Chpt 27 Bacteria and Archaea

Describe the interactions between humans and bacteria.

-A minority cause disease. -Many form symbiotic relationships. -Digestion -Vitamin production -Inhibit pathogens

Distinguish between exotoxins and endotoxins and give an example of each.

-Exotoxins are secreted by a prokaryote and symptoms may be present even in the absense of the prokaryote. Ex. neurotixins -Endotoxins a component of the outer membrane that is released only after the bacteria die. Ex. lipopolysaccharide.

Distinguish between the structure and staining properties of gram-positive and gram-negative bacteria.

-Gram-positive bacteria have simpler walls with a relatively large amount of peptidoglycan in the cell which traps the violet dye in the cytoplasm. -Gram-negative bacteria have less peptidoglycan and are structurally more complex, with an outer membrane that contains lipopolysaccharides. The violet dye is easily rinsed from the cytopalsm and the cell appears pink or red.

Distinguish among mutualism, commensalism, and parasitism.

-Mutualism is a close association in which both organisms benefit. -Commensalism one organism benefits the other is neither harmed nor benefited. -Parasitism one organism benefits and the other is harmed.

Distinguish among obligate aerobes, facultative anaerobes, and obligate anaerobes.

-Obligate aerobe, requires oxygen for cellular respiration and cannot live without it. -Facultative anaerobe, makes ATP by aerobic respiration if oxygen is present or fermentation if oxygen is not. Can live with/without oxygen. -Obligate anaerobe, carries out fermentation cannot use oxygen and may be poisoned by it.

Distinguish among photoautotrophs, chemoautotrophs, photoheterotrophs, and chemoheterotrophs.

-Photoautotrophs: light for energy, CO2 for carbon. -Chemoautotrophs: inorganic compounds for energy, CO2 for carbon. -Photoheterotrophs: light for energy, organic compounds for carbon -Chemoheterotrophs: organic compounds for energy, organic compounds for carbon.

Describe three processes that produce recombinant DNA in prokaryotes.

-Transformation the uptake of DNA from the environment. -Transduction the transfer of new DNA through pages (virus). -Conjugation the exchange of plasmid through a sex pilis.

List three factors that give rise to high levels of genetic diversity in prokaryotes.

-rapid reproduction -mutation -genetic recombination

State the function(s) of each of the following prokaryotic features. 1) Capsule 2) Fimbriae 3) Sex pilus 4) Nucleoid 5) Plasmid 6) Endospore

1) Capsule, a sticky layer of polysaccharides or proteins that protect against dehydration and allow cells to attach. 2) Fimbriae, hair like proteins that help cells stick to their substrate or to one another. 3) Sex pilus, appendages that pull two daughter together prior to DNA transfer from one cell to another. 4) Nucleoid, in bacteria a circular region within the cell that contains all the genetic material. 5) Plasmid, smaller rings of separately replicating DNA. 6) Endospore, a thick-coated, resistant cell produced by a bacterial cell exposed to harsh conditions to preserve genetic information.

Explain why some Archaea are known as extremophiles. Describe the distinguishing feature of extreme halophiles and extreme thermophiles.

An extermophile is an organism that lives in an environment where conditions are so extreme that few other organisms can survive there. -Extreme halophiles live in an extremely saline environment. -Extreme thermophieles thrives in hot environments (60-80 degrees Celsius or hotter).

Define bioremediation. Give two examples of bioremediation involving prokaryotes,

Bioremediation is the use of organisms to remove pollutants from the soil, air, or water. -Anaerobic bacteria and archaea decompose the organic matter in sewage. -Breaking down radioactive waste. -Cleaning up oil spills.

Describe the structure, composition, and functions of prokaryotic cell walls.

Nearly all have a cell wall with peptidoglycan (not Arhcaeans). -Functions: shaping, physical protection, Osmotic protection; but plasmolysis inhibits growth. Prevents cells from bursting in a hypertonic enviornment. Major differences Gram+ and Gram-. -Structure and Composition: Most bacterial cell walls contain peptidoglycan, a network of modified-sugar polymers cross-linked by polypeptides. This molecular fabric encloses the entire bacterium and anchors other molecules that extend from its surface. Archaean cell wall contain a variety of polysaccharides and proteins but lack peptidoglycan.

Describe how prokaryotes carry out photosynthesis and cellular respiration when they lack compartmentalized organelles such as chloroplast and mitochondria.

Some prokaryotic cells have specialized membranes, usually infoldings of the plasma membrane, that perform metabolic functions. The infoldings of the plasma membrane, reminiscent of the cristae of mitochondria, function in cellular respiration in some aerobic prokaryotes. Photosynthetic prokaryotes called cyanobacteria have thykaloid membranes, much like those in chloroplasts.

Explain how R-plasmids confer antibiotic resistance on bacteria.

When a bacterial population is exposed to an antibiotic, individuals with the R-plasmid survive and increase in the overall population. Because R-plasmids also have genes encoded for sex pili, they can be transferred from one cell to another by conjugation