L.6 DNA Regulations

Question 1

What is the Central Dogma

Answer 1

DNA Transcribed to RNA

RNA Translated to PROTEIN

Question 2

What is the initiation codon?

What is the termination codon?

Answer 2

AUG

UAG

UGA

UAA

Question 3

What is a DEGENERATE CODE?

Answer 3

A degenerate code allows multiple codons to encode for the same amino acid

Question 4

What is the Jacob-Monod Model?

Answer 4

The Jacob-Monod model of repressors and activators explains how operons work.

Question 5

What are OPERONS?

Answer 5

Operons are inducible or repressible clusters of genes transcribed as a single mRNA

ON or OFF Switch for gene expression

Question 6

What are the 4 sites on an Operon?

Answer 6

R POS

Regulator

Promotor

Operator

Strutural

Question 7

What do each of the four sites of the Operon do?

Answer 7

R POS

Regulator; Makes Repressor (Codes the protein)

Promotor; Holds the RNA Polymerase

Operator: Operator is the site of repressor binding

Structural: We find the GENE of interest here.

Question 8

What is the difference between a positive and negative control in an operon system of transcription?

Answer 8

Negative Control:

A binding of a protein such as repressor to the operator stops transcription of a protein.

A Positive control:

A binding of a protein increases transcription of a protein

Question 9

What is the difference between an Inducible system and a Repressor System?

Answer 9

Inducible system

When Repressor is on operator under normal condition thus not allowing transcription, can be turned on by an Inducer, thus pulling it awat from operator (lac Operon)

Repressible

When Repressor is not bound to operator undernormal conditions, turning it on with a corepressor will allow it to attach and stop transcription (trp Operon)

Question 10

What are Transcription Factors?

Answer 10

Transcription factors search for promotor and enhancer regions / Response elements in the DNA.

Question 11

What are the two sites on a transcription factor?

Answer 11

DNA binding domain

find promotor region and enhancer or response element

Activation Domain

Transcription factor

Regulatory proteins

• RNA polymerase
• Histone Acetylases

Question 12

Explain how enhancers work.

Using

Response elements

Transcription Factors

Enhancers

Signal Molecules

Answer 12

Response Elements

out side of promotor regions are recognized by

Transcription Facotors (and they bind)

Many Response elements together make an

Enhancer

enhancers allow control of one gene by many signal molecules, like

cAMP, Cortisol, Estrogen

(which bind to specific receptors)

Question 13

Describe Histone Acetylases

Answer 13

Transcription factors sometimes recruit COACTIVAORS

one of which is Histone Acetylases

these Acetylate Lysine residues found in aminoterminal regions of Histone protein

therefore adding POSITIVE charges and decresing the strenght between DNA and histone Bonds, opening chromatin and Increasing gene expression

Question 14

Describe DNA Methylation

Answer 14

DNA Methylases add methyl groups to Nucleotides

CYSTOSINE and ADENINE Groups

Transcription therefore decreases

Methylation is observed in higher concentration on Heterochromatin