Unit 2: Lac Operon Flashcards
1
Q
lacZ vs LacZ
A
- lacZ is the gene that codes for the LacZ enzymes
2
Q
What are the Lac operon and Mal operon functions?
A
- both code for enzymes involved in breakdown of sugars that can be used for carbon and energy
3
Q
What is significant about the Lac operon and Mal operon being environmentally regulated?
A
- genes only need to be expressed IF the sugars they break down are available to the cell
4
Q
What sugars to the Lac operon and Mal operon break down?
A
- lactose and maltose
5
Q
How are lactose and maltose inducers?
A
- they are signals that turn on relevant operons, so they “induce” the operon expression
6
Q
What does the lac operon contain?
A
- a set of genes that allow bacteria to break down lactose into glucose and galactose, which can be used for energy and carbon
7
Q
What are the 3 proteins that the Lac Operon codes for?
A
- LacZ, LacyY, and LacA
8
Q
LacZ
A
- a beta-galactosidase enzyme that cleaves lactose in hlaf
9
Q
LacY
A
- a permease transport protein that allows lactose to enter the cell
10
Q
LacI (3)
A
- regulatory protein that regulates expression of lac operon via negative regulation (it is a repressor)
- gene that encodes for LacI is upstream of the operon
- LacI is constitutively expressed
11
Q
How is a small amount of LacY always present in the cell membrane?
A
- any repressor will eventually detach from the operator just long enough for a RNA Polymerase to slip by and transcribe the operon to allow lactose to enter the cell in a “just in case” situation
12
Q
What are the notable exception to basal transcription? (2)
A
- if a mutation destroys a promoter, there is nowhere for the transcription factors to bind to and recruit RNA Polymerase
- in eukaryotes with packaged DNA, only unpackaged DNA can be described, any packaged genes are not transcribed
