chapter 9 part 2 Flashcards
(34 cards)
spliceosome
Occurs only in eukaryotic recognizes exon-intron junctions enzymatically cuts them loops introns, joins exons end to end completed mRNA strand
introns
clip out
do not want in
intervening sequences of bases
viruses contain
double-stranded DNA
single-stranded RNA
double-stranded RNA
single-stranded DNA
Operons
located only in bacteria and archaea
coordinated set of genes regulated as a single unit
inducible operons
glucose+ galactose (Lactose)
need turned on for coding of enzymes
catabolic enzyme
Repressible operons
anabolic enzymes
always on
lactose operon
regulator
a gene that codes for the repressor
Repressor
a protein capable of repressing the operon
Promoter
recognizes by RNA polymerase
operator
acts as an on/off switch for transcription
structural locus
3 genes
coding for different enzymes needed to catabolize lactose
allosteric
2 binding sites
one for operator sequence on DNA and another for lactose
In absence of lactose, repressor binds to operator, blocking transcription of structural genes
repressible operon
on mode
only be turned off when nutrient is not longer required
corepressor
excess nutrient
block the action of the operon
phase variation
bacteria turning on and off
phenotypic changes
phase variations
bacteria ma change cell surface markers
change attachment fimbriae and capsule production
difference between prokaryotic and eukaryotic transcription and translation
cotranslational translation only occurs in bacteria and archaea
drugs that inhibit protein synthesis
rifamycins
actinomycin D
control locus
promotor- RNA polymerase binds
operator-
Structural locus
codes for 3 enzymes
recombination
one bacteria donates DNA to another bacterium
conjugation
donor cell with pilus
fertility plasmid in donor
both donor and recipient alive
direct
transformation
free donor DNA
live, competent recipient cell
indirect
transduction
donor is lysed bacterial cell
live recipient
indirect
