Operons Structural gene Operon Polycistronic mRNA Operato - PowerPoint PPT Presentation

1 / 17
About This Presentation
Title:

Operons Structural gene Operon Polycistronic mRNA Operato

Description:

Operons Structural gene Operon Polycistronic mRNA Operator Regulator gene Repressor Overview animation PROMOTER---OPERATOR----gene 1 gene 2 gene 3 Regulator ... – PowerPoint PPT presentation

Number of Views:226
Avg rating:3.0/5.0
Slides: 18
Provided by: dmaccEduI
Category:

less

Transcript and Presenter's Notes

Title: Operons Structural gene Operon Polycistronic mRNA Operato


1
Regulation of Gene Expression
  • Operons

2
Operon System (bacteria)
  • Structural gene
  • Operon
  • Polycistronic mRNA
  • Operator
  • Regulator gene
  • Repressor
  • Overview animation

3
Operon Structure
  • PROMOTER---OPERATOR----gene 1gene 2gene 3
  • Regulator gene (located elsewhere on
    chromosome)

4
Negative controlshutting something down
5
Inducible Operons
  •  Normally OFF, induced (turned on) only when
    needed
  •  
  • Ex. Lac operon (3 enzymes for catabolism of
    lactose)
  • repressor binds at operator no transcription
  • lactose binds repressor, comes OFF operator
    Transcription can proceed!

6
This is the graphic from your textbook. I like
the one on the next slide better
7
The lac operon inducible operon
8
The lac operon inducible operon
Inducible operon animation (lac operon)
9
Repressible Operons
  • Normally ON, repressed (turned off) when not
    needed
  •  
  • Example Genes for amino acid biosynthetic
    enzymes
  • Arginine operon and tryptophan operon are
    examples.
  •  
  • Operon is actively transcribing
  • Arginine (or tryptophan) is synthesized
  • If arginine (or tryptophan) accumulates beyond
    useful levels, arg (trp) acts as COREPRESSOR
  • Corepressor repressor protein bind to operator,
    SHUT OFF OPERON

10
This is the graphic from your textbook. I like
the one on the next slide better
11
The trp operon repressible operon
12
The trp operon repressible operon
13
The trp operon regulated synthesis of
repressible enzymes
Repressible operon animation (trp operon)
14
Positive controlramping something up
15
  • Activator protein instead of a repressor.
  • The activator protein promotes the binding of RNA
    Polymerase to the promoter and thereby acts to
    increase mRNA synthesis.
  • Maltose operon is an example

16
Maltose operon
17
Global Control
  • Catabolite repression
Write a Comment
User Comments (0)
About PowerShow.com