DNA Structure and History

Flashcards about DNA structure and history.

Nuclein (DNA)

An acidic, phosphorus-rich substance discovered in 1869 by Johann Friedrich Miescher, now known as the repository of our genes.

Swiss biochemist Johann Friedrich

• studied nuclei of large nuclei with minimal amounts of cytoplasm.

• In 1869 he discovered an acidic, phosphorus rich substance named nuclein.

• Correctly believed this to be the cells hereditary matter. We now call this substance DNA.

DNA Components

The basic components of DNA are sugar, phosphate groups, and organic rings.

DNA Molecule

A long threadlike molecule with a uniform diameter of 2 nm; most human cells have 46 molecules of DNA totaling 2 m in length.

Nucleic Acids

Polymers of nucleotides consisting of a sugar, a phosphate group, and a single- or double-ringed nitrogenous base.

Pyrimidines

Cytosine (C) and Thymine (T).

Purines

Adenine (A) and Guanine (G).

Base Pairs

A-T and C-G, which reflects the fact that one strand governs the base sequence of the other.

Double Helix

The structure of DNA, resembles a spiral staircase, with each sidepiece is a backbone composed of phosphate groups alternating with the sugar deoxyribose.

Rosalind Franklin

Determined DNA had a repetitious helical structure with sugar and phosphate on the outside of the helix using X-ray diffraction.

Watson and Crick

Shared the Nobel Prize for Physiology or Medicine in 1962 for determining the double-helical structure of DNA.