Prokaryotes - Archaea and Bacteria PDF

The Prokaryotes A prokaryotic cell does not have a true nucleus or Prokaryotes dominate the membrane-bound biosphere. Their collective organelles. biomass outweighs all eukaryotes combined by at least 10 fold. Until recently, all prokaryotes were pla...

The Prokaryotes A prokaryotic cell does not have a true nucleus or Prokaryotes dominate the membrane-bound biosphere. Their collective organelles. biomass outweighs all eukaryotes combined by at least 10 fold. Until recently, all prokaryotes were placed in a _____________ Monera kingdom. single kingdom called the _______ However, biologists now recognize that there are such great differences between two distinct groups of prokaryotes that they should be placed into separate ________. domains Classification of Prokaryotes They are separated into two different _______: domains Archaea Strep Domain: Domain: Archaea Bacteria Kingdom: Kingdom: Archaea Eubacteria  The Archaea 1. Under a microscope, archaea look very similar to the eubacteria. They are: equally small, lack nuclei, and have cell walls. 2. Chemically, the archaea are very different ___________. 3. The archaea lack the peptidoglycans found in the _____________ eubacteria. They also have different ______________. membrane lipids 4. Further, the DNA sequences of key archaeal genes are more like eukaryotes than those those of __________ of _________. eubacteria The archaea live in extremely harsh environments, such as: swamps, salt lakes and hot springs. archaic or ancient In fact, the word “archaea” means “__________________” since many of the known species of archaea live in extreme environments thought to resemble the harsh environments present millions of years ago.  Three Archaeal Groups Genetic analysis of the archaea reveals at least three different groups of archaea. Methanogens: getting energy a) These archaea have a unique way of _____________. They convert hydrogen gas and carbon dioxide into methane gas. b) _______ Oxygen is poisonous to these archaea. They must live in anaerobic environments such as ________ deep fresh water, marine mud, swamp mud and sewage. c) Methanogens also thrive in the _____________ digestive tracts of cows and termites. A cow can release 200 to 400 liters of methane gas per day.  Halophiles salt-loving archaea. These are the “________” These organisms live in environments that have very high salt concentrations, such as the Great Salt Lake and the Dead Sea.  Thermoacidophiles These archaea live in very ______ acidic environments that have very high ____________, temperatures such as the hot springs in Yellowstone National Park. These organisms can thrive in temperatures of ______ 110 °C and at a pH of less than ___. 2 They are often found around “_____________” black smokers which are hydrothermal vents that leak very hot, ____________ dark-colored, acidic water. Large communities of worms, clams, and crabs live near these vents and utilize the thermoacidophilic archaea as a primary food source. The Eubacteria These are the “true” bacteria. There is great variety in the organisms that belong to this kingdom. These bacteria are found in every environment on Earth. The eubacteria have a cell wall that contains a polysaccharide called peptidoglycan.  Some are _______ harmful and cause diseases, but most bacteria are ________________. benign or beneficial A relatively small number of species cause _______. disease cholera They are successful because of their rapid cell division (reproduction) and their great metabolic diversity. They can double their numbers every __________ 20 minutes and live in environments that support no other forms of life. Bacteria are found almost everywhere. The best environment for growth has: Suitable temperature: Moisture 80-100 °F. Suitable food Darkness source Space to grow Bacteria are very large in comparison to a virus. Prokaryotes are identified by several characteristics: 1. Shape. 2. The materials composing the cell wall. 3. The way they move. 4. The way they obtain energy. Bacteria exist in three basic shapes: 1. Cocci are spherical. 2. Bacilli are rod-shaped. 3. Spirilla are spiral shaped or curved.  