exam three (microbial genetics) Flashcards
small, self replicating extrachromosomal genetic elements
plasmid
all genetic elements present in an organism
genome
streptococcus pneumoniae strain r gave a ____ appearance but s gave a ___ appearance
rough; smooth
mice with _ strain were killed not just sick like with other strain
S
griffiths mixed r as a live strain and s as dead strain and the colonies that showed up were all s and killed mice
what should have happened?
idea was that colonies should have been rough and not lethal because s stain was dead; transformation was discovered in this way
avery, macleod, and mcCarty added an RNase (takes out RNA) and a protease (takes out protein) in the smooth strand and then mixed it with r, what happened?
transformation continued to happen; mice dead and smooth colonies
avery, macleod, and mcCarty added a DNase in the smooth strand and then mixed it with r, what happened?
no transformation; rough colonies and not lethal
avery, macleod, and mcCarty finally mixed r with just DNA from s and what happened?
smooth colonies; dead mice (DNA is the element of transformation)
DNA to RNA
transcription
RNA to protein
translation
bacteria does ____ replication, very rapid
bi-directional
the bi-directional replication of bacteria has 2 ___ ___ but ___ start of replication origin
2 replication forks; one
what structure shows up when microbe is halfway through replication
the theta structure
in termination links of chromosomes; that are resolved by topoisomerases (eukaryotes)
catenanes
in termination dimerization are resolved by ____ in prokaryotes
recombinases
plasmid replication is very different; not ___ ___
bi-directional
eukaryotic genes have introns which are _____ regions and exons which are ____ regions
non-coding; coding
the bacterial gene only has ____ regions
coding
what are the promotor sites in bacteria?; they are ___ ____ binding (found in promotor; highly conserved)
-10, -35; rna polymerase
things that are upstream are to the ___ of the gene (5’ - 3’)
left
_____ is down stream
terminator
-10 is 10 base pairs ____ from gene
upstream
what is the transcription start site
+1 (upstream)
the promotor regions (-10, -35) guide _____ process
transcription
the leader sequence is between what
transcription and translation start site
the ribosome binding site is the _____ start site
translation
the bacteria has its own specific 5 subunit core enzyme (alpha, alpha, beta, beta’ and w) which is a?
rna polymerase
RNA polymerase binds with __ ___ in promotor region
sigma factor
sigma factor and core enzyme is called
holoenzyme
purpose is to help recognize promotor so core enzyme can attach
sigma factor (essential; once core enzyme binds, sigma can leave)
in Rho- dependent termination____ attaches to mRNA; influences polymerase and RNA to fall off in termination
Rho
factor independent termination has no ____
Rho
in factor independent termination there has to be ___ ___
inverted repeats
the inverted repeat is significant because it creates a ___ ____ structure (two inverted repeats will compliment)
stem loop
the factor independent termination also has __ rich region which are weak and that in combination with the loop will cause ____ to fall off
U rich; polymerase
transcription in eukaryote is complex; has splice sites and does alternate splicing to remove introns by _____
spliceosome
mature mRNA of eukaryotes has what two things
5’ cap & poly-a tail
the leader sequence in bacterial region is an ___ ____
untranslated region
the translation start codon is
AUG
e. coli ribosome binding site is
shine-dalgarno site
translation stop codon for bacterial translation
UAA, UAG, UGA
genes ordered one after another with one promoter; genes involved in same pathway
operon (all controlled by same promoter and terminator)
prokaryotes can couple ___ and ___ because they dont have to use DNA from nucleus
transcription and translation
transcriptional regulation:
most genes that are always expressed
constitutive
transcriptional regulation:
activated by a protein; activator protein binds near promotor; turns ON gene OFF (control of a gene that is turned OFF)
positive control
three levels of control for prokaryotes
transc. , translation, post- translational
transcriptional regulation:
uses repressor protein
(turning OFF something that is ON)
negative control
____ are down stream products that come from gene being transcribed and translated and activate a protein to help activate transcription (helps to control an activator)
inducer
___ ___ typically focuses on up or down regulating an always somewhat on gene
transcriptional regulation
allow some transcription even under repression
leaky promotors
two component system regulates ____
transcription
a sensor kinase is in the ____ and responding to it in the _____ is the response regulator
membrane, cytoplasm
the two component system senses and responds to _____ _____ (up regulate or down regulate transc.)
changing environment
the sensor kinases can respond to changes in _____; then internal response regulator turns genes on or off
osmolarity
attenuation is apart of _____ regulation
transcriptional
tryptophan synthesis operon is unique because the leader sequence is ____; why?
translated; has 4 attenuator sequences that give rise to stem loop
2 trp codons side by side is a ____ ____ (now microbe needs two to continue)
limiting factor
in low tryptophan levels, the ____ will pause and give mRNA to form stem loop called antitermination loop.
ribosome
the antitermination loop allows _____ to continue to make more tryptophen
transcription
in high tryptophan: terminator loop forms and stops transcription, why?
doesn’t need more trytophan
riboswitches are ____ regulation
transcription
riboswitches fold into ____ ___, a metabolite alters their folding structure
secondary structure
metabolites (down stream; come from gene) regulate transcription by interacting with ____ and changing its structure to turn transcription ___
riboswitch; off (riboflavin)
translation start site is upstream and called
RBS
