Gene expression is an essential element to understand molecular Biology.Doctors should have clear understanding how gene is expressed and how gene expression is regulated. in this presentation 5 key concepts of regulation of gene expression (promter, enhancer, trancription factor, DNA methylation, splicing) have been discussed.

1. Welcome
Presenter
Dr. Md Imran Waheed
MS Anatomy

2. 5 key concepts
Regulation of Gene Expression

3. Process by which
DNA instructions are converted into
the functional product
Gene Expression
www.yourgenome.org › facts › what-is-gene-expression

4. DNA RNA
RNA Protein
Only
mRNA is translated into protein
Translation
Transcription
How gene is expressed?

5. DNA selectively transcribed
mRNA differentially processed
mRNA selectively translated
Proteins differentially modified
How gene expression is regulated?

6. Let’s explore the key concepts

7. Keyconcept-1

8. Promoter
DNA sequences that define
where transcription of a gene
by RNA polymerase begins
https://www.nature.com/scitable/definition/promoter-259/
Keyconcept-1

9. Promoter region
Keyconcept-1

10. 1. Why is promoter so important for gene transcription?
It is the site, where gene transcription initiates;
most of the regulatory elements act upon this region.
2. What are the regulators of promoter?
Enhancer, silencer, transcription factors etc.
Keyconcept-1

11. 3. What is TATA Box?
Conserved DNA sequence of promoter (TATAAA)
where RNA polymerase and transcription factors bind.
Keyconcept-1

12. Keyconcept-2

13. Key proteins
that initiate and regulate
the transcription of genes
Transcription factor
Keyconcept-2
https://www.nature.com/scitable/definition/transcription-factor-167

14. Keyconcept-2

15. 1. What is the most common form of gene regulation?
Regulation of transcription
2. What is the function of transcription factor in a nutshell?
Regulate turn on/off of the genes
Keyconcept-2

16. 3. How does transcription factor activate gene expression?
Unwinding nucleosome, releasing RNA polymerase,
preventing the formation of new nucleosome
4. What are two opposite ways it works?
Act as activator and act as suppressor
Keyconcept-2

17. Keyconcept-3

18. Enhancer
Regulatory DNA sequences
binding to transcription factors,
enhance the transcription
of an associated gene
https://www.nature.com/scitable/definition/enhancer-163/
Keyconcept-3

19. http://fig.cox.miami.edu/~cmallery/150/gene/mol_gen.htm
Enhancer
Keyconcept-3

20. 1.How does enhancer control rate of transcription?
By activating the promoter
2. Can same gene be expressed differently in different tissues
by different enhancers?
Yes
Keyconcept-3

21. 3. How does enhancer facilitate the binding of RNA polymerase?
Exposing the promoter by altering chromatin
4. What is silencer?
Negative enhancer
Keyconcept-3

22. Keyconcept-4

23. DNA methylation
An Epigenetic mechanism
addition of a methyl (CH3) group to DNA
often modifying the function of the genes
Keyconcept-4

24. https://www.epigentek.com/catalog/dna-methylation-c-75_21.html
Nucleosome
Keyconcept-4

25. 1. What is epigenetic mechanism?
DNA modifications without change in
the DNA sequence that can affect gene activity.
2. What are the cellular processes DNA methylation involved in?
Chromatin stability, genomic imprinting,
X-chromosome inactivation and carcinogenesis
Keyconcept-4

26. 3. How does methylation silence DNA?
By stabilizing nucleosome and
inhibiting the binding of transcription factors
Keyconcept-4

27. Keyconcept-5

28. The process by which
introns are excised out
exons are joined together
to generate mature mRNA
Splicing Keyconcept-5

29. https://www.ncbi.nlm.nih.gov/Class/MLACourse/Modules
/MolBioReview/alternative_splicing.html
Intron
Spliced out
Keyconcept-5

30. 1. How gene expression is regulated by splicing?
It enables different cells to use the same gene
to make proteins specific for the cell type.
2. What is spliceosome?
Complexes of snRNA and protein
3. What are splicing isoforms?
Proteins derived from same gene
Keyconcept-5

31. And finally…
Please keep in mind…

32. Mutation and deletion
of promoter, enhancer, silencer, and
defective
DNA methylation and splicing are
related with many clinical disorders