Presentation on theme: "Viruses, Bacteria, Protists, and Fungi Ch. 7. Section 2: Bacteria The Bacterial Cell A Dutch merchant named Anton van Leeuwenhoek found bacteria in the."— Presentation transcript:
Section 2: Bacