DNA Provides A Template For Replication & Transcription
المؤلف:
Peter J. Kennelly, Kathleen M. Botham, Owen P. McGuinness, Victor W. Rodwell, P. Anthony Weil
المصدر:
Harpers Illustrated Biochemistry
الجزء والصفحة:
32nd edition.p351-352
2025-09-06
494
The genetic information stored in the nucleotide sequence of DNA serves two purposes. It is the source of information for the synthesis of all protein molecules of the cell and organism, and it provides the information inherited by daughter cells or offspring. Both of these functions require that the DNA molecule serve as a template—in the first case for the transcription of the information into RNA and in the second case for the replication of the information into daughter DNA molecules.
When each strand of the double-stranded parental DNA molecule separates from its complement during replication, each independently serves as a template on which a new complementary strand is synthesized (Figure 1). The two newly formed double-stranded daughter DNA molecules, each containing one strand (but complementary rather than identical) from the parent double-stranded DNA molecule, are then sorted between the two daughter cells during mitosis (Figure 2). Each daughter cell contains DNA molecules with information identical to that which the parent possessed; yet, in each daughter cell, the DNA molecule of the parent cell has been only semiconserved.
Fig1. DNA synthesis maintains the sequence and structure of the original template DNA. The double-stranded structure of DNA and the template function of each old parental strand (orange) on which a new complementary daughter strand (blue) is synthesized.
Fig2. DNA replication is semiconservative. During a round of replication, each of the two strands of DNA is used as a template for synthesis of a new, complementary strand. The semiconservative nature of DNA replication has implications for the biochemical, cytogenetic, and epigenetic control of gene expression.
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