Gene expression Flashcards
All Cells Must Precisely Regulate The Expression Of Genes To
Function As Coherent Biological Systems
This Ability Is Essential For All
Cells To Produce The Specific Set
Of Proteins & Specialized RNA
Molecules They Require To
Function
Independently As A Single-Cell species &
As A Critical Part Of A Multi-Cell
Species Like Us
Precise Gene Expression Enables Cells To
Maintain All Proteins & Specialized RNA Molecules At The
Proper Concentration
Each Of The 220 Human Cell Types Must Express A Unique Pattern Of Genes To
Produce The Distinctive Set Of Proteins & Specialized RNA Molecules It Needs To
Perform Its Bodily Function
The Gene Is Activated When The Cell Needs The Protein
the Gene Encodes Or Needs A Higher
Concentration
The Gene Is Deactivated When The Cell
Does Not Need The Protein The Gene Encodes
* Has The Proper Concentration Of The Protein The Gene Encodes
When A Receptor Recognizes An
Environmental Factor,
The Cell
Expresses The Genes That Code For
The Proteins The Cell Requires To
Respond To That Environmental Factor
The Operon
Is A Group Of Related Genes Clustered Together On The
Prokaryotic (Archaea & Bacteria) Chromosome
The Genes In The Operon Code For
Related Proteins That Perform A Specific
Cellular Function, Such As, Lactose Metabolism
The Lac Operon Of The
Bacterium, E. coli, That
Inhabits Your Lower
Intestine
Arranging Related Genes Into An Operon Facilitates
The Expression Of
Gene Regulation, Conserves Energy, And Conserves Molecular
Building Blocks
All Genes In An Operon Are Expressed (Activated) Or Repressed (Deactivated) As A Single
Unit Because
One Promoter Controls The Transcription Of All The Operon’s Genes
Only One Molecular Switch Is Required To
Regulate Operon Expression
After Translation, All The Proteins Required To
Catabolize Lactose Are
Clustered Together In The Cell
The Lac Operon Of The Bacterium Escherichia coli (E. coli
-E. coli Inhabits The Lower Human Intestine
- E. coli Has Access To The Nutrients In Breast Milk & Other Dairy Products
-The Lac (Lactose) Operon Enables E. coli To Metabolize Lactose (Milk Sugar)
The Lac Z Gene Codes For The
Beta-Galactosidase Enzyme That Cleaves Lactose To
Produce Glucose & Galactose
We Produce Lactase In The Small Intestine To Digest
Lactose In Dairy Products
The Lac Y Gene Codes For The
The Membrane Transport Protein, Permease, That Imports
Lactose
The Lac A Gene Codes For
Transacetylase Enzyme That Protects The Cell By Detoxifying
Poisonous Β-Galactosides & Increasing Their Export
The Promoter & Operator Are
The DNA Regulatory Elements That
Control Lac Operon Expression
Transcription Factors & RNA Polymerase Bind To
The Promoter To Enable
(Promote) Transcription
The Regulatory Lac I Repressor Protein Binds To The
Operator To Repress
Transcription
The Lac I Repressor Protein Is Required For
E. coli To Control
Lac Operon Expression
This Regulatory Protein Is
Encoded By The Lac I Gene
The Lac I Gene Is Not Part Of The
Lac Operon
When the Lac I Repressor Protein
-Binds To The Operator, The Lac
Operon Is Repressed Because RNA
Polymerase Cannot Bind To The
Promoter
-Does Not Bind To The Operator,
The Lac Operon Is Expressed
Because RNA Polymerase Binds To
The Promoter
