In 1953 D. Watson and Crick proposed a model structure of DNA, which is based on the following postulates.

Date: 2015-10-07; view: 432.

Subject: The structure of DNA and RNA. Purines and pyrimidines. Ribose and deoxyribose. Phosphoric acid residues.Structure of nucleotide monomers of nucleic acids. Types of nucleic acids. The chemical structure of nucleic acids. Primary and three-dimensional structure of DNA. Forms of messenger RNA (mRNA, rRNA, tRNA).

Laboratory work №9

Another plant of the same species, contained in low-temperature conditions, 15-20, gave the red flowers.

Objective: To study the structure and characteristics of DNA and RNA.

Necessary equipment: a porcelain mortar, centrifugal and simple tube, beaker of 100-150 ml, wooden sticks, water baths, glass powder, sodium chloride 5% solution of sodium hydroxide 0.4% diphenylamine reagent, distilled water, a piece of mammal spleen.

• DNA is a polymer composed of nucleotides joined by 3'-and 5'-phosphodiester bonds.

• Structure of DNA nucleotides follows the rules Chargaff.

• The DNA molecule has the structure of the double helix, as evidenced by x-ray diffraction patterns of strands of DNA, which was first obtained by M. Wilkins and R. Franklin.

• The structure of the polymer, as the acid-base titration of native (natural) DNA, stabilizes water bonds. Titration and heating native DNA stimulates noticeable changes in its physical properties, particularly bone viscosity, turning it into denatured form, and covalent bonds are not destroyed.