion of oxygen and nutrients

why do bacteria differ in their growth requirements

bacteria undergo spontaneous mutations taht cause them to gain or loss the function of particular genes

what does it mean that bacteria are haploids

that all mutations will be expressed in the descendants of the mutant

what is the penicillin MOA effective against

only Gram positive bacteria

how is the penicillin MOA effective

it interferes final assembly of the cell wall and results in cell death

what have mutations results in

modifications of various cellular targets/enzymes

what are some changes that mutations can cause

change in binding affinity to PBPs; production on enzymes that inactivate penicillin; autolytic enzymes are not activated by penicillin; deficiency or inaccessibility of PBP’s

what do bacteria no make

gametes

how is bacteria transferred

from one bug to another

what sort of direction is bacterial DNA transfer

unidirectional

when is the only time that DNA that has been received by recipient is replicated and inhertied

unless it is first recombined with recipient c-some

conjugation

passing of extra chromosomal DNA (plasmid)

transformation

picking up foreign DNA from environment

transduction

phages (bacterial viruses) transfer DNA into the host bacteria

what is conjugation similar to

sexual reproduction

what is created between two bacterias during conjugation

conjugation bridge

what is the conjugation bridge used for

DNA from one bacteria moves across bridge to other bacteria

what is F factor

is a mobile element that is passed to all recipient cells

even though conjugation is a rare event what can cause it to result in bacterial antibiotic resistance

selection pressure

high-frequency recombination

recombination is 1000 times more frequent than the parental strain

what is the difference between Hfr and F+ cells

in Hfr the recipient F - cell never become the F + cell

what is F factor integrated into

the parental chromosome

how can you determine the gene sequence

by overlaying many different strains

what is transferred first

genes adjacent to origin

what is transferred last

F factor

why is transformation important to genetics

was used to show that DNA is the genetic material; can be used for determining gene order, linkage, and distance; allows for expression and selection of particular genes which helps to determine gene regulation/function

engineered transformation

bacterial have been altered to take up extracellular DNA and incorporate it into its own chromosome

natural transformation

bacteria is naturally able to take up extracellular DNA and incorporate it into its own chromosome

in engineer transformation what are plasmids used for

to transfer specific DNA sequences to bacteria

what are the steps of cut and paste DNA

digest DNA with restriction endonuclease; purify and ligate in plasmid; and transform bacteria and select

what is step one of the transformation process

entry of DNA into cell

what is step two in the transformation process

recombination of DNA into recipients chromosome

what is required to incorporate the transforming DNA

two crossovers

if two genes are far apart on donor DNA where will they be found

on different DNA fragments

co-tranformation

probability of simultaneous transfer would be equal to product of probabilities

what is the probability if two genes are located very close together

it would be close to the probability of a single-gene transfer

what do bacteriophages function as

intermediaries in the transfer of genetic material from one bacteria to another

what is the importance of transduction to genetics

establishes gene linkage and mapping of bacterial chromosomes

once a phage bind what does it do

inject their DNA into the host bacterial cell

what happens once the phage DNA is replicated

the host cell DNA is chopped up

instead of integrating and picking up small fragments of phage DNA what does the phage progency pick up

fragments of the cells DNA

what are the barriers to horizontal gene transfer

CRISPR and restriction endonucleases