lect 5-bact. genome replication, expression and regulation 1 Flashcards
how are nucleic acids in DNA and RNA linked together
phosphodiester bonds
how do DNA and RNA differ
nitrogen bases they contain, sugars they contain, whether they are single or double stranded
how are polymers of amino acids linked
peptide bonds
define replication fork
where DNA is unwound
define replicon
origin and is replicated as a unit (entire genome in bacteria)
what does DnaA do
initiation of replication; binds OriC
what does DnaB do
helicase; breaks hydrogen bonds holding 2 strands of double helix together; promotes DNA primes activity; involved in primosome assembly
define DNA gyrase
relieves supercoiling of DNA produced as DNA strands are separated by helicases; separates daughter molecules in final stages of replication
SSB proteins
bind SS DNA after strands are separated by helicases
what does DnaC do
helicase loader; helps direct DnaB protein to DNA template
what does DNA primes do
synthesis if RNA primer; component of primosome
what does DNA polymerase III do
catalyzes most of the DNA synthesis that occurs during DNA replication; has exonuclease (proofreading)
DNA polymerase I
removes RNA primers; fills gaps in DNA formed by removal of RNA primer
what does ribonuclease H do
removes RNA primers
what does DNA ligase do
seals nicked DNA, joining DNA fragments together
what does Tus do
termination of replication
what does topoisomerase IV do
separation of chromosomes upon completion of DNA replcation
what does the beta clamp, alpha, portion and tau portion of the holoenzyme do
beta: binds to DNA, alpha forms the bond and tau helps stabilize for proofreading
what does the epsilon subunit of holoenzyme do
for fidelity and proofreading
what does helices do
unwinds DNA strands
what does DNA gyrase do
it is a topoisomerase that introduces negative supercoiling to help compact bacterial chromosome (reduces tension)
what is proofreading carried out by
polymerase 3 (epsilon portion)
what direction is the template strand of DNA read in
3’ to 5’ direction
what is the start codon
AUG
