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Chapter-24 DNA: Structure and Replication

BOOK TITLE: Textbook of Biochemistry for Dental Students

Author
1. Vasudevan DM
2. S Sreekumari
3. Vaidyanathan Kannan
ISBN
9789350254882
DOI
10.5005/jp/books/11333_24
Edition
2/e
Publishing Year
2011
Pages
6
Author Affiliations
1. Faculty of Medicine, Amrita Vishwa Vidyapeetham, (Amrita University), Kochi, Kerala, Formerly Principal, College of Medicine, Amrita, Kerala; Formerly, Dean, Sikkim Manipal Institute of Medical Sciences, Gangtok, Sikkim, Amrita Vishwa Vidyapeetham (Deemed University), Cochin, Kerala, E-mail: dmvasudevan@aims.amrita.edu, PG Programs and Research College of Medicine, Amrita Institute of Medical Sciences, Kochi, Kerala, India, College of Medicine, Amrita Institute of Medical Sciences, Kochi, Kerala, India; Sikkim Manipal Institute of Medical Sciences, Gangtok, Sikkim, India
2. Jubilee Mission Medical College, Trissur, Kerala, Sree Gokulam Medical College and Research Foundation, Thiruvananthapuram, Kerala, India, Jubilee Mission Medical College and Research Institute, Thrissur, Kerala, India, Government Medical College, Thrissur and Thiruvananthapuram, Kerala, India; Sree Gokulam Medical College and Research Foundation, Thiruvananthapuram, Kerala, India; Jubilee Mission Medical College and Research Institute, Thrissur, Kerala, India
3. Amrita Institute of Medical Sciences, Kochi, Kerala, India, Pushpagiri Institute of Medical Sciences and Research Centre, Thiruvalla, Kerala, India, Believers Church Medical College and Hospital, Thiruvalla, Kerala, India
Chapter keywords

Abstract

Nucleotides are combined together by phosphodiester linkages to produce the lengthy DNA molecule. Base sequence in DNA is written from 5\' to 3\' end. Watson-Crick model of DNA consists of: (a) right handed double helix, (b) base pairing of A with T and G with C, (c) hydrogen bonding between the strands, (d) the two strands run in antiparallel. DNA is supercoiled and condensed thousands of times to produce chromosome. Segment of gene coding for proteins are called exons (expressed regions), and intervening areas are introns. Replication is semi-conservative in nature. Each strand serves as a template or mould, over which a new complementary strand is synthesized. Base pairing rule is always maintained. DNA polymerization is taking place from 5\' to 3\' direction; i.e. the template is read in the 3\' to 5\' direction. DNA polymerase alpha is the major enzyme in mammalian cells. RNA primer is required for starting the DNA synthesis. In the lagging strand, polymerization is taking place in small pieces, these are called Okazaki pieces.

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