What is the lac operon? How is it controlled?

1
What is the lac operon? How is it controlled?

• QOD

2
Section 11-1

• Control of Gene Expression

3
Gene Expression

• Only some genes are expressed at any given time
• Cell specialization
• Two steps
• Transcription regulatory sites
• Translation

4
The Lac Operon

• Jacob and Monod
• Studied gene expression in lac operon of E. Coli
• Structural genes
• Promoter
• Operator
• Operon

5
(No Transcript)
6
Controlling the Lac Operon

• Repression
• Repressor protein
• Regulator gene
• Activation
• Inducer

7
Gene Expression in Eukaryotes

• Challenges
• Larger genome
• Several chromosomes
• Specialized cells
• No operons

8
How are genes controlled in eukaryotic organisms?

• QOD

9
Structure of Eukaryotic Genes

• Control before and after transcription
• DNA is coiled affects gene expression
• Euchromatin
• Heterochromatin
• Introns-Exons
• Options for producing different proteins
• Role for introns?

10
More on expression

• Control after transcription
• Locations
• Pre-mRNA
• Splicing mRNA exons Spliceosomes
• Alternative splicing
• RNA as enzymes ribozymes
• Enhancer control
• Enhancer region
• Transcription factors

11
Removal of Introns After Transcription
Section 1 Control of Gene Expression
Chapter 11
12
Controlling Transcription in Eukaryotes
Section 1 Control of Gene Expression
Chapter 11
13
How do complex multicellular organisms develop
from an embryo?

• QOD

14
Section 11-2

• Gene Expression and Development

15
Cell Differentiation

• Morphogenesis
• Homeotic (Hox) genes
• Homeobox 180 base pairs
• Regulatory proteins turn genes on/off
• Similar sequences found in many eukaryotic
  organisms

16
(No Transcript)
17
(No Transcript)
18
(No Transcript)
19
Cancer

• Tumor
• Benign tumor
• Malignant tumor
• Types
• Carcinomas
• Sarcomas
• Lymphomas
• Leukemia

20
The Cell Cycle

• Normal Cell needs
• Adequate nutrition
• Attached to other cells, membrane, fibers
• Stop dividing when become crowded
• Cancer-causing Agents
• Growth factors and mutations
• Carcinogens
• Mutagens

21

• More Causes
• Genetic factors
• Environmental factors
• Cigarette smoke
• Air and water pollution
• UV radiation
• Viral infection
• Prevention
• Dietary methods
• Behavior modification

22
More on Causes Genes

• Oncogenes/Proto-oncogenes
• Tumor-suppressor genes
• See Fig. 11-10, p. 214
• Viruses

23
Effect of Mutation on Gene Expression
Section 2 Gene Expression in Development and Cell
Division
Chapter 11
24
Fig. 3.23
25
Stem Cells - Properties

• Undifferentiated (unspecialized) cells
• Differentiate to any type of cell based on
  signals
• Depending on potency
• Self-renewing
• Mitosis ? differentiated cell another stem cell

26
Potency of Stem Cells

• Totipotent
• Zygote
• Pluripotent
• Embryonic
• Multipotent
• Adult

27
Sources of stem cells

• Embryonic
• From blastula stage of developing embryo (within
  first approx. 2 weeks)
• Pluripotent
• Adult
• Only in certain tissues (Brain, Bone marrow)
• Multipotent
• Induced Pluripotent Stem Cells (IPS)
• Somatic cell ? Pluripotent

28
Uses and Hurdles

• Potential Uses
• Cure diseases
• Repair spinal injuries/brain injuries
• Cloning organs
• Hurdles
• Signals
• Turning genes on/off is essential
• Culturing
• Maintaining lines
• Moral/Ethical debate