Dna Replication

Topics: DNA, DNA replication, Polymerase chain reaction Pages: 4 (916 words) Published: December 18, 2012
DNA Replication

What is DNA?
DNA is a nuclei acid. Nucleic acids are made of nucleotides (ribose/deoxyribose, phosphate group and nitrogenous bases). DNA has deoxyribose, is stable, and has the bases adenine, guanine, thymine and cytosine; it determines genetic information. DNA looks like ATP.

What is a DNA monomer?
A DNA monomer is a nucleotide. A nucleotide is formed of a 5 Carbon sugar, a phosphate and a nitrogenous base (adenine, thymine, cytosine and guanine). The bases that make up DNA code for genes.

How does a DNA monomer become a DNA polymer?
The backbone of DNA is held together by phosphodiester linkage. The nitrogenous bases from one strand are held to the other strand via hydrogen bonds. Polymers are formed from many nucleotides.

Describe DNA replication.
In order for asexually dividing cells to have identical DNA, the replication of DNA must occur. Old DNA is called parental DNA, and the new DNA is called daughter DNA. DNA replication requires enzymes, free nucleotides, and the DNA molecule. Steps:

(1) Topoisomerase unwinds the double helix.
(2) Helicase breaks the hydrogen bonds between the nitrogenous bases at the origins of replication. (3) SSBPs (Single Stranded Binding Protein) hold both strands of DNA open. (4) DNA primase produces RNA Primers which use complementary nucleotides to bind to the leading strand. (5) DNA polymerase adds additional bases to the RNA primer in order to elongate the daughter strand. (6) Ligase binds the sugar phosphate backbone together.

What is the difference between the leading strand and the lagging strand? In the leading strand DNA polymerase sits near the replication fork, moving as the fork foes, adding nucleotides one after the other, preserving the proper anti-parallel orientation. This sort of replication, since it involves one nucleotide being placed right after another in a series, is called continuous. In the leading strands, the nucleotides are added in the 5’ to 3’...
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