• DNA is made up of repeating units called nucleotides.
• Each nucleotide is composed of:
• A five-carbon sugar (deoxyribose).
• Phosphate molecule.
• Nitrogenous base, four types are available i.e,
? Adenine - (A)
? Guanine - (G)
? Cytosine - (C)
? Thymine - (T)
• The bases are represented by their initials as A, G, C and T respectively.
• The sugar alternates with the phosphate, and the two form the backbone of the strands.
• The bases combine in a specific manner, such that Adenine pairs with Thymine and Guanine pairs with Cytosine.
• The bases are held together by hydrogen bonds. A gene is the basic unit of inheritance consisting of a number of bases in linear sequence on the DNA.
• Genes exert their effect through protein synthesis.
• The sequence of bases that make up a gene determine the arrangement of amino acids to make a particular protein.
• The proteins manufactured are used to make cellular structures as well as hormones and enzymes.
• The types of proteins an organism manufactures determines its characteristics.
• For example, albinism is due to failure of the cells of an organism to synthesise the enzyme tyrosine required for the formation of the pigment melanin.
Wilfykil answered the question on February 28, 2019 at 10:29
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