Gene regulation and the lac operon

genetics 211

produce enzyme when needed

what is the method bacteria use for enzyme synthesis?

disaccharide

lactose is a ____

beta galactosidase

cytoplasmic enzyme that hydrolyzes lactose

lac operon

set of genes that encode proteins involved in lactose metabolism and controlled by the same promoter

beta permease

membrane protein that transports lactose

beta trans acetylase

cytoplasmic protein that attaches acetyl CoA to lactose

lac operon 1

lactose is the inducer for the ____ gene (1)

gene i

What is the gene that encodes a repressor protein for the lac operon gene?

operator (DNA) and lactose

What are the 2 binding sites for the lac operon repressor protein or gene (i)?

true

true or false, gene (i) can only bind DNA or lactose and not both

lactose

gene i has a higher affinity towards what?

RNA polymerase transcribes lac operon

when lactose is present what does RNA polymerase do?

RNA polymerase doesnt bind

when lactose is not present, what does RNA polymerase do?

O^c

Which lac operon mutant is a mutation in the operator sequence preventing the repressor from binding?

high levels of B-gal, B-perm, and B-trans

what is the product of the O^c lac operon mutant

P-

Which lac operon mutant is a mutation in the promotor sequence preventing RNA polymerase from binding?

low levels of B-gal, B-perm, and B-trans

what is the product of the P- lac operon mutant?

i-

Which lac operon mutant is a mutation in the repressor protein i gene inhibiting DNA binding?

high levels of B-gal, B-perm, and B-trans

what is the product of the i- lac operon mutant?

i^s

which lac operon mutant is a mutation in repressor protein i gene that inhibits lactose binding so it remains bound to operator?

low levels of B-gal, B-perm, and B-trans

what is the product of the i^s lac operon mutant?

partial diploid cell with plasmid

what was created to distinguish lac operon mutants?

O^c and i^s

what are the dominant lac operon mutants?

P- and i-

what are the recessive lac operon mutants?

P- and i^s

what 2 lac operon mutants have the same phenotype of low levels?

O^c and i-

what 2 lac operon mutants have the same phenotype of high levels?

B-gal

what enzyme was measured to look at the function of the lac operon?

lacZ

what structural gene codes for beta- galactosidase?

lacY

what structural gene codes for beta-permease?

lacA

what structural gene codes for beta-transacetylase?

ok!

draw the 2 lac operon graphics from slide 15 in the lac operon slideshow