Regulation of gene therapy Prokaryotes and eukaryotes Lac operon Regulator Promoter

1. REGULATION OF GENE EXPRESSION

2.  Understand the concept of gene expression
 Describe basic mechanism of regulation of gene
expression in prokaryotes and describe lac operon
concept and its regulation
 Describe basic mechanism of regulation of gene
expression in eukaryotes
 Understand the concept of gene expression
 Describe basic mechanism of regulation of gene
expression in prokaryotes and describe lac operon
concept and its regulation
 Describe basic mechanism of regulation of gene
expression in eukaryotes

3. Gene expression is the combined process of the transcription
of a gene into mRNA and its translation into protein.
Genetic mutation alter the regulation or expression of gene
and results in dysfunc- tional or non
-functional protein
synthesis
Information, encoded in DNA, is transcribed into RNA and
then translated into protein. It is called the gene expression.
Thus, gene is expressed in terms of synthesis of protein.
Gene expression is the combined process of the transcription
of a gene into mRNA and its translation into protein.
Genetic mutation alter the regulation or expression of gene
and results in dysfunc- tional or non
-functional protein
synthesis
Information, encoded in DNA, is transcribed into RNA and
then translated into protein. It is called the gene expression.
Thus, gene is expressed in terms of synthesis of protein.

4. Expression of gene.

5.  The regulation of gene expression is essential for
metabolic functions, growth and development and
differentiation of tissues.
 The rate of expression of prokaryotic genes is
control- led mainly at the level oftranscription, mRNA
synthesis.
 Eukaryotes, however have a much larger and more
complex genome than prokaryotes. Gene expression in
eukaryotes is controlled by many ways.
 The regulation of gene expression is essential for
metabolic functions, growth and development and
differentiation of tissues.
 The rate of expression of prokaryotic genes is
control- led mainly at the level oftranscription, mRNA
synthesis.
 Eukaryotes, however have a much larger and more
complex genome than prokaryotes. Gene expression in
eukaryotes is controlled by many ways.

6. Types of Gene Regulation
There are two types of gene regulation:
 Positive regulation
 Negative regulation
Types of Gene Regulation
There are two types of gene regulation:
 Positive regulation
 Negative regulation

7. Positive Regulation
When the expression of genetic information is increased
by the presence of a specific regulatory element,
regulation is said to be positive. The element or molecule
mediating the positive regulation is said to be an
activator or inducer.
Positive Regulation
When the expression of genetic information is increased
by the presence of a specific regulatory element,
regulation is said to be positive. The element or molecule
mediating the positive regulation is said to be an
activator or inducer.

8. Negative Regulation
When the expression of genetic information is diminished
by the presence of a specific regulatory element,
regula- tion is said to benegative and element mediating
negative regulation is said to be a repressor.
Negative Regulation
When the expression of genetic information is diminished
by the presence of a specific regulatory element,
regula- tion is said to benegative and element mediating
negative regulation is said to be a repressor.

9. Types of Genes
There are two types of genes:
 Inducible gene
 Constitutive gene.
Types of Genes
There are two types of genes:
 Inducible gene
 Constitutive gene.

10. Inducible Gene
Inducible genes are expressed only when an inducer is present, e.g.
 Production of the enzyme β- galac- tosidaseis induced by the
presence of lactose in the prokaryotes
 Insulin is an inducer of the gene glucokinase of glycolysis in
human beings.
Constitutive Gene
Constitutive genes refer to genes whose expression is not regulated.
They are expressed at a constant rate. These are often referred to as
housekeeping genes.
Inducible Gene
Inducible genes are expressed only when an inducer is present, e.g.
 Production of the enzyme β- galac- tosidaseis induced by the
presence of lactose in the prokaryotes
 Insulin is an inducer of the gene glucokinase of glycolysis in
human beings.
Constitutive Gene
Constitutive genes refer to genes whose expression is not regulated.
They are expressed at a constant rate. These are often referred to as
housekeeping genes.

