Molecular Genetics

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1. DNA Nucleotide

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Nucleotides consist of three parts --- a pentose sugar, a nitrogen-containing base, and a phosphate group. A pentose sugar is a five-sided sugar. Deoxyribose has a hydrogen atom attached to its #2 carbon atom (designated 2'), and ribose has a hydroxyl group atom there. Deoxyribose-containing nucleotides are the monomers of DNA

RNA Nucleotide

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The left picture shows the nucleotide unit of RNA. Nucleotides differ from nucleosides in that they have phosphate groups. Nucleotides can exist in the mono-, di-, or tri-phosphorylated forms. The most common site of phosphorylation of nucleotides found in cells is the hydroxyl group attached to the 5'-carbon of the ribose. Nucleotide units line up forming the backbone of RNA / DNA.

1A. Typical DNA Molecule

DNA is a complex molecule that is found in all living organisms. Constructing DNA models is a great way to learn about DNA structure, function and replication. DNA contains the genetic information for the reproduction of life. Its structure is that of a twisted double helix that is composed of long strands of alternating sugars and phosphate groups, as well as nitrogenous bases (adenine, thymine, guanine and cytosine). The basic unit of structure for a DNA molecule is the nucleotide. A nucleotide is composed of a phosphate, a deoxyribose sugar molecule, and a nitrogen-containing base (A, T, C, or G). The instructions carried on DNA are used to make proteins from amino acids in the cytoplasm. RNA must first make a copy of DNA in the nucleus before the proteins can be built by ribosomes in the cytoplasm.

1B.Typical RNA Molecule

RNA has larger grooves, which makes it vulnerable to attacks by enzymes. B form defines the helix geometry of DNA. The body destroys enzymes that cling to DNA. It can be though damaged by exposure to ultra violet rays.

General Comparison

Though both DNA and RNA consist of repetitive units of...
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