The city is traversed by broad avenues from which runs a perfect labyrinth of narrow streets. Originally none of these streets were less than twenty feet wide, and some of the avenues leading up to the imposing gates of the palaces are even now a good two hundred feet in width. But the streets have all been encroached upon by the little temporary thatched booths of the petty retail dealers, so that, with the exception of the approaches to the palaces, the line is broken, the streets made tortuous, and only here and there a broad open spot indicates the original width of the thoroughfare. Originally every street was furnished with itd sewer—open in the smaller streets, while the avenues were drained by great covered sewers of stonework. Occasionally the proprietor of one of the little temporary booths would put a foundation under his structure, bridging over the sewer, until now the streets have in many cases become mere crooked alleys, and but for the bountiful rains, the excellent natural drainage, and the character of the soil, the mortality would be very great instead of being less than in ordinary American cities. No attempt is made towards street decoration, as that would attract the attention of thieves. The magnificent grounds of a nobleman, with their artificial lakes, flower gardens, water-worn pillars of ancient rock and quaintly twisted trees, may be enclosed by a row of tumble-down, smoke-begrimed servant-quarters that would never indicate the beauty to be found hidden within its forbidding exterior.
The third edition of Understanding DNA has been entirely revised and updated, and expanded to cover new advances in our understanding. It explains, step by step, how DNA forms specific structures, the nature of these structures and how they fundamentally affect the biological processes of transcription and replication.
Written in a clear, concise and lively fashion, Understanding DNA is essential reading for all molecular biology, biochemistry and genetics students, to newcomers to the field from other areas such as chemistry or physics, and even for seasoned researchers, who really want to understand DNA.Describes the basic units of DNA and how these form the double helix, and the various types of DNA double helixOutlines the methods used to study DNA structureContains over 130 illustrations, some in full color, as well as exercises and further readings to stimulate student comprehension