Chromatin Is The Chromosomal Material Extracted From Nuclei Of Cells Of Eukaryotic Organisms

Chromatin consists of very long double-stranded DNA molecules and a nearly equal mass of rather small basic proteins termed histones as well as a smaller amount of nonhistone proteins (most of which are acidic and

*So far as is possible, the discussion in this chapter and in Chapters 37, 38, and 39 will pertain to mammalian organisms, which are, of course, among the higher eukaryotes. At times it will be necessary to refer to observations in prokaryotic organisms such as bacteria and viruses, but in such cases the information will be of a kind that can be extrapolated to mammalian organisms.

larger than histones) and a small quantity of RNA. The nonhistone proteins include enzymes involved in DNA replication, such as DNA topoisomerases. Also included are proteins involved in transcription, such as the RNA polymerase complex. The double-stranded DNA helix in each chromosome has a length that is thousands of times the diameter of the cell nucleus. One purpose of the molecules that comprise chro-matin, particularly the histones, is to condense the DNA. Electron microscopic studies of chromatin have demonstrated dense spherical particles called nucleo-somes, which are approximately 10 nm in diameter and connected by DNA filaments (Figure 36-1). Nu-cleosomes are composed of DNA wound around a collection of histone molecules.

Diabetes 2

Diabetes 2

Diabetes is a disease that affects the way your body uses food. Normally, your body converts sugars, starches and other foods into a form of sugar called glucose. Your body uses glucose for fuel. The cells receive the glucose through the bloodstream. They then use insulin a hormone made by the pancreas to absorb the glucose, convert it into energy, and either use it or store it for later use. Learn more...

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