Wednesday, August 7, 2019
US History Essay Example for Free
US History Essay 4. Describe how prokaryotes carry out photosynthesis and cellular respiration when they lack compartmentalized organelles such as chloroplasts and mitochondria. The area of cellular respiration in prokaryotes is the respiratory membrane. For aerobic prokaryote the infoldings of the plasma membrane are similar to the cristae of mitochondria, whose purpose in eukaryotic cells is cellular respiration. In photosynthetic prokaryotes, the area responsible for cellular respiration is the thylakoid membrane. It functions are similar in manner to chloroplasts in eukaryotic cells. 5. Explain why prokaryotes are unable to grow in very salty or sugary foods, such as cured meats or jam. Prokaryotes have the ability to live harsh environments. Prokaryotes however are unable to live in very salty or sugary foods like cured meats or jams because they lack the essential nutrients that water etc provide. In response to these harsh conditions endospores are formed. In essence, endospores are a touch wall surrounding a set of chromosomes. Eventually as water is removed from the cell its metabolism halts and the rest of the cell disintegrates. In this manner prokaryotes die out in harsh conditions like sugary or salty foods. 6. State the function(s) of each of the following prokaryotic features: a. Capsule i. A capsule is a sticky layer that surrounds the cell wall of some prokaryotes, protecting the cell surface and sometimes helping to glue the cell to surfaces. b. fimbriae ii. A short, hairlike appendage of a prokaryotic cell that helps it adhere to the substrate or to other cells; also known as an attachment pilus. c. sex pilus iii. In bacteria, a structure that links one cell to another at the start of conjugation; also know as a conjugation pilus d. Nucleoid iv. A dense region of DNA in a prokaryotic cell. e. Plasmid v. A small, circular, double stranded DNA molecule that carries accessory genes separate from those of a bacterial chromosome. Plasmids are also found in some eukaryotes, such as yeasts. f. Endospores vi. A thick-coated, resistant cell produced by a bacterial cell exposed to harsh conditions. 7. List three factors that give rise to high levels of genetic diversity in prokaryotes. Rapid Reproduction- Rapid reproduction is comparable to a prokaryote reproducing by binary fission repeatedly. After rounds of division most of the offspring cells are identical Mutation- Genetic Recombination- 8. Describe three processes that produce recombinant DNA in prokaryotes.