11. REGULATION OF GENE EXPRESSION IN
PROKARYOTES
In prokaryotes, the genes involved in a metabolic pathway
are often present in a linear fashion, called an operon. For
example:
 Lactose operon (Lac operon for regulation of
lactose metabolism)
REGULATION OF GENE EXPRESSION IN
PROKARYOTES
In prokaryotes, the genes involved in a metabolic pathway
are often present in a linear fashion, called an operon. For
example:
 Lactose operon (Lac operon for regulation of
lactose metabolism)

12. LACTOSE OPERON OR LAC OPERON
Model for the regulation of lactose metabolism by
E. coli.
Definition of Lac Operon
Lac operon is a coordinated unit of gene expression
to make the enzymes necessary to metabolize
lactose.
LACTOSE OPERON OR LAC OPERON
Model for the regulation of lactose metabolism by
E. coli.
Definition of Lac Operon
Lac operon is a coordinated unit of gene expression
to make the enzymes necessary to metabolize
lactose.

13. Structure of the Lac Operon
1. Regulatory gene (lac i) produces a repressor protein
2. A promoter site (P) for the binding of RNA
poly- merase
. Promoter site contains two specific
regions:
 Catabolite activator protein binding site (CAP site)
 RNA polymerase entry site, to which RNA
polymerase first becomes bound.
Structure of the Lac Operon
1. Regulatory gene (lac i) produces a repressor protein
2. A promoter site (P) for the binding of RNA
poly- merase
. Promoter site contains two specific
regions:
 Catabolite activator protein binding site (CAP site)
 RNA polymerase entry site, to which RNA
polymerase first becomes bound.

14. 3. An operator site (O), a regulatory protein called the lac
repressor protein binds to this site and blocks initiation of
transcription.
4. Three structural genes, Z, Y and A, that code for β-
galactosidase, galactoside permease and trans- acetylase
respectively, required for lactose metabolism.
3. An operator site (O), a regulatory protein called the lac
repressor protein binds to this site and blocks initiation of
transcription.
4. Three structural genes, Z, Y and A, that code for β-
galactosidase, galactoside permease and trans- acetylase
respectively, required for lactose metabolism.

15. Regulation of Lac Operon
Lac operon is regulated by following mechanism:
1.Regulation in absence of lactose and presence of glucose.
2. Regulation in presence of lactose and absence of glucose.
3. Regulation in presence of both glucose and lactose.
Regulation of Lac Operon
Lac operon is regulated by following mechanism:
1.Regulation in absence of lactose and presence of glucose.
2. Regulation in presence of lactose and absence of glucose.
3. Regulation in presence of both glucose and lactose.

16. Schematic diagram of lac operon showing its protein products.

17. Regulation of lac operon in presence of glucose and absence of
lactose.

18. Regulation of lac operon In presence of lactose and
absence of glucose.

19. Regulation Of Gene Expression In Eukaryotes

20.  Gene expression in eukaryotes starts at DNA level and
ends with an enzyme catalyzing a particular chemical
reaction, or with structural/metabolic protein.
 Signal molecules, environmental signals, and regulatory
proteins affect gene expression in eukaryotes.
 Gene expression in eukaryotes starts at DNA level and
ends with an enzyme catalyzing a particular chemical
reaction, or with structural/metabolic protein.
 Signal molecules, environmental signals, and regulatory
proteins affect gene expression in eukaryotes.

21. Gene expression in eukaryotes is controlled at five levels
1. DNA level (Replicational)
2. Transcriptional
3. Post-transcriptional
4. Translational
5. Post-translational.
Gene expression in eukaryotes is controlled at five levels
1. DNA level (Replicational)
2. Transcriptional
3. Post-transcriptional
4. Translational
5. Post-translational.

22. Five levels of regulation of expression of gene in eukaryotes.