Covers the flow of information from DNA to Protein synthesis, Transcription, Types of RNA, Genetic code, Protein Synthesis, Cell Function and cell reproduction

1. Genetic Control
(Protein Synthesis, Cell Function and cell reproduction)
EduCareer Management, Sukkur Institute of Health and
Science
Institute of Microbiology, Shah Abdul Latif University,
Khairpur
Dr. Anwar Hussain Phulpoto

2. Contents List
1. Gene control Protein synthesis
2. Genetic code
3. Transcription
4. Types of RNA
5. Translation
6. Control of gene function
7. Cell reproduction

3. Central Dogma of Molecular Genetics

4. DNA/RNA
A. Sugar (Ribose/Deoxy)
B. Nitrogenous base
C. Phosphate
C
B
A

6. Complementarity base pairing
I. A & T (Double bond) in DNA
II. A & U (Double bond) in RNA)
III. G & C (Triple bonds) in both
RNA
DNA

7. Nucleoside/Nucleotide

8. Polynucleotide chain

9. Transcription
Events during transcription
1. Recognition of Promoter area (DNA)
2. RNA Polymerase for transcription
3. Unwinding of DNA
4. Complementarily pairing to DNA
5. Polymerization and Chain termination sequence
determination
6. RNA separation and DNA rejoining

10. Transcription
• mRNA Synthesized has Introns and exons
• Introns are excised & Exons are spliced
• Methyl cap at 5 Prime and Poly A tail at 3
Prime.
• Methyl cap protect mRNA from the chain
degradation.

11. Transcription (Eukaryote)

12. Transcription (Prokaryote)

13. Genetic code/Codon/Triplet base Pair

14. RNA Types
RNA
Pre-
mRNA
SnRNA mRNA tRNA rRNA miRNA
1. Precursor mRNA (immature, introns+Exons)
2. Small nuclear RNA (Biocatalyst, splicing)
3. Messenger RNA (Carrier)
4. Transfer RNA (Protein synthesis)
5. Ribosomal RNA (A. Acids and anticodon specific to mRNA
6. MicroRNA (primer)

15. Precursor mRNA
• Pre-mRNA large immature mRNA. This
contains Introns and exons which are removed
by a proceess called Splicing and thus exons
are retained on the strand.

16. Small Nuclear RNA
• Small Nuclear (snRNA), Directs the splicing of
Pre-mRNA to form mature mRNA.

17. MicroRNA
• Single stranded RNA molecules of 21 to 23
nucleotides that can regulate the gene
transcription and Translation.
• This is non coding means not translated into
proteins.
• miRNAs are believed to play an important role in
the normal regulation of cell function, and
alterations in miRNA function have been
associated with diseases such as cancer and
heart disease.

18. Messenger RNA
• The long single stranded RNA molecule that are
suspended in the cytoplasm. mRNA contain
codons which are exactly complementary to the
code of triplets of DNA gene.
• Codons for the Aminoacids found in proteins
molecules.
• AUG (methionine) chain initiating codon (CI)
• UAA, UAG, UGA chain terminating codons (CT)

19. Transfer RNA
• Type of RNA plays an essential role in the
protein synthesis.
• Clover leaf structure of tRNA
• Transfer A. Acids to the protein chain
• Adenylic site for the poly peptide chain
• tRNA Carries specific code for specific codon
(triplet of base pair) called Anti-codon.

20. Ribosomal RNA
• rRNA (Ribosomal RNA), constitute 60% of ribosomes.
• Remainder ribosome is Protein (75 Types of proteins)
which are structural and functional (enzymes).
• Ribosome formation in nucleolus (the rRNA processed
in the nucleolus where it binds with “ribosomal
proteins” to form granular condensation products) are
primordial subunits of ribosome.
• Therefore, proteins are formed in the cytoplasm of the
cell but not in the cell nucleus, because the nucleus
does not contain mature ribosomes.

22. Translation

23. Translation
• Polyribosomes (mRNA attached to the cluster
of ribosomes)
• Many ribosomes attached to ER (Proteins-
containing secretory vesicles)
• Chemical steps in proteins synthesis (Energy,
Peptide bonding)

24. Control of Gene Function
Control of Gene
function
Gene Regulation
Enzyme
Regulation
Basically two methods by which the biochemical activities in the
cell are controlled: (1) genetic regulation, in which the degree of
activation of the genes and the formation of gene products are
themselves controlled, and (2) enzyme regulation, in which the
activity levels of already formed enzymes in the cell are controlled.

25. Gene Regulation
• Genetic regulation, or regulation of gene
expression, covers the entire process from
transcription of the genetic code in the
nucleus to the formation of proteins in the
cytoplasm. Regulation of gene expression
provides all living organisms with the ability to
respond to changes in their environment.

26. • TATA Box (also called Goldberg-Hogness box) is
sequence of DNA found in Core Promoter reegion.
The prokaryotic homolog of TATA box is called Pribno
box which has a shorter consensus sequence.
• Promoter: region of DNA that leads to the initiation
of transcription. Located near the transcription start
sites of gene, upstream on the DNA (5 prime of sense
strand). It can be about 100 to 1000 base pairs long

27. Mechanisms for Control of Transcription by the
Promoter
1. A promoter is frequently controlled by transcription
factors located elsewhere in the genome. That is,
the regulatory gene causes the formation of a
regulatory protein that in turn acts either as an
activator or a repressor of transcription.
2. Occasionally, many different promoters are
controlled at the same time by the same regulatory
protein. In some instances, the same regulatory
protein functions as an activator for one promoter
and as a repressor for another promoter.
•

28. Continue…..
3. Some proteins are controlled not at the starting point of
transcription on the DNA strand but farther along the strand.
Sometimes the control is not even at the DNA strand itself but
during the processing of the RNA molecules in the nucleus
before they are released into the cytoplasm; control may also
occur at the level of protein formation in the cytoplasm
during RNA translation by the ribosomes.
4. In nucleated cells, the nuclear DNA is packaged in specific
structural units, the chromosomes. Within each chromosome,
the DNA is wound around small proteins called histones,
which in turn are held tightly together in a compacted state by
still other proteins. As long as the DNA is in this compacted
state, it cannot function to form RNA.

30. Gene Regulation
TATAAAA

31. Enzyme Regulation

32. Feedback system (±)

33. Cell Division
• Life cycle of Cell (period from cell reproduction
to the next cell reproduction).
• Cell Reproduction Begins With Replication of
DNA The first step is replication (duplication)
of all DNA in the chromosomes. It is only after
this replication has occurred that mitosis can
take place.

34. Cell Division
• Chemical and Physical Events of DNA Replication.
1. DNA replication ( both complete strand)
2. DNA polymerase
3. Ligase (bonding)
4. Fragments (Okazaki)
5. Semi-conservative method
6. Coiling of DNA helixes

35. Cell Division
• DNA Repair, DNA “Proofreading,” and
“Mutation.”
• This repair process, which is achieved by the
same DNA polymerases and DNA ligases that
are used in replication, is referred to as DNA
proofreading.
• When a mistake is made, it is called a
mutation.

36. Cell Mitosis