Ppt holds the deep description of central dogma of molecular biology,types of rna ,types of dna ,working of central dogma in body.

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S u b t i t l e
Central Dogma of Molecular Biology
Presented by : Aayushi Goel
Branch : M.Sc Chemistry
DNA
RNA

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S u b t i t l e
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What is central dogma?
The central dogma of molecular biology is a theory that explains
the flow of genetic information. It states that genetic information
flows in one direction, from DNA to RNA to protein.
The central dogma suggests that:
•DNA: Contains the information needed to make proteins
•RNA: Carries the information from DNA to the ribosomes
•Ribosomes: Translate mRNA to protein
•The process of DNA being copied to RNA is called
transcription. The process of RNA being used to produce
proteins is called translation.

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Types of RNA(ribonucleic acid)
• mRNA(messenger RNA)
• tRNA(transfer RNA)
• rRNA(ribosomal RNA)
• snRNA(small nuclear RNA)
Functions of RNA
The primary function of RNA is to create proteins via
translation.
Some RNAs, called microRNAs (miRNAs), can regulate gene
expression. They do this by binding to mRNA and preventing
it from being translated.
The rRNA ensures the proper alignment of the mRNA, tRNA,
and the ribosomes.

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Types of DNA
•A-DNA: It is right-handed DNA that contains a double helix.
•B-DNA: This DNA is a right-handed helix one and is a common
one.
•Z-DNA is a left-handed double helix DNA with a zigzag pattern.
Functions of DNA
Deoxyribonucleic acid (DNA) is a molecule that stores the genetic
instructions for an organism's development, functioning, and
reproduction.
DNA's four roles are: Replication, Encoding information,
Mutation/recombination, Gene expression.
DNA is responsible for:
•Carrying and transmitting hereditary materials or genetic
instructions from parents to offspring
•Ensuring that all living things pass on their genetic information
•Being essential for the synthesis of proteins

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Central Dogma Steps
The central dogma takes place in two different steps:
Transcription
Transcription is the process by which the
information is transferred from one strand of the
DNA to RNA by the enzyme RNA Polymerase. The
DNA strand which undergoes this process consists
of three parts namely promoter, structural gene, and
a terminator.
The DNA strand that synthesizes the RNA is called
the template strand and the other strand is called the
coding strand. The DNA-dependent RNA
polymerase binds to the promoter and catalyzes the
polymerization in the 3′ to 5′ direction.
As it approaches the terminator sequence, it
terminates and releases the newly synthesized RNA
strand. The newly released RNA strand further
undergoes post-transcriptional modification.
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Translation
• Translation is the process by which the RNA codes for
specific proteins. It is an active process which requires
energy. This energy is provided by the charged tRNA
molecules.
• Ribosomes initiate the translation process.
The ribosomes consist of a larger subunit and a smaller
subunit. The larger subunit, in turn, consists of two tRNA
molecules placed close enough so that peptide bond can be
formed at the expense of enough energy.
• The mRNA enters the smaller subunit which is then held by
the tRNA molecules of the complementary codon present in
the larger subunit. Thus, two codons are held by two tRNA
molecules placed close to each other and a peptide bond is
formed between them. As this process repeats, long
polypeptide chains of amino acids are synthesized. 6

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Genetic code
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• Genetic code contains the information of the protein
manufactured from RNA. There are basically three
nucleotides and four nitrogenous bases, which
collectively form a triplet codon that codes for one
amino acid. Therefore, the number of possible
amino acids range to 4 x 4 x 4 = 64 amino acids.
There are 20 naturally existing amino acids.
• The genetic code degenerates. This was explained
by the features of the genetic code, according to
which a few amino acids are coded by more than
one codon thus causing them to degenerate. Each
codon codes for only one specific amino acid and
the codes are universal irrespective of the type of
organism.
• Out of the 64 codons, 3 are stop codons which stop
the process of transcription and one of the codons is
an initiator codon i.e. AUG coding for Methionine.

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Watson-Crick Structure of DNA
•Watson and Crick presented a model for the DNA’s double-helix structure.
•A nucleotide polymer makes up the DNA molecule.
•A nitrogenous base, a five-carbon sugar (deoxyribose), and a phosphate group are
found in each nucleotide.
•There are two purines (adenine and guanine) and two pyrimidines in the DNA
(cytosine and thymine).
•Two strands of DNA make up a DNA molecule.
•Each strand is made up of nucleotides that are covalently linked by their phosphate
groups and deoxyribose sugars.
•The bases grow out of this backbone.
•Hydrogen bonds connect the bases of strands.
•Adenine is always linked with thymine, while cytosine is always linked with
guanine. 8

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Reverse central dogma
The reverse central dogma, also known as reverse
transcription or teminism, is the process of
synthesizing DNA from RNA.
In this process, information flows from RNA to
DNA, which then forms RNA again. The RNA is
then translated to form proteins.
Reverse transcription occurs in retroviruses, such as
HIV. Retroviruses have a phase in their life cycle
where their genomic RNA is converted back to DNA
by a virally-encoded enzyme called reverse
transcriptase.
As all viruses are not RNA viruses, thus the reverse
central dogma is only found in RNA viruses and not
others.
Reverse transcriptase of HIV. The nuclease function is
needed for the viral life cycle, but not for lab use.

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Importance of central dogma
The central dogma is important
because it:
•Provides a framework for understanding
genetic information flow
•Helps understand gene expression
•Helps understand the functioning of living
organisms
•Serves as a foundation for molecular
biology
•Has practical applications in fields such as
synthetic biology

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