EXAM 3 P5

Question 1

exchange of bacterial genetic information

Answer 1

new genes can be acquired during their lifetime, usually only small amounts of DNA not whole genomes

Question 2

plasmids

Answer 2

pieces of DNA (extrachromosomal genetic elements) and generally circular
smaller than the chromosome
have their own origin of replication using the cells normal DNA replication machinery
often called multi copy plasmids since there are multiple per cell
not essential for cell survival

Question 3

plasmid function

Answer 3

provide the cell with something positive by expanding metabolic ability
can express conjugation, provide metabolic function, antibiotic production, resistance, and virulence
essential tools in all molecular biology labs

Question 4

homologous recombination

Answer 4

new DNA that comes in is a plasma with its own origin of replication and can replicate past the progeny cells
if the DNA lacks an origin, and is not passed on to part of the genome, it must find another way
recombination requires 2 molecules have an extended region of sequence similarity

Question 5

recA proteins

Answer 5

bind ssDNA and initiates the process of homologous recombination
takes the ssDNA and scans across the other dsDNA and finds homologous regions, aligns them, and initiates recombination

Question 6

horizontal gene transfer

Answer 6

transfer from one unrelated cell to another

conjugation, transformation, and transduction

Question 7

vertical gene transfer

Answer 7

gene transfer to your progeny

Question 8

donor cell/strain

Answer 8

origin of the DNA to be transferred

Question 9

recipient cell/strain

Answer 9

cell receiving the new DNA

Question 10

recombinant cell/strain

Answer 10

result if the stability maintains the incoming DNA

about 99% recipient, only a small bit is transferred

Question 11

DNase

Answer 11

an enzyme that destroys DNA

Question 12

Griffith

Answer 12

discover the transforming principle in the 1920s
did experiments looking at the ability of streptococcus to cause disease in mice
type 1 was smooth and 2 was rough. if 1 was injected into the mice, they died. 1 had a “smooth” capsule material. if he took 1 and killed the capsule, the mice lived. if 2 were injected they lived. he combined both living factors for injection and the mice died. something in the dead smooth cells was transforming the rough cells into smooth cells.

Question 13

Avery, Macleod, and McCarty

Answer 13

in the 1940s, they purified DNA and showed the process Griffith performed was DNase sensitive
provided the first direct evidence that DNA is the genetic material

Question 14

competent

Answer 14

able to be transformed, they bind, uptake, and recombine DNA

Question 15

natural transformation

Answer 15

species can naturally become competent. they have a set of genes allowing them to find DNA in the environment, transfer it to the cell, and recombine it into their.
dsDNA is bound to a cell surface
easier to pick up ssDNA than dsDNA

Question 16

artificial (chemical) transformation

Answer 16

forces competence
no genes or cellular energy required
not an active process of the cells
dsDNA enters the cell
treats the cells with salts, detergents, chemicals, forming holes in the mem and disrupting it.
kill about 90% of the cells

Question 17

electroporation

Answer 17

suspends the cells in a solution and pasteur it with a high voltage of electric shock, depolarizing the mem, ridding it of negative charges so DNA can get through

Question 18

transduction

Answer 18

cell gets infected with a virus and while reproducing the virus accidentally packages some of the host cell DNA instead of the viral DNA. the products look and act like viruses, but carry non-viral DNA, which can get injected into a recipient cell

Question 19

lytic cycle

Answer 19

breaks down host DNA with its small bits, sometimes making mistakes

Question 20

phage lysate

Answer 20

contains many phage particles and some transducing particles

Question 21

transducing particle

Answer 21

can still bind another host cell and inject its DNA into the cell

Question 22

P22 phage

Answer 22

infects salmonella

Question 23

P1 phage

Answer 23

infects e. coli

Question 24

conjugation

Answer 24

DNA transfer from direct cell-cell contact
almost always encoded on a plasmid
requires an origin of transfer (ori T)
2 origins are on the plasmid
not DNase sensitive since DNA is never exposed to the environment

Question 25

tra genes

Answer 25

produce a set of tra proteins, which are the apparatus that allow the process of conjugation

Question 26

F+

Answer 26

potential donor

has a plasmid

Question 27

F-

Answer 27

potential recipient

Question 28

F pilus

Answer 28

pulls cells together during conjugation to form a mating pair

Question 29

chromosome mobilization

Answer 29

results from the formation of Hfr strains

Question 30

integrated F plasmid cell

Answer 30

still expressed tra gene, makes a pilus, and initiates DNA transfer at ori T

Question 31

recipient

Answer 31

can recombine homologous regions of incoming chromosomal DNA
never gets the whole F plasmid sequence
does not become F+