DNA structure and replication

Nucleotides

Made up of three components: phosphate group, pentose suga and a nitrogenous base.
There are four possible bases: adenine, guanine, cytosine and thymine.
Cytosine and thymine are pyrimadines
Adenime and guanine are purines.
There is a phosphodiester bond between the phosphate group and the pentose sugar.

Polynucleotide

The polynucleotide has a phosphate and sugar back bone.
The nucleotides join in a condensation reaction where a phosphodiester bond forms between the sugar on the first nucleotide and the phosphate group on the next nucleotide.

Double helix formation

DNA has a double helix structure. DNA stands for deoxyribose nucleic acid. A polynucleotide forms in a condensation reaction by the pentode sugar and the next phosphate group joining with a phosphodiester bond. Another polynucleotide runs in the opposite direction (antiparallel). The complementary bases line up and two hydrogen bonds form between A and T, and three hydrogen bonds form between G and C. Because the chains are antiparallel and the bases are different sizes, the chains twist, forming a helix. Thymine and cytosine are pyrimidines, and adenine and guanine are purines.

Replication of DNA

It is a semi conservative process.
DNA polymerase brings bases together and hydrogen bonds form.
DNA ligament sticks the back bone together.
DNA helicase unzips the strand.

	Creado por Chloe Drewery hace alrededor de 7 años

A level (Chapter 21 - Manipulating Genomes) Biology Apunte sobre Manipulating Genomes, creado por Chloe Drewery el 07/09/2017.