Biology 2nd year

1. Nucleic Acid
Dr. Aarab Khan Lund

2. Nucleic Acids
• Nucleic acids are molecules that store information for cellular
growth and reproduction
• There are two types of nucleic acids:
- deoxyribonucleic acid (DNA)
-ribonucleic acid (RNA)
• A nucleotide consists of a nitrogenous base, a pentose sugar
and a phosphate group:

3. Nitrogen Bases

5. Pentose Sugars
• There are two related pentose sugars:
- RNA contains ribose
- DNA contains deoxyribose
• The sugars have their carbon atoms numbered with primes
to distinguish them from the nitrogen bases

6. Nucleosides and Nucleotides
• Nitrogen base+Pentose Sugar =Nucleoside
• Nitrogen base+Pentose Sugar+Phosphate group= Nucleotide

7. Types of Nucleotides
• Mononucleotide
• Dinucleotide
• Polynucleotide

8. DNA (Hereditary material)
• Griffith
• None virulent bacteria->Virulent bacteria.
• Hershy and Chase
• Bacteriophage-DNA-Host-more phages.
• All nucleotides of DNA, phosphate and
deoxyribose sugars are always common but
nitrogenous bases are different.
• Each DNA has specific sequences of nitrogenous
bases. It encodes vaste amount of information

11. Gene Expression
• Transcription and Translation.

15. Continue
• Initiation of protein synthesis occurs when a mRNA attaches to
a ribosome.