KINGDOM MONERA. Bacterial Cell Shape 8/22/2010. The Prokaryotes: Archaebacteria and Eubacteria

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1 KINGDOM MONERA The Prokaryotes: Archaebacteria and Eubacteria Bacteria are the most organisms living on the Earth. (i.e. 10mL of soil contains 1 x bacteria. They are found in nearly every habitat studied, including habitats that no other are able to withstand. Bacteria all share these five characteristics -All bacteria are -celled -All bacteria are. Their DNA is not surrounded by a membrane. -Cell in bacteria are not surrounded by membranes. -The DNA of bacteria is made of a single. -All bacteria reproduce asexually by fission. Bacteria are the smallest organisms measuring from micrometres. It contains a that provides support and protection for the contents of the cell. Some are also covered by a capsule. The cytoplasm contains, responsible for the formation of proteins and DNA. The DNA forms a single chromosome and forms a rather than a strand. Some bacteria have a whip-like that act like propellers moving the organism forward. Bacteria are by their shape, reaction to being stained, nutrition and respiration. Bacterial Cell Shape Bacteria can be classified by shape. -A spherical cell is called a (pl. cocci) -A rod-shaped cell is called a (pl. bacilli) -A spiral-shaped cell is called a (pl. spirilla) 1

2 Staining bacteria results in two forms: gram- (purple) vs. gram (pink). Gram positive: accepts crystal violet stain. Nutrition Nutrition means obtaining and a source of to produce the organic compounds needed for cellular metabolism. Most bacteria are and obtain energy by breaking down organic molecules from their environment. Some are, absorbing nutrients from living organisms. Others are, decomposing dead organic matter. Some bacteria are autotrophs and produce their own compounds. (example- cyanobacteria (blue-green bacteria) are photoautotrophs using for energy, but they lack true chloroplasts. Gram negative: Peptidoglycan layer is covered. Mode of nutrition Photoautotroph Chemoautotroph Photoheterotroph Chemoheterotroph Energy Source Light Inorganic Chemicals Light Carbon Source Carbon Dioxide Carbon Dioxide Nutrition Most are although some are autotrophs. The autotrophic bacteria either use as a source of energy (chemoautotrophs) or are (photoautotrophs). Some are parasites which live off a living Some are, feeding off dead organisms and (i.e., decomposers). Leucothrix mucor 2

3 Respiration Chemical reactions take place on the of the cell membrane so that gases can pass into and out of cells easily. All living things must carry out cellular to receive energy. Bacteria differ in whether or not they require oxygen. If respiration requires oxygen, bacteria are termed. If oxygen is absolutely necessary for survival they are called aerobes. Bacteria that carry out respiration without oxygen are called. Presence of oxygen kills some bacteria and these are called obligate. (example- Clostridium botulinum produces toxins that can cause an extreme form of food poisoning called botulism.) Another group of bacteria can survive with or without oxygen and they are called anaerobes. Reproduction Bacteria reproduce asexually and divide by the process of. In binary fission, the parent cell divides into two offspring cells that are completely. There is no exchange of genetic material so the process is. E. coli produces between bacteria in 12 hrs Asexual - Binary Fission reproduce by simply splitting in two The DNA is copied and the divides into two identical cells. When conditions begin to, either through decrease of food or space, or cooler temperatures, some bacteria take part in a type of sexual reproduction called. In conjugation the two cells join briefly and one cell donates some (called plasmid) to the other one. Sexual reproduction genetic information from two different individuals and increases variation. Sexual - Conjugation Sexual reproduction combines from two different individuals and increases variation. do not technically reproduce sexually but can mix genes with one another. Transformation - Bacteria can also pick up pieces of DNA from the 3

4 Transduction - sometimes transfer pieces of DNA from one cell to another. is a large source of genetic diversity in bacteria. Under ultraviolet light in a Petri dish containing laundry whitener, symbiotic bacteria with a mutant blub gene (lower right) fluoresce brightly, while the same bacteria with no mutation only glow slightly (top right), and bacteria with another mutation (in the exoy gene) are completely dark. When growth conditions become extremely unfavorable, many bacteria form structures called endospores. Endospores are DNA and a small amount of enclosed in a tough cell wall. They are to extremes in temperature, drying, and harsh chemicals. Kingdom Monera Classification The Phyla Gram negative Gram positive No cell wall Exotic cell wall Archeabacteria Gracilicutes Firmicutes bacteria Non-photosynthetic bacteria non-oxygen producing bacteria oxygen producing bacteria (rod or cocci) bacteria (other shapes) Most pathogenic i.e. Lyme Disease Salmonella Others: E.coli in gut Live in sediments and lakes. Release sulpher Cyanobacteria (blue-green algae) C. Botulinum S. pneumoniae Dental/gum diseases 4

5 Tenericutes Mendosicutes bacteria (ancient) Other strains of pneumonia Anaerobic Methanogens- live in the gut of animals, swamps and marshes. Produce all the methane found in the Earth s atmosphere. Halophiles- - found in salt lakes such as the Dead Sea. Thermophiles hot, acidic environments such as hot springs. The pros and cons of Bacteria Bacteria atmospheric nitrogen into a useable form of nitrogen. (nitrogen-fixers) Bacteria play an important role in recycling by down dead and decaying organic matter. Used to eliminate or toxic and hazardous waste and spills. Also used in sewage treatment to decompose the 5 kg of solid waste produced daily. Bacteria is used to produce foods that help maintain a healthy balance of microorganisms in the digestive system. Only a small percentage of prokaryotes are, or disease causing. These bacteria produce deadly toxins in the human body that cause disease symptoms. are seldom fatal and cause fever, vomiting and diarrhea. E. coli, Salmonella. are highly toxic, do not cause a fever and are often fatal. Tetanus and botulism. Example- Toxins released by the bacterium Streptococcus pneumoniae may result in symptoms of pneumonia. Review Questions 1. Why are bacteria classified in their own kingdom and not with plants, animals, protists, or fungi? 2. What features are shared by prokaryotes? 3. What feature(s) might cause cyanobacteria to be classified as plants by some taxonomists? 4. Describe three shapes that bacteria can have. 5. Why is endospore formation important to bacteria? 6. What method of reproduction is used in bacteria? 7. What is conjugation in monerans? Why is it important? 8. How is conjugation different from transformation? 9. A protective slime coat around some species of bacterium known as a makes them more capable of causing disease. 10. Why are monerans considered more primitive than protists? 11. What is the difference between a saprobe and a parasite? 12. How do obligate aerobes differ from facultative aerobes? 13. are organisms that die in the presence of oxygen. 14. Monerans belong to a group of organisms known as prokaryotes. Discuss the differences between eukaryotes and prokaryotes in terms of cell wall, nuclear membrane, and chromosomes. 15. Why does dried or salted food resist spoiling by bacteria? 16. Give specific examples showing the importance of microbial sterility in a) your kitchen b) a microbiology lab 17. Describe the results if all bacteria died. 18. Endospores a) are produced by viruses b) are reproductive structures c) are very delicate and can easily be killed d) are resting structures 19. An obligate anaerobe would a) grow equally well with or without free oxygen b) grow well with free oxygen but better without it c) die without oxygen d) grow only in the absence of free oxygen 20. Why are archaebacteria considered the oldest organisms on Earth? 5