BIOLOGY 3 Lecture Notes - Lecture 30: Genetic Recombination, Pilus, Neisseria
Document Summary
Antonie van leeuwenhoek (dutch naturalist, 17th century) discovered bacteria while examining scrapings from his teeth the organisms leeuwenhoek observed were thought to arise spontaneously from inanimate matter. ~ 1850, pasteur devised an experiment showing that the bacteria present in air contaminated the media. A single spoonful of soil contains 1010 prokaryotes; these are the most numerous life forms. Prokaryote means before a nucleus and their cells lack a eukaryotic nucleus. Prokaryotic fossils date back to 3. 5 billion years ago fossils indicate prokaryotes were alone on earth for 2 billion years - they adapted & evolved very diverse metabolic capabilities. Prokaryotes range in size from 1 10 m in length and from 0. 7 1. 5 m in width. Most prokaryotes have a rigid cell wall (made from peptidoglycan in bacteria) outside the plasma membrane that keeps the cell from bursting or collapsing due to osmotic changes.
