Powerpoint 29 Flashcards
the information from the DNA that we need to adapt to our life right now
mRNA
the translator for the ribosome liks specific sequences to amino-acids
tRNA
RNA parts of the protein making machine
-16S a critical feature
rRNA
bacterial genes are organized into
operons
grouping of genes allow concerted
transcription and translation
generated a polycistronic message of multiple genes required for
function
constantly synthesized
-enzymes of glycolysis
constitutive
not trgulartly produced
- turned on in certain conditions
- B-galactosidase
Indicible
routinely synthesizes
-generally involved in biosynthesis
Repressible
mechanisms controlling transcription
regulatory region near promotor
protein binds to regulatory region and acts as a
on/off switch
Binding protein can act as a repressor or activator. A repressor
blocks transcription
a activator
facilitates transcription
the synthesis of a strand of mRNA from DNA template strand is synthesized by *RNA polymerase
Transcription
Transcription initiation in prokaryotes occurs when a _____ binds the promoter orienting a RNA-polymerase
sigma factor
recognizes elements in upstream region of DNA -35 and -10 to the start site
RNA polymerase “seeing eye dog”
the third base is known as the
wobble base
the usage of particular codons is different between different organisms, this is called
CODON BIAS of an organism
is 4-8 base pairs before the first AUG. Also called the ribosome binding site
Shine-Dalgarno
sequence is complementary to one in the 16s rRNA
Shine-Dalgarno
form peptide bonds along the way while the robosome continues down the strand of mRNA
amino acids
is terminated when the ribosome’s come to a stop or nonsense codon
Translation
- at this point the ribosomes separate
- the new polypeptide chain is released
after translaion is terminated
-then the ribosome and the mRNa are free to begin translation again
example of induction of gene expression
lac operon
Near the operon on the DNA is a regulatory gene called the l gene
-this codes for the repressor protein
Lac operon
when lactose is absent the repressor protein binds to the
operator region
the biding of the repressor gene prevents RNA polymerase from transcribing the structual genes so
No mRNA is made and no enzymes are synthesized
when lactose is present the ___ binds to lactose instead of the operator and is released for DNA
repressor
with the repressor bound to the lactose, RNA polymerase is able to bind to te promoter and transcribe the
structural gene
acts as the induced by keeping the repressor from binding to the operator
Lactose
is allows the transcription of the structural genes
Lactose
