MIBO 3500 EXAM 2 QUESTIONS AND ANSWERS
Frederick griffith - Answers -studied streptococcus pneumoniae in mice
- hypothesized that bacteria could "transfer" information to each other
- S strain -> host death
- R strain -> not fatal
- pre-killing S strains prevents illness
- killed S plus live R is fatal
Conjugation - Answers -horizontal gene transfer requiring cell to cell contact
- two cells brought together by pilus on the donor
- relaxase assists in DNA transfer
- requires presence of transferable plasmids -> contain all genes needed for pilus
formation and DNA export
Prokaryotic genomes - Answers -~130-14000 kb
Very little non-coding DNA (less than 15%)
Operon - Answers -a gene can operate independently or together with others in an
___________
Regulon - Answers -collection of genes or persons with a unified biochemical purpose
RPOS - Answers -"starvation" regulon
DNA supercoiling - Answers -positive: overwound DNA
- archaea (low ph)
Negative: underwound DNA
- bacteria & archaea
Type 1 topoisomerases - Answers -usually single proteins
Cleave one strand of DNA
Type II topoisomerases - Answers -have multiple subunits
Cleave both strands of DNA (ds break)
EX: DNA gyrase grabs one section and introduces a ds break, then passes the intact
strand through the ds break
Replication from a single origin - Answers -after initiation, replication bubble forms
- two replication forks that move in opposite directions around chromosome and ends at
terminus
Dnaa - Answers -initiates replication (e coli)
As cell grows, levels rise
, Seqa - Answers -inhibits replication (e coli)
Binding, helicase (dnab) - Answers -__________ causes DNA to prepare for being
melted open by the _________
DNA polymerase III - Answers -main replication polymerase
- can also scan for mismatch bases (causing exonuclease activity)
- once removed, elongation continues
Rnase H - Answers -removes RNA primers
Termination replication - Answers -topoisomerase IV catalyzes a breaking & rejoining
event that resolves the link
**topoisomerase II
Transformation, conjugation, transduction - Answers -3 forms of gene transfer
Transformation - Answers -importing free DNA into bacterial cells
- for natural _______________, cells need to be competent (able to intake free DNA
from the environment)
- others require artificial manipulation -> perturbing membrane chemically (cacl2) or
electrocorporation methods
Gaining antibiotic resistance - Answers -advantage of being competent
Gram positive transformation - Answers -requires transformasome -> facilitates uptake
of DNA
- typically imports ssdna
- needs to be induced
Competence generated by quorum sensing -> as bacteria grow, competence factor
(CF) accumulates
- at specific levels, CF will induce genetic program that induces transformasome
Gram negative transformation - Answers -transform DNA without the use of
competence factors -> are either always competent or become competent when starved
- do not use transformasomes
- sequence specific -> limits gene exchange
E coli fertility factor (F) - Answers -F+ = genetic donors
F- = recipients
Membrane proteins encoded by F+ bacteria prevent conjugation with other F+
Frederick griffith - Answers -studied streptococcus pneumoniae in mice
- hypothesized that bacteria could "transfer" information to each other
- S strain -> host death
- R strain -> not fatal
- pre-killing S strains prevents illness
- killed S plus live R is fatal
Conjugation - Answers -horizontal gene transfer requiring cell to cell contact
- two cells brought together by pilus on the donor
- relaxase assists in DNA transfer
- requires presence of transferable plasmids -> contain all genes needed for pilus
formation and DNA export
Prokaryotic genomes - Answers -~130-14000 kb
Very little non-coding DNA (less than 15%)
Operon - Answers -a gene can operate independently or together with others in an
___________
Regulon - Answers -collection of genes or persons with a unified biochemical purpose
RPOS - Answers -"starvation" regulon
DNA supercoiling - Answers -positive: overwound DNA
- archaea (low ph)
Negative: underwound DNA
- bacteria & archaea
Type 1 topoisomerases - Answers -usually single proteins
Cleave one strand of DNA
Type II topoisomerases - Answers -have multiple subunits
Cleave both strands of DNA (ds break)
EX: DNA gyrase grabs one section and introduces a ds break, then passes the intact
strand through the ds break
Replication from a single origin - Answers -after initiation, replication bubble forms
- two replication forks that move in opposite directions around chromosome and ends at
terminus
Dnaa - Answers -initiates replication (e coli)
As cell grows, levels rise
, Seqa - Answers -inhibits replication (e coli)
Binding, helicase (dnab) - Answers -__________ causes DNA to prepare for being
melted open by the _________
DNA polymerase III - Answers -main replication polymerase
- can also scan for mismatch bases (causing exonuclease activity)
- once removed, elongation continues
Rnase H - Answers -removes RNA primers
Termination replication - Answers -topoisomerase IV catalyzes a breaking & rejoining
event that resolves the link
**topoisomerase II
Transformation, conjugation, transduction - Answers -3 forms of gene transfer
Transformation - Answers -importing free DNA into bacterial cells
- for natural _______________, cells need to be competent (able to intake free DNA
from the environment)
- others require artificial manipulation -> perturbing membrane chemically (cacl2) or
electrocorporation methods
Gaining antibiotic resistance - Answers -advantage of being competent
Gram positive transformation - Answers -requires transformasome -> facilitates uptake
of DNA
- typically imports ssdna
- needs to be induced
Competence generated by quorum sensing -> as bacteria grow, competence factor
(CF) accumulates
- at specific levels, CF will induce genetic program that induces transformasome
Gram negative transformation - Answers -transform DNA without the use of
competence factors -> are either always competent or become competent when starved
- do not use transformasomes
- sequence specific -> limits gene exchange
E coli fertility factor (F) - Answers -F+ = genetic donors
F- = recipients
Membrane proteins encoded by F+ bacteria prevent conjugation with other F+
