What Monomers Make Up Dna

DNA Structure Activity

Problem x: Review of the Features of the Watson-Crick Model for DNA Structure

Components of DNA

Deoxyribonucleic acid is a polymer. The monomer units of Dna are nucleotides, and the polymer is known as a "polynucleotide." Each nucleotide consists of a 5-carbon sugar (deoxyribose), a nitrogen containing base attached to the carbohydrate, and a phosphate group. There are four different types of nucleotides plant in Dna, differing just in the nitrogenous base. The iv nucleotides are given one letter of the alphabet abbreviations as shorthand for the iv bases.

A is for adenine
G is for guanine
C is for cytosine
T is for thymine

DNA Bases

Adenine and guanine are purines. Purines are the larger of the two types of bases found in DNA. The nine atoms that make up the fused rings (5 carbon, 4 nitrogen) are numbered i-9. All ring atoms lie in the aforementioned aeroplane. Cytosine and thymine are pyrimidines. The 6 atoms (4 carbon, 2 nitrogen) are numbered 1-half-dozen. Like purines, all pyrimidine band atoms prevarication in the same plane.

Deoxyribose Sugar

The deoxyribose carbohydrate of the Dna backbone has v carbons and 3 oxygens. The carbon atoms are numbered 1', 2', 3', four', and five' to distinguish from the numbering of the atoms of the purine and pyrmidine rings. The hydroxyl groups on the 5'- and 3'- carbons link to the phosphate groups to form the DNA courage. Deoxyribose lacks an hydroxyl group at the ii'-position when compared to ribose, the carbohydrate component of RNA.

Nucleosides and Nucleotides

A nucleoside is ane of the 4 Deoxyribonucleic acid bases covalently attached to the C1' position of a sugar. The sugar in deoxynucleosides is two'-deoxyribose. The sugar in ribonucleosides is ribose. Nucleosides differ from nucleotides in that they lack phosphate groups. The four dissimilar nucleosides of Dna are deoxyadenosine (dA), deoxyguanosine (dG), deoxycytosine (dC), and (deoxy)thymidine (dT, or T). In dA and dG, there is an "Due north-glycoside" bond betwixt the sugar C1' and N9 of the purine. A nucleotide is a nucleoside with one or more than phosphate groups covalently fastened to the 3'- and/or 5'-hydroxyl group(due south).

DNA Backbone

The Deoxyribonucleic acid backbone is a polymer with an alternating sugar-phosphate sequence. The deoxyribose sugars are joined at both the 3'-hydroxyl and 5'-hydroxyl groups to phosphate groups in ester links, too known equally "phosphodiester" bonds.

Deoxyribonucleic acid Double Helix

DNA is a commonly double stranded macromolecule. Ii polynucleotide chains, held together by weak thermodynamic forces, form a DNA molecule.

Features of the Deoxyribonucleic acid Double Helix

2 Deoxyribonucleic acid strands form a helical screw, winding around a helix axis in a right-handed spiral.
The two polynucleotide chains run in opposite directions.
The carbohydrate-phosphate backbones of the two Deoxyribonucleic acid strands current of air around the helix axis like the railing of a sprial staircase.
The bases of the individual nucleotides are on the inside of the helix, stacked on top of each other like the steps of a screw staircase.

Base Pairs

Within the Deoxyribonucleic acid double helix, A forms ii hydrogen bonds with T on the opposite strand, and Thou forms iii hyrdorgen bonds with C on the opposite strand. dA-dT and dG-dC base of operations pairs are the same length, and occupy the same space inside a Dna double helix. Therefore the DNA molecule has a uniform diameter. dA-dT and dG-dC base of operations pairs can occur in any order within Deoxyribonucleic acid molecules

DNA Helix Axis

The helix axis is most credible from a view directly downward the axis. The sugar-phosphate backbone is on the outside of the helix where the polar phosphate groups (red and yellow atoms) can interact with the polar environment. The nitrogen (bluish atoms) containing bases are within, stacking perpendicular to the helix axis.