Title: Gene regulation:
1Lecture 37
-
- Gene regulation
- Control of gene expression.
- (Prokaryotic cells)
2Regulation of Gene Expression.
3Regulation depends on the type of metabolism.
4Turn-on a Catabolic Pathway.
5Turn-off a Anabolic Pathway.
6Transcription is regulated by binding of a
REGULATOR to a OPERATOR.
7Gene regulation in prokaryotes 1. By positive
control a. with induction of gene expression b.
with repression of gene expression 2. By negative
control a. with induction of gene expression b.
with repression of gene expression.
8REGULATORS are DNA-binding, Allosteric proteins.
9(Prokaryotic) Operon.
Structural genes
P
O
A
B
C
R
DNA
RNA
active regulator
protein
E1
E2
E3
inactive regulator
Function
10Example 1 Regulation of the Tryptophan Operon by
availability of tryptophan.
11Tryptophan operon
Without tryptophan
polymerase
Structural genes
P
O
Z
Y
A
R
inactive repressor
Function
With tryptophan
P
O
Z
Y
A
R
active repressor
Tryptophan
inactive repressor
12Example 1 Regulation of the Lactose Operon by
availability of lactose.
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14Lactose operon
Without lactose
P
O
Z
Y
A
R
active repressor
polymerase
With lactose
Structural genes
P
O
Z
Y
A
R
inactive repressor
active repressor
Function
Lactose
15(Prokaryotic) Operon.
Structural genes
P
O
A
B
C
R
DNA
RNA
active regulator
protein
E1
E2
E3
inactive regulator
Function
16Gene regulation in prokaryotes 1. By positive
control a. with induction of gene expression b.
with repression of gene expression 2. By negative
control a. with induction of gene expression b.
with repression of gene expression.
17Tryptophan operon
Without tryptophan
polymerase
Structural genes
P
O
Z
Y
A
R
inactive regulator
Function
With tryptophan
P
O
Z
Y
A
R
active repressor
Tryptophan
inactive regulator
18Lactose operon
Without lactose
P
O
Z
Y
A
R
active regulator
polymerase
With lactose
Structural genes
P
O
Z
Y
A
R
inactive repressor
active regulator
Function
Lactose
19Example 3 Lactose Operon. Breakdown of lactose
more difficult than breakdown of glucose
20Example 3 Lactose Operon. Lactose Regulator and
CAP Regulator.
21cAMP structure.
22Example 3 Lactose Operon has two Operators
23Example 3 Lactose Operon. Lactose Regulator and
CAP Regulator Negative control and
Positive control with induction.
24Example 3 Lactose Operon. Lactose Regulator and
CAP Regulator Negative control and
Positive control with induction.
25Fig. 14-6, p. 312
26Example 3 Lactose Operon.
GLU LAC Transcription
NO NO
Yes NO
NO YES
YES YES
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28Glucose low, cAMP high promotor activated
Glucose high, cAMP low, promotor not activated
29Glucose low Lactose not present
Glucose low Lactose present
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31Prokaryotic Regulator - Operator Transcription
Factor - Response Element.
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34Transcription Factors have a DNA-Binding Domain.
35Prokaryotic Regulator - Operator Transcription
Factor - Response Element.
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38Transcription Factors have a DNA-Binding Domain.
39Three DNA-Binding Domains Helix-turn-Helix.
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42Three DNA-Binding Domains Zinc-finger.
43Zinc finger.
44Transcription Factor with 3 Zn-finger domains
bound to DNA.
45Three DNA-Binding Domains Leucine zipper.
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49(Helix-turn-helix)
50Lecture 38
-
- Gene regulation
- Eukaryotic cells,
- Transcription factors.
51Regulation of gene expression eukaryotes
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53Organization of Eukaryotic Gene
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56Regulation of gene transcription activation of a
TF by phosphorylation..
57Regulation of gene transcription activation of a
TF by removal of inhibitor..
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59Eu-chromatin and Hetero-chromatin
60Common Bases
Methylated bases
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