3. • Cell is regarded as a basic functional unit of life.
• It has many micro and macro molecules to carry
out activities which make life.
• One of the most important macro molecule of the
cell is DNA which is found in the nucleus of the
eukaryotic cells.
• It is regarded as a master molecule of the body
and is double helical in shape.
STRUCTURE OF DNA
4. • DNA is a polymer
• The monomer units of DNA are nucleotides and the polymer is
known as polynucleotide.
• Each nucleotide consists of : 5 carbon suger, a nitrogen
containing base attached to sugar, a phosphate group.
• Nitrogen bases : Purines and pyrimidines
• Purines-adenosine and guanine
• Pyrimidines- cytosine and thiamine or uracil (RNA)
• Purines are larger than pyrimidines
STRUCTURE OF DNA
5. NUCLEOSIDES NUCLEOTIDES
• Comprises of one of 4 DNA bases covalently
attached to the C1 position of deoxyribose sugar
• It is a nucleoside + phosphate group which is
covalently attached to the 3 or 5 hydroxyl group
• They lack phosphate group • They have phosphate group
• 4 different nucleosides are deoxy adenosine
• Deoxyguanosine
• Deoxy cytosine
• Deoxy thymidine
• -
6.
7. DNA
• Double helical and H2 bonding.
• Made of two strands of nucleotides joined by H2 bonds
• A=T; C≡G which is called complementary base pairing
• Purines are larger than pyrimidines
• Alternating sugar and phosphate forms DNA and backbone of DNA
