What is the Central Dogma
DNA Transcribed to RNA
RNA Translated to PROTEIN
What is the initiation codon?
What is the termination codon?
What is a DEGENERATE CODE?
A degenerate code allows multiple codons to encode for the same amino acid
What is the Jacob-Monod Model?
The Jacob-Monod model of repressors and activators explains how operons work.
What are OPERONS?
Operons are inducible or repressible clusters of genes transcribed as a single mRNA
ON or OFF Switch for gene expression
What are the 4 sites on an Operon?
What do each of the four sites of the Operon do?
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.
What is the difference between a positive and negative control in an operon system of transcription?
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
What is the difference between an Inducible system and a Repressor 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)
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)
What are Transcription Factors?
Transcription factors search for promotor and enhancer regions / Response elements in the DNA.
What are the two sites on a transcription factor?
DNA binding domain
find promotor region and enhancer or response element
- RNA polymerase
- Histone Acetylases
Explain how enhancers work.
out side of promotor regions are recognized by
Transcription Facotors (and they bind)
Many Response elements together make an
enhancers allow control of one gene by many signal molecules, like
cAMP, Cortisol, Estrogen
(which bind to specific receptors)
Describe Histone Acetylases
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
Describe DNA Methylation
DNA Methylases add methyl groups to Nucleotides
CYSTOSINE and ADENINE Groups
Transcription therefore decreases
Methylation is observed in higher concentration on Heterochromatin