Ch 14 Regulation of Cellular Processes

Question 1

Constitutive genes

Answer 1

Gene that is expressed at equal levels at all times

Question 2

Inducible genes

Answer 2

Genes whose expression can be increased by a regulatory molecule

Question 3

Inducer

Answer 3

Small molecule that stimulates the syn of an inducible enzyme

Question 4

Repressive genes

Answer 4

Gene whose product is a protein whose level drops in the presence of a small repressor molecule. If part of biosyn pathway——> repressor is usually the product of that pathway

Question 5

Corepressor

Answer 5

Small molecule that binds a transcription repressor protein, activating it and inhibiting enzyme production

Question 6

Transcription factors

Answer 6

Proteins that bind near promoter region to help initiate and/or prevent transcription of a gene. (Usually dimers)

Question 7

Domainl

Answer 7

Part of a protein with specific shape and function

Question 8

Negative control

Answer 8

Reg of transcription by repressor protein. When bound, trans repressed

Question 9

Positive control

Answer 9

Control of transcription by activator protein. When bound level of trans increased

Question 10

Operator

Answer 10

Area of DNA that repressor binds to (overlaps or downstream of promoter) prevents RNA pol binding or movement

Question 11

Activator binding sites

Answer 11

DNA seq where activators bind (usually upstream of promoter) allows RNA pol to bind

Question 12

Operon

Answer 12

Related structural genes, a promoter, an operator and/or activator binding site that controls expression of the operon

Question 13

CAP

Answer 13

Catabolite activator protein. Regulates the lac operon in regards to the presence of glucose (Will repress if glucose is present)

Question 14

Regulon

Answer 14

Collection of related operons controlled by activator proteins

Question 15

Catabolite repression

Answer 15

Regulatory mech that suppresses the expression and activity of metabolic systems of a secondary C source when preferred source is present

Question 16

Attenuation

Answer 16

When transcription is stopped within the leader

Question 17

Trp attentuation steps (high levels trp)

Answer 17

Repressor does not block transcription——> trans begins and leader is translated.——> if trp present the two trp codons filled trans proceeds to stop codon——> 3-4 loop (term loop) forms RNA pol booted from DNA

Question 18

Trp attenuation steps ( low trp )

Answer 18

Repressor does not bind,trans begins——> as translation begins not enough charged trp tRNA to fill 2 codons, Ribosome pauses——> b/c of pause 2-3 loop forms——> blocks formation of 3-4 term loop——> transcription of trp operon proceeds

Question 19

sRNA

Answer 19

Small RNA. Binds to mRNA to act in regulation. Can be inhibiting or inducing

Question 20

Antisense RNA

Answer 20

SsRNA with bases complimentary to a segment of a target RNA molecule. Usual alters target when bound

Question 21

Lactose present glucose absent (Lac operon)

Answer 21

Allolactose binds repressor protein, inactivating it——> CAP activated with cAMP bound binds CAP site——> RNA pol binds promoter stabilized by bound CAP and transcription proceeds

Question 22

Lactose present, glucose present ( Lac operon)

Answer 22

Allolactose binds regulator protein and inactivates it——> cAMP does not bind and activate CAP——> CAP does not bind CAP site, RNA pol can not bind——> no transcription

Question 23

No lactose, no glucose (Lac Operon)

Answer 23

Repressor remains activated since no Allolactose to bind it——> CAP is activated by cAMP, binds CAP site——> RNA pol can bind but can not proceed with transcription b/c blocked by repressor protein