4.6 Regulation of Gene Expression in Bacteria Part 2 Flashcards
What are the three structural genes in the lac open?
lacZ
lacY
lacA
What does the lacZ gene encode for?
b-Galactosidase
What does the lacY gene encode for?
permease
What does the lacA gene encode for?
transacetylase
What does b-galactosidase do?
converts lactose into glucose and galactose
What does permease do?
facilities lactose entry into the bacterial cell
What does transacetylase do?
help remove toxins that are built up by lactose digestion
What lies just upstream of the three structural genes of the lac operon?
promotor-operation regulatory region
What do studies with the lac operon rely on?
use of chemical analogs of lactose such as IPTG
What is IPTG known as?
gratuitous inducer
What are gratuitous inducers?
can active genes naturally but they do not act as substrates for the enzymes that are synthesized
What did the use of research using IPTG show?
lacI gene
Where is the lacI gene found?
upstream of the promotor-operator
What is the lacI gene?
repressor gene that encodes for a repressor molecule
What is the function of the lacI gene?
when lactose is not present the lacI gene actively makes repressor proteins that bind to the DNA sequence of the operator
What does the presence of lactose do to the lacI gene?
sugar can bind to the repressor molecule to change its shape so it cannot bind to the operator region and turn it off
What are sRNAs?
small noncoding RNAs
How long are sRNAs?
50-100 nucleotides long
What is the function of sRNAs?
directly involved in the regulation of gene expression
What is the general mechanism of sRNAs?
bind to the nucleotide sequence of genes to either block or enhance gene activity
