Show An illustration to show replication of the leading and lagging strands of DNA. Leading Strand:
Lagging strand:
This page was last updated on 2021-07-21 DNA Structure DNA Replication Eukaryotic Chromosome Structure
Study Questions DNA Structure, Replication and Eukaryotic Chromatin Structure Overheads DNA Structure, Replication and Eukaryotic Chromatin Structure WWW Links Genetic Topics DNA replication is semi-conservative, one strand serves as the template for the second strand. Furthermore, DNA replication only occurs at a specific step in the cell cycle. The following table describes the cell cycle for a hypothetical cell with a 24 hr cycle.
DNA replication has two requirements that must be met:
Proteins of DNA ReplicationDNA exists in the nucleus as a condensed, compact structure. To prepare DNA for replication, a series of proteins aid in the unwinding and separation of the double-stranded DNA molecule. These proteins are required because DNA must be single-stranded before replication can proceed.
A General Model for DNA Replication
Genetics of E. coli DNA ReplicationMutants are powerful tools to study any biochemical process. But to be useful, the scienctist must be able to maintain mutant in a viable state. This poses a problem for mutants ofa essential processes such as DNA replication. If the mutated gene is re quired for DNA replication, it is obvious that the mutant will not last more than one generation. The use of conditional mutants has helped to solve this problem. Conditional mutants express their mutant phenotype only under restricted conditons. A popular form of conditional mutant is the temperature sensitive mutant. Temperature sensitive mutants only express their mutant phenotype at a temperature the organism normally does not confront. Many of these mutants are expressed at elevate d temperatures. Therefore the mutant will grow normally at the permissive temperature and express the mutant phenotype at the elevetated tempterature.The analysis of temperature-sensitive mutants of E. coli has defined a series of genes and their role in DNA synthesis. The following table list some of the genes and their role in E. coli DNA replication.
Copyright © 1997. Phillip McClean What helps to hold DNA strands apart while they are being replicated?A protein called Helicase breaks the Hydrogen Bonds of the two strands of DNA forming a Replication Fork. Proteins called Binding Proteins keep the two DNA strands apart preserving the Replication Fork.
What holds the strands of DNA apart?The two DNA strands are held together by hydrogen (H) bonds formed between the bases adenine and thymine to form the AT base pair and between the bases guanine and cytosine to form the GC base pair.
What holds DNA open during replication?The DNA helix is opened by a DNA polymerase molecule clamped on the leading strand, acting in concert with one or more DNA helicase molecules running along the strands in front of it. Helix opening is aided by cooperatively bound molecules of single-strand DNA-binding protein.
What keeps the strands separate during replication?First, a so-called initiator protein unwinds a short stretch of the DNA double helix. Then, a protein known as helicase attaches to and breaks apart the hydrogen bonds between the bases on the DNA strands, thereby pulling apart the two strands.
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