Bacterial Genetics (Exam 1) Flashcards by Elizabeth Dower

How do bacteria multiply

binary fission

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What is the product of binary fission

identical daughter cells of parent cell

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What are the 3 main mechanisms through which bacteria will acquire new DNA

transformation
transduction
conjugation

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What is transformation

DNA acquired from the environment

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What is transduction

DNA acquired from bacteriophage

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What is conjugation

DNA acquired from bacterial “sex”

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What are the 3 types of DNA in a bacterial cell

bacterial chromosome
Plasmid
Bacteriophage

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What is bacterial chromosome

single piece of circular DNA, essential and non-essential genes

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What is plasmid DNA

small DNA circles, replicated independently of chromosome

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What is bacteriophage DNA

stable pieces of bacteriophage DNA present in bacterial cell

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Where are all of the essential genes in a bacteria found

chromosomal DNA

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What occurs in transformation

cells pick up DNA from the environment

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What occurs in transduction

phage injects DNA into bacteria

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What occurs in conjugation

donor cell produces a conjugation pilus and attaches to a recipient cell to which it then transfers a copy of its plasmid

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What occurs in transposition

transposon inserts itself into DNA

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How can you prevent transformation

digest the DNA with nucleases outside the cell

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How can you prevent transduction

kill the virus, disrupt DNA using heat, toxic environment

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How can you prevent conjugation

stop formation of sex pilus, separate the bacteria

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What is homologous recombination

swapping of chromosome parts between homologous pairs

imported DNA on linear pieces

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What is required for homologous recombination to occur

DNA is homologous

recA (recombinase A enzyme)

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What is site-specific recombination

Insert of a DNA strand that has no homology except for one site: the insertion site

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What are the major roles of site-specific recombination

integration of fertility factor or temperate phage

movement and insertion of transposons

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WHat type of DNA is taken up in transformation

naked DNA from environment by competent cells

usually linear

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What are the two ways in which a new gene can be stabilized

insertion: virus
Recombination: recA and homology needed

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What is transduction

transfer of bacterial DNA via bacteriphage

What is a bacteriophage

virus that attacks bacterial cells

What are the components of bacteriophage structure

filamentous, spherical or complex has a capsid (head), long tail that acts as a syringe

What type of information can be transmitted by a bacteriophage

DNA RNA | SS DS

How are generalized genes shared in transduction

phage picks up piece of bacterial DNA lytic virus

In generalize transduction which genes are more likely to be picked up

all genes have an equal chance of being transduced

How are specialized genes shared in transduction

dependent on integration of phage DNA into bacterial chromosome at specific site lysogenic virus

What type of error can occur in specialized transduction

excision error

What is an excision error

bacterial DNA to be excised and packaged with phage DNA

What type of genes will be transduced by lytic viruses

generalized

What type of genes will be transduced by lysogenic viruses

specialized

What are the two diffferent cycles in bacteriophage replication

lytic cycle | lysogenic cycle

What occurs during lytic cycle

lyses bacteria

What occurs during lysogenic cycle

integrates into bacterial genome

How will a lytic bacteriophage affect bacteria

takes over and makes new virus then kills the cell

How will a lysogenic bacteriophage affect bacteria

site specific recombination, everytime cell replicated it will make new virus too

What is a virulent phage

a phage that reproduces only by a lytic cycle

What is a temperate phage

bacteriophage that chooses between lytic and lysogenic pathway of development

How will a temperate phage exhibit lysogeny

``` integration into host chromosome forming a po-phage expression of phage genes is repressed no new phage are made host cell survives phage dna replicates as part of host ```

What processess are homologous recombination necessary for

transduction | transformation

What type of cycle will virulent viruses undergo and what type of tranduction is this

lytic cycle | generalized transduction

What will be produced as a result of lytic infection

production of viruses and their release upon cell lysis

WHat type of bacteria will have a pro-phage

lysogenic bacteria

What is lysogenic conversion

acquisition of bacterial properties due to pro-phage

What is the first step to specialized transduction

lysogenic conversion

How can a pro-phage be destabilized

UV light, chemicals

When will induction occur

if repressor is damaged by UV, cold, or alkylating agents. Prophage is excised and cell goes into lytic replication

What may result from an excision error

viral DNA will get cut up due to no homology. If homology and RecA homologous recombination will occur for bacterial DNA

What is required for conjugation

male and female bacterial sex pilus

What will occur if you mix F+ cells with F- cells

F- cells rapidly become F+

What are conjugative plasmids

genes that promote their own transfer

What is conjugation

transfer of genes from one cell to another by cell to cell contact

What type of donor cells will have fertility plasmids

male

What will fertility plasmids code for

sex pili genes that stabilize mating bacteria genes which direct conjugal DNA transfer and other genes

What is oriT

ss break in DNA and oriT begins the transfer of one strand of DNA

What is an insertion sequence

where a plasmid can insert itself into the bacterial chromosome

Where are the insertion sequence and oriT located

right across from each other on the plasmid

What are female cells

recipient cells that lack fertility factors and genes

What does it mean if a cell has a high frequency of recombinase

wants to share with everything

Where is the oriT in a cell with a high frequency of recombinase

right in the middle

What makes a cell an Hfr cell

strains of bacteria with F plasmid integrated are Hfr

What is the process of sharing everything due to Hfr

chromosomal mobilization

How does F plasmid have the ability to transfer itself to other cells

integrates itself into the chromosome

How does transfer of a chromosome to recipient cells occur

sequential manner

Does a donor cell lose the DNA it transfers

no it made a copy

What is a transposon

mobile genetic element that can move between plasmids and chromosomes

What is an example of intrinsic antibiotic resistence

cell lacking cell wall is resistant to penicillin

What is an example of chromosomal mechanisms of antibiotic resistance

modification of receptor for drug (PBP)

How can plasmids play a role in antibiotic resistance

R factors carry genes for drug resistance often code for enzymes that modify drug

What are possible uses of phage therapy

target antibiotic resistant bacteria