How dna replication occur?

Question

Dna replication occur when it is in double
helical before having this it is highly
coiled having1.75 turns then how dna get their doble helical str. for replication

Answer 1

When DNA replication takes place weaker hydrogen bonds that join complementary bonds together become broken. The two different sides of the DNA ladder start to unravel. The parent strands, however, stay joined. The parent strands that remain become molds to nucleotides, that attach themselves to complementary bases. Polymerases fuse those free nucleotides into the DNA strand.



Step 1: A special enzyme (helicase) "unzips" the double helix that is the DNA and Single Strand Binding Proteins stabilise the structure.

Step 2: A primer with a short DNA sequence complementary to a region on the parental strand is added by a primase to allow replication to occur.

Step 3: Another enzyme (DNA polymerase) combines free-floating deoxyribonucleosides triphosphate to their corresponding nucleotides that are attached to the DNA strand, attaching the free nucleotide to the 3' OH tail of the previous section, forming a complementary strand of DNA from the 5' to 3' direction.



Really it's that easy. When it's finished, there are two identical strands of DNA, assuming no mutations occurred...

Answer 2

­DNA carries the information for making all of the cell's proteins. These pro­teins implement all of the functions of a living organism and determine the organism'­s characteristics. When the cell reproduces, it has to pass all of this information on to the daughter cells.



Before a cell can reproduce, it must first replicate, or make a copy of, its DNA. Where DNA replication occurs depends upon whether the cells is a prokaryote or a eukaryote (see the RNA sidebar on the previous page for more about the types of cells). DNA replication occurs in the cytoplasm of prokaryotes and in the nucleus of eukaryotes. Regardless of where DNA replication occurs, the basic process is the same.

Answer 3

DNA is required as a template for producing all of the bodies proteins. A full set of chromosomes (DNA) is necessary in each cell in the body (except germ cells, but that is a different issue altogether). Each time a new cell is made (ie. during tissue turnover or growth) the DNA needs to replicate so that each new cell has a full set of chromosomes.

DNA replication is the process of copying a double-stranded deoxyribonucleic acid (DNA) molecule, a process essential in all known life forms. The general mechanisms of DNA replication are different in prokaryotic and eukaryotic organisms.



As each DNA strand holds the same genetic information, both strands can serve as templates for the reproduction of the opposite strand. The template strand is preserved in its entirety and the new strand is assembled from nucleotides. This process is called semi conservative replication. The resulting double-stranded DNA molecules are identical; proofreading and error-checking mechanisms exist to ensure extremely high fidelity.

In a cell, DNA replication must happen before cell division. Prokaryotes replicate their DNA throughout the interval between cell divisions. In eukaryotes, timings are highly regulated and this occurs during the S phase of the cell cycle, preceding mitosis or meiosis I.

Answer 4

dna replication is a semi conservative process i.e. only one of the stands get utilized into the formation of dna.... and the other remains unaltered .....