BIOL1020 Lecture Notes - Lecture 10: Operon, Gene Expression, Archaea
Document Summary
Bacterial diversity vastly surpasses that of archaea and eukaryotes. They thrive almost everywhere, including places too acidic, salty, cold, or hot for most other organisms. Most are microscopic, but what they lack in size they make up for in numbers. Bacteria are unicellular, and some species form colonies. Most bacterial cells are 0. 5-5 m, much smaller than the 10-100 m of many eukaryotic cells. Bacterial cells have a variety of shapes (the three most common shapes are spheres (cocci), rods (bacilli), and spiral. Mutualists - in our gut, nitrogen fixing rhizobia in legumes. Saprophytes - essential role in degradation of organic matter and recycling. Since bacteria have no nucleus, transcription and translation can occur in the same space. A single bacterial cell has 2500-6000 genes, depending on the size of its genome. Individual bacteria respond to environmental change by regulating their gene expression, they don"t express all their genes at the same time.
