By:
Dr. Mohammed Golam Rasul
What is DNA?
 DNA is a nucleic acid that contains the genetic
instructions used in the development and functioning
of all known living organisms and some viruses.
 DNA is made up of repeating molecules called
NUCLEOTIDE.
Why is DNA so Important?
DNA contains the genetic information used in the
development and functioning of all living things
and some viruses.
DNA is like blueprints, instructions, or a code
for making proteins.
DNA’s codes are converted/changed into
messages (mRNA) for ribosomes to read and
then make proteins.
Proteins do most of the hard work of keeping
us alive
The Structure of DNA
 Nucleotide monomers:
 Phosphate
 Pentose Sugar (C5) –
Deoxyribose Sugar
 Organic Nitrogen Base :




Cytosine (C)
Adenine (A)
Guanine (G)
Thymine (T)
Structure of DNA cont’
 Polynucleotide chain with
linkage via phosphates to
next sugar, with nitrogen
base away from backbone of
Phos-sugar-phos-sugar
 Dehydration synthesis
DNA is a Double-Helix
What is RNA?
 RNA is a biologically important type of molecule
that consists of a long chain of nucleotide units.
What is the job of RNA?
 To assist in the synthesis of proteins.
Ribonucleic Acid (RNA)
 Structure of RNA
 Nucleotide monomer





Phosphate
Pentose sugar = ribose (extra oxygen)
Nitrogenous base (A/G/C/U)
Single stranded
3 types (mRNA, tRNA, rRNA)
Types of RNA
1) messenger RNA (mRNA)carries instructions from the DNA
in the nucleus to the ribosome
Types of RNA
2) ribosomal RNA (rRNA)combines with proteins to
form the ribosome (proteins
made here)
3) transfer RNA (tRNA)transfers each amino acid
to the ribosome as it is
specified by coded
messages in mRNA during
the construction of a protein
Why is mRNA Important?
DNA is too big and CAN’T leave the nucleus…it
must send messages.
mRNA
is created by DNA in the nucleus
mRNA contains the messages from the DNA and
are sent to ribosomes for them to read the
instructions for making proteins
Why is mRNA Important?
DNA is too big and CAN’T leave the nucleus…it
must send messages.
mRNA is created by DNA in the nucleus
mRNA contains the messages from the DNA
and are sent to ribosomes for them to read the
instructions for making proteins
Chemical Structure of DNA vs RNA
Ribonucleotides have a 2’-OH
Deoxyribonucleotides have a 2’-H
Differences between DNA and RNA:
Structure
Bases- Purines
Bases Pyrimidines
Sugar
DNA
RNA
Double
Stranded
Adenine (A)
Guanine (G)
Cytosine (C)
Single Stranded
Thymine (T)
Deoxyribose
Uracil (U)
Ribose
Adenine (A)
Guanine (G)
Cytosine (C)