The presentation covers the basic information of the genetic codes, importance of nucleic acids and central dogma

1. Nucleic Acids and The Central
Dogma Theory

2. Contents
 What are nucleic acids?
 Function of nucleic acids
 Central Dogma Theory
 Protein Synthesis
 Transcription and Translation Process Explained
 Differences between Eukaryotes and Prokaryotes
 Take home message
 References

3. What are Nucleic Acids?
 The transfer media for organisms to pass information from one generation to
the other.
 There are two main types of nucleic acids involved known as RNA and DNA
 Nucleotides act as the building blocks for DNA & RNA
 These nucleic acids are composed of nucleotide monomers, these are formed of
three main parts.
 A nitrogenous base
 Five carbon sugar
 Phosphate group

4. • The basic structure of a nucleotide molecule is on
the diagram on the right side.
• For the nucleotides the nitrogenous bases will
vary, these could be either a purine (2 ringed
structure) or a pyrimidine (1 ringed structure)
 Adenine
 Thymine
 Guanine
 Cytosine
 Uracil (RNA only)
• The adenine and guanine molecules fall into the
purines while cytosine, thymine and uracil fall into
pyrimidine.
• The base pairing rules are followed by the bases,
where purine can form a hydrogen bond with
pyrimidine and vise versa.
• Adenine binds with thymine in DNA and is
replaced by uracil in the RNA.
• Cytosine binds with guanine.
• These base pairings ensure that the genetic code
remains universal in all types of cells.
Figure 1: Nucleic Acid Structure
(Cooper & Hausman 2009)

5. Figure 2: Nitrogenous Bases (Michael W. Davidson 2015)

6. Function of Nucleic Acids
 Nucleic acids are responsible for the actions to pass on information
from generation to generations.
 These are the hereditary determinants of the living organisms.
 These nucleic acids pass on the genetic information in a process
known as protein synthesis where proteins are made, this is also
stated in the central dogma theory.

7. Central Dogma theory
 The central dogma theory states that the genetic information is
transferred from DNA to DNA replication during its transmission
from generation to generation and DNA to RNA to protein during
its phenotypic expression in an organism.
 The DNA contains all necessary information that is needed to make
all proteins, RNA acts as a messenger that carries the information
towards the organelles known as ribosomes which makes the
proteins.

8. Figure 3: Central Dogma Theory (Cooper 2000)

9. Protein synthesis
 Protein synthesis is the process where proteins are made, this
process is in which central dogma theory is explained briefly.
 Transcription is the initial process of this protein making process,
where the information stored on the DNA is copied onto the RNA
as a single strand of a double helix.
 Translation is the later stage where the amino acids are formed and
transported around using the tRNA

10. Transcription in Protein Synthesis
 Transcription is the process in which the information from the DNA
is copied onto the RNA.
 Messenger RNA creates a sequence complementary to the DNA
strand.
 RNA polymerase enzyme is able to bring the complementary bases
matching to the DNA.
 Once this strand is complementary synthesized, it leaves the nucleus

11. Figure 4: Transcription Process (Cooper & Hausman 2009)

12. Translation in Protein Synthesis
 This is the final step in which the DNA converts to the protein.
 The nucleotide sequence in the mRNA is read in triplets also
known as codons.
 Each codon represents one amino acid, the tRNA and rRNA in
this process carries the amino acids and the ribosomes make
the proteins in a long polypeptide chain.

13. Figure 5: Translation Process (Cooper & Hausman 2009)

14.  These amino acids formed by the translation, where 20 different types of amino
acids are formed.
 These are responsible for
o Synthesizing and repairing the DNA
o Transporting the material
o Catalyzing the chemical reactions
 Proteins have different functions inside the body and can form different
structures as well.

15.  Primary Structure – Linear sequence of amino acids joined together by peptide
bonds.
 Secondary Structure – More complicated structures where they act as backbones
such as the alpha helix and beta pleated structure.
 Tertiary Structure – The three dimensional structure of proteins
 Quaternary Structure – The structure of spatial arrangement of multiple subunits.

16. EUKARYOTES PROKARYOTES
Uses 80s ribosomes Uses 70s ribosomes
Protein synthesis occurs in the
cytoplasm
Protein synthesis occurs before
transcription of the mRNA
molecule
Genes contain introns No introns present
9 initiating factors are involved
here
Only two initiation factors involved
Differences in Prokaryotic and Eukaryotic Protein Synthesis
Table 1: Eukaryotes vs Prokaryotes