Unit 3-Molecular Genetics Lesson 6 1.0-2.0

Question 1

What does lactose do for prokaryotes?

Answer 1

It is a potential source of energy for prokaryotes.

Question 2

Lac Operon is what?

Answer 2

A cluster of three genes that code for the proteins involved in lactose metabolism.

Question 3

What are the 3 components of Lac Operon?

Answer 3

Promoter Site
Operator
Coding Regions

Question 4

What is the function of the Promoter Site?

Answer 4

where DNA transcription begins

Question 5

What is the function of the Operator?

Answer 5

The sequence of the bases that controls transcription

Question 6

What is the function of the Coding Regions?

Answer 6

Code for the various enzymes that metabolize lactose.

Question 7

What is located upstream from the Lac Operon? Which does what?

Answer 7

A gene that codes for a repressor protein.

Question 8

What does the Lac Operon do?

Answer 8

takes cues from the environment and regulates the production of the lactose metabolizing proteins

Question 9

With regards to the Lac Operon, what is the repressor protein called?

Answer 9

lacI or lac repressor

Question 10

What occurs in the absence of lactose?

Answer 10

the lac repressor is active and binds to the operator,

Question 11

What does the Lac Oppressor keep RNA Polymerase from doing?

Answer 11

binding to the promoter and stops the lactose metabolizing enzymes from continually being synthesized

Question 12

What does the Lac Oppressor do in the presence of lactose?

Answer 12

some of it binds to a site on the lac repressor, rendering it inactive, this makes it unable to bind to the operator and block transcription

Question 13

What does Trp Operon do?

Answer 13

Same thing as Lac Operon - except codes for the protein Tryptophan

Question 14

What is tryptophan important for?

Answer 14

Building proteins

Question 15

What does trp operon have that is the same as lac operon?

Answer 15

The same structure

Question 16

What is the repressor protein called for Trp Operon?

Answer 16

trp repressor

Question 17

What occurs in the absence of tryptophan?

Answer 17

the repressor protein is in the inactive state and does not bind to the operator,
RNA polymerase is able to bind to the promoter region and the transcription of the genes to produce tryptophan can proceed