Genetics Ch. 7

lederberg, tatum

1946 - discovered genetic transfer in bacteria (2)

conjugation, transduction, transformation

3 types of horizontal gene transfer

Pilus

A tube that allows bacteria to transfer genetic material during conjugation.

proteins, F-factor, membrane

At the start of conjugation, the exporter a complex of 10-15 _____________ encoded by the __________ that span both inner and outer ____________, pumps the DNA Relaxase complex into the recipient cell

artificial transformation

DNA uptake occurs w/ the help of lab equipment

natural transformation

DNA uptake occurs w/out outside help

u-tube

Davis used a ____________ apparatus -- filter w/ pores large enough to allow genetic material, but block bacterial cells

plasmid

F+ ______ has its own origin of replication, exists as a single copy separate from chromosome

within, between

HGT can occur _____ and ______ species

acquired antibiotic resistance

HGT has dramatically contributed to the phenomenon of...

high frequency of recombination

Hfr stands for

F+

Hfr strains derives from ___ strains

F factor

In E. coli, strains contain a small circular piece of DNA termed ____________ plasmid (+: with; -: without)

mutations

____ in phages genome alters ability to produce plaques

natural

______ transformation occurs in a wide variety of bacteria

bacteria, viruses

__________ and __________ account for 1/4-1/3 of human deaths worldwide

davis

__________ later showed bacterial strains must make physical contact for transfer to occur

bacterial resistance

____________ to antibiotics is a serious worldwide problem

distance between genes

_______________ is determined by comparing their times of entry during an uninterrupted conjugation experiment

Relaxase

accessory protein released from relaxosome that remains bound to the end of the t-DNA

haploid

bacteria are usually _____________

asexually

bacteria reproduce _____________

competent cells

bacterial cells able to take up DNA

genetic material, protein coat

bacteriophages are composed of ___________ surrounded by a _____________

bacteria

can acquire genes that breakdown the antibiotic, pump out of cell/block inhibiting effects

auxotrophs

cannot synthesize a needed nutrient

calcium chloride, high temp shock

cells can be made competent in the lab by treatment w/ ________ and _____________

plaque

clear area on otherwise opaque bacterial lawn on agar surface of petri dish

Benzer

collected many rll mutant strains that can form large plaques in E. coli B and none in E. coli k12

competence factors

competent cells carry genes that encode proteins called...

HGT

conjugation, transformation and transduction are examples of...

order, distance

cotransduction is used to determine the ______ and ______ between genes that lie fairly closely together

Hayes

demonstrated conjugation between an Hfr and F- strain involves transfer of a portion of the Hfr bacterial chromosome

Cavalli-Sforza

discovered a strain of E. coli that was efficient at transferring chromosomal genes -- Hfr (1950s)

Griffith

discovered transformation in 1928 while working w/ strains of Streptococcus pneumoniae

conjugation bridge

during conjugation, a _____________ provides a passageway

competence factors

facilitate binding, uptake, and subsequent incorporation of DNA into bacterial chromosome

plasmid

general term used to describe extra chromosomal DNA, that is usually not required for survival of cell, can provide advantages in certain environments

1.5-2 hours

generally, it takes _________ for the entire Hfr chromosome to be passed into the F-cell

genetic diversity

genetic transfer in bacteria enhances...

+

genotype of bacterial cells that grew on plates has to be: met__, bio__, the__, leu__, thi__

dna repair enzymes

heteroduplex DNA is repaired by...

imprecise

in some cases, the integrated F factor is excised in an __________ fashion

heteroduplex

in transformation, a region of mismatch caused by sequence differences between the two alleles

bacteriophage

virus that specifically attacks bacterial cells

are not

viruses _____ living

traits

viruses have unique biological structures/functions, and therefore have...

existence, replication

viruses rely on host cell for _____ and _________

bacteriophage

viruses that infect bacteria, contain their own genetic material that governs traits

antibiotics

widely used to treat human infections and increase health/size of livestock

conjugation

type of horizontal gene transfer that involves direct physical contact

transformation

type of horizontal gene transfer that involves uptake from the environment

transduction

type of horizontal gene transfer that involves viruses

antibiotic resistance, virulence

types of genes acquired through HGT are varied and include genes that confer _____________ and _________

natural, artificial

types of transformation (2)

minutes

units of conjugation, refer to relative time it takes for genes to first enter an F- recipient during experiment

e. coli

lederberg and tatum were studying strains of _______ that has different nutritional growth requirements

prototrophs

make all their nutrients from basic components

conjugate

many, but not all bacteria can ____________

complementation test

method of discovering whether two mutations are in the same or separate genes

do not

most conjugations ________ last long (only a portion of Hfr chromosome gets into the F- cell)

dominant, loss of functions

mutations are not masked by ___________ genes, which makes it easier to identify _____________ mutations in bacteria than in eukaryotes

donor

only certain strains of bacterium can act as _____ cells

lysis, phages

plaque is caused by the ____ of bacterial cells as a result of the growth/replication of ______

are, easy

plaques _______ visible to the naked eye, so mutation is ____ to genetically analyze

transformation

process by which a bacterium will take up extracellular DNA released by damage or dead bacteria

horizontal gene transfer

process in which an organism receives genes from another organism w/out being a direct offspring

Relaxosomes

protein complex encoded by the F-factor. makes a cut at the origin of transfer and begins to separate the DNA strands

DNA Relaxase complex

recognized by the coupling factor and transferred to the exporter

cotransduction

refers to the packaging and transfer of two closely-linked genes

conjugation

refers to the transfer of DNA from one bacterium to another following direct cell-to-cell contact

genetic transfer

researchers rely on ____________, a segment of bacterial DNA transferred from one bacterium to another

electroporation (electrical shock)

secondary way cells can be made permeable to DNA

episome

segment of DNA that can exist as a plasmid and can integrate into the chromosome

chromosome DNA, recombine

the F- cell picks up __________ from the Hfr cell, can _______ w/ the homologous region on chromosome of recipient cell

bacterial chromosome

the integrated F factor may carry genes that were once found on the __________ (F' factors)

transduction

transfer of DNA from one bacterium to another via a bacteriophage