Chapter 1: Overview, DNA, Genes and Genome
- Page ID
- 27211
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Fig.1-1: Parent and offspring. Wolf’s Monkey. (Flickr-eclectic echos-CC:AND)
- Section 1.5: DNA Structure
- By 1878, a substance in the pus of wounded soldiers derived from cell nuclei (called nuclein) was shown to be composed of 5 bases (the familiar ones of DNA and RNA). The four bases known to make up DNA (as part of nucleotides) were thought to be connected through the phosphate groups in short repeating chains of four nucleotides. By the 1940s, we knew that DNA was a long polymer. Nevertheless, it was still considered too simple to account for genes.
- Section 1.6: Nucleic Acids - Structure and Function
- Alongside proteins, lipids and complex carbohydrates (polysaccharides), nucleic acids are one of the four major types of macromolecules that are essential for all known forms of life. The nucleic acids consists of two major macromolecules, Deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) that carry the genetic instructions for the development, functioning, growth and reproduction of all known organisms and viruses.
- Section 1.8: The Stuff of Genes
- That all eukaryotic cells contain a nucleus was understood by the late 19th century. By then, histological studies had shown that nuclei contained largely proteins and DNA. At around the same time, the notion that the nucleus contains genetic information was gaining traction. In 1910, Albrecht Kossel received the 1910 Nobel Prize in Physiology or Medicine for his discovery of the adenine, thymine, cytosine and guanine (the four DNA bases), as well as of uracil in RNA.
- Section 1.10: Genes and Genomes
- For many years, scientists wondered about the nature of the information that directed the activities of cells. What kind of molecules carried the information, and how was the information passed on from one generation to the next? Key experiments, done between the 1920s and the 1950s, established convincingly that this genetic information was carried by DNA. In 1953, with the elucidation of the structure of DNA, it was possible to begin investigating how this information is passed on, and is used
- Section 1.11: The Nuclear Genome
- The complete set of DNA within the nucleus of any organism is called its nuclear genome and is measured as the C-value in units of either the number of base pairs or picograms of DNA. There is a general correlation between the nuclear DNA content of a genome (i.e. the C-value) and the physical size or complexity of an organism.
- Section 1.12: Genes and Chromatin in Eukaryotes
- Chromosomes and chromatin are a uniquely eukaryotic association of DNA with more or less protein. Bacterial DNA (and prokaryotic DNA generally) is relatively ‘naked’ – not visibly associated with protein. The electron micrograph of an interphase cell (below) reveals that the chromatin can itself exist in various states of condensation.
Contributors
Dr. Todd Nickle and Isabelle Barrette-Ng (Mount Royal University) The content on this page is licensed under CC SA 3.0 licensing guidelines.