Some bacteria are ______ motile and others do not move at all. Some move by means of _______, flagella which are whip-like structures used for movement. Some lash or snake forward. Others glide slowly over a layer of slime they secrete. Movement Most bacteria are __________________. harmless or beneficial Nodules of nitrogen fixing bacteria around the roots of plants. Some are _______________________. pathogenic (cause diseases) Staphylococcus Streptococcus  The structures seen in the prokaryotic cell: 1 – capsule 2 – cell wall 3 – plasma membrane 4 – cytoplasm 5 – flagella 6 – pili 7 – ribosomes 8 – chromosomal DNA (single, circular strand) 9 – plasmid DNA The cytoplasm does not contain any… …..membrane bound organelles. The chromosome consists of …. …..one single, circular, continuous molecule of DNA. The cytoplasm is filled with many _________. ribosomes A _______ capsule may be present cell wall outside of the _______. It is composed of a gluey polysaccharide _____________. It enables prokaryotes to adhere to their substrate or to other individuals in the colony. Some capsules protect against __________. dehydration Some capsules shield pathogenic bacteria from: Flagella: attacks by their host’s immune Long whip like structure system. used for movement. Pili are shorter and thinner than flagella. Pili serve to attach bacteria to: 1) a food source 2) the surface of a liquid 3) another bacteria during reproduction. Plasmid DNA: A small circular piece of DNA that is separate from the chromosome. A plasmid is generally one gene.  How Do Bacteria Obtain Energy? Most bacteria are ___________. heterotrophs They do not have the ability to _________________. make their own food The heterotrophic bacteria are further divided into…. ….saprophytes and parasites. Saprophytes: a. Saprophytes live on dead organic matter. b. Saprophytes are very important as decomposers. Parasites: a. A parasite is an organism that invades plants and animals and lives off of them. b. Host: The organism that the parasite is living off of. A few bacteria are __________. autotrophs They have the ability to __________________. make their own food Photoautotrophs: Photosynthetic organisms that use light energy from the sun to convert carbon dioxide and water into the organic molecule glucose, and oxygen. Chemoautotrophs: Use the energy from inorganic reactions as a source of energy to build molecules of glucose.  Growth and Reproduction If conditions are favorable for growth, bacteria can grow and divide at incredible rates. Many bacteria can divide every __________ 20 minutes (under ideal conditions). If reproduction continued unchecked at this rate, a single prokaryotic cell could give rise to a colony…. ….outweighing Earth in three days. In reality, prokaryotic reproduction is limited by: a) the eventual exhausting of food supply. b) being poisoned by their own metabolic waste. c) competition from other microbes. d) being consumed by other organisms.  Binary fission is a type of asexual reproduction where: one cell undergoes cell division to form two cells. When the Binary Fission bacterium has grown to nearly Two identical double its size: daughter cells it replicates its DNA and divides are formed. in half.  Endospore Formation When conditions for growth become __________, unfavorable many bacteria form structures called __________. endospores An endospore is formed ____________. inside of a cell The contents of the _________ cytoplasm draw up together and a ________ thick wall is formed around it. These endospores can…. ….survive extreme dryness, heat or cold. They can remain dormant _______ for months or years while waiting for _______________________ favorable growth conditions to return. The Importance of Bacteria Bacteria are vital to maintaining the living world. The prokaryotes can easily survive without the eukaryotes _________, but the eukaryotes are totally dependent on the __________. prokaryotes  All living things depend Bacteria are upon a constant supply Decomposers of: carbon, nitrogen, and These essential elements must other essential elements. be recycled when an organism dies. Bacteria are ___________ decomposers that help to ______ recycle these essential chemical elements. When an organism dies, it is attacked by bacteria and broken down into simpler materials.  Human Uses For Bacteria Bacteria are used to produce a wide variety of: foods and beverages. Some bacteria can Examples: sour cream, digest oil and are yogurt, cheese. helpful in cleaning up oil spills.  Bacterial Diseases in Humans Some bacteria are _________. pathogens A pathogen is a disease-causing agent. Bacteria produce diseases in one of two ways: Some bacteria: Other bacteria: damage the cells release toxins or and tissues by poisons in the body breaking down of the host. the cells for food.  Many of the diseases caused by bacteria can be prevented with the use of vaccines. A weakened or killed form of the Vaccine: pathogen that stimulates the body’s immune system to produce antibodies. Once the body has “learned” to make the correct antibody, the body will be able to respond rapidly if infected with the living, active form of the pathogen. This rapid response of the immune system is called ________. immunity Antibiotics Antibiotics are compounds that kill bacteria. They are effective against _______, bacteria but have no affect viruses on ______.