Chapter 14 Regulation Of Gene Transcription

Front 1

Catobolic pathway

Back 1

molecule is broken down, for energy or components
- ex. sugar metabolism and fat breakdown

Front 2

What is the name of the molecule being broken down?

Back 2

Catabolyte

Front 3

What is an anabolic pathway?

Back 3

When build up of product from components is seen
- ex. amino acid synthesis and nucleotide synthesis

Front 4

The Lac Operon

Back 4

-Polycistronic RNA, or one MRNA with 3 genes on it
-All needed to metabolize lactose
- B-galactosidase, permease, and Transacetylase

Front 5

E. Coli and lactose

Back 5

-E. Coli preferentially uses glucose for energy
-If glucose is present, it won't use other sugars
-Will shift to other sugars like lactose or arabinose when no glucose present

Front 6

Back 6

Expression of lac operon in response to lactose is decreased when lactose is removed

Front 7

b-galactosidase activity can be easily measured

Back 7

Front 8

What is an Operon?

Back 8

Unit under transcriptional control of operator

Front 9

What is an Operator?

Back 9

DNA sequence bound by a repressor that regulates transcription

Front 10

What is a Repressor?

Back 10

Protein that inhibits transcription

Front 11

What is an Apaprotein?

Back 11

protein that can bind a small molecule when athe small molecule is not bound

Front 12

lac operon model
-Repressor gene
-promoter of repressor protein
-operator
-Structeral genes

Back 12

Front 13

Mechanism of Lac operon regulation

Back 13

Repressor is normally bound to the operator, preventing transcription
Presence of lactose leads to allolactose. Allolactose binds to the repressor and makes it fall off the operator
With no repressor bound, transcription can proceed and the lac genes are transcribed

Front 14

Mechanism of CRP activation

Back 14

-CRP binds to cyclic AMP, produced when glucose is low
-CRP+cAMP binds to CRP response element on DNA
- -35 box of CRP-activated promoters is very weak
- alpha subunit of polymerase contacts CRP, makin gup for weak -35 box and enhancing trtanscription

Front 15

E. Coli lac operon requires what?

Back 15

CRP

Front 16

gal Operon is subjecto to what type of regulation?

Back 16

Negative and Positive

Front 17

What causes DNA looping and repression of the gal operon?

Back 17

Gal repressor and HU
-gal repressor binds to Operators
-HU loops promoter around itself

Front 18

CRP-RNA polymerase interactions at class II cAMP-dependant promoters

Back 18

Front 19

Arabinose operon

Back 19

-Similar to lactose
-Uses Ara repressor for negative regulation and CRP for positive regulation
-Difference is how binding of arabinose affects repressor
-Operator is seperated into three regions

Front 20

araBAD promoter region has multiple regulatory elements

Back 20

yes

Front 21

AraC undergoes a conformation change when?

Back 21

After binding arabinose to araC dimer (repressor)