Z-Micro Exam 3- Regulation Of Gene Expression

Front 1

Regulation of Gene Expression

Back 1

control of transcription

Front 2

Methods of regulation of Gene Expression

Back 2

Info transfer

Repression blocks transcription

Induction initiates transcription of gene

Front 3

Info transfer method

Back 3

DNA--> RNA--> Protein

Front 4

How does repression regulate methods of gene expression?

Back 4

Co-repressor is usually the end product of a synthetic pathway – called feedback repression
A B C D E
b. Repressor is the regulatory protein that blocks transcription of genes that code for protein synthesis (ex: enzymes are not formed) OP (Fig 8.13)
c. Contrast with enzyme inhibition = control of existing enzymes
i. feedback inhibition controls existing

Front 5

How does induction initiate transcription of genes?

Back 5

Induction initiates transcription of gene
a. Inducer is substance that acts to start transcription
b. Often = catabolite (ex: lactose)

Front 6

Lactose Operon Model for Induction Control discovered
after study of ________.

Back 6

lactose genes in E. coli

Front 7

All ___________ contain all the genes to produce all enzyme products

Back 7

wild type E. coli

Front 8

True or False:
Most genes are turned off & produce protein products only when needed (true of eukaryotes as well)

Back 8

True

Front 9

What does Beta galactosidase (Z) do?

Back 9

Metabolizes lactose, breaks it down into glucose and galactose

Front 10

What does β galactoside permease (Y) do?

Back 10

Transports lactose into cell

Front 11

thiogalactoside transacetylase (A) does what

Back 11

metabolizes other disaccharides

Front 12

Components of the Operon (there's 2)

Back 12

a. Structural genes, which code for the 3 lactose enzymes (Z, Y, A)

b. Control region made up of 2 sites

Front 13

Function & Location of structural genes, which code for the 3 lactose enzymes (Z, Y, A)

Back 13

i. these genes specify a.a. sequence of protein

ii. these genes are (physically) located next to each other

Front 14

What are the two sites the Control region is made up of?

Back 14

i. Operator (O) – on/off switch
ii. Promotor (P) – (next to operator) where RNA polymerase binds to initiate transcription (in eukaryotes = TATABOX)

Front 15

True or false:

Regulator gene never makes repressor protein.

Back 15

False! It always (24/7) makes the repressor gene

Front 16

in absence of inducer allolactose (lac –allolactose), what happens?

Back 16

i. repressor protein is active & binds to operator (turning it off)
ii. promotor is blocked so RNA polymerase cannot synth RNA
iii. (therefore) no transcription of lac(tose structural) genes

Front 17

in presence of inducer allolactose, what happens?

Back 17

i. repressor protein is inactivated
ii. the operator is turned on
iii. RNA polymerase can transcribe the lac(tose) structural genes for translation into the 3 lac(tose) enzymes
iv. allolactose actually induces (stimulates) synthesis of lactose digesting enzymes

Front 18

2 types of enzymes

Back 18

inducible enzyme
constitutive enzymes

Front 19

inducible enzyme

Back 19

synthesis is initiated by catabolite inducer

Front 20

constitutive enzymes

Back 20

synthesized all the time & not subject to control (ex. pathways with enzymes always produced = glycolysis & Krebs cycle)