Билингвальный урок по теме Нуклеиновые кислоты

Topic: THE NUCLEIC ACIDS. DNA

Friedrich Miescher in 1869 isolated what he called nuclein from the nuclei of pus (contains dead skin cells, bacteria and white blood cells) cells. Nuclein was shown to have acidic properties; hence (for this reason) it became called nucleic acid.

Two types of nucleic acid are found -Deoxyribonucleic acid (DNA), Ribonucleic acid (RNA).

The distribution of nucleic acids in the eukaryotic cell

DNA is found in the nucleus with small amounts in mitochondria and chloroplasts. RNA is found throughout the cell. DNA as genetic material can be used as circumstantial evidence. Present in all cells and virtually restricted to the nucleus. The amount of DNA in somatic cells (body cells) of any given species is constant (like the number of chromosomes). The DNA content of gametes (sex cells) is half that of somatic cells.
In cases of polyploidy (multiple sets of chromosomes) the DNA content increases by a proportional factor. The mutagenic effect of UV light peaks at 253.7nm. The peak for the absorption of UV light by DNA

NUCLEIC ACID STRUCTURE

Nucleic acids are polynucleotides. Their building blocks are nucleotides.

• a nitrogen-containing "base" - either a pyrimidine (one ring) or purine (two rings).Examples: Adenine, Guanine, Cytosine, Thymine, Uracil

• a 5-carbon sugar - ribose or deoxyribose

• a phosphate group

DNA IS MADE OF TWO STRANDS OF POLYNUCLEOTIDE

The sister strands of the DNA molecule run in opposite directions (antiparallel). They are joined by the bases

Each base is paired with a specific partner: A is always paired with T ,G is always paired with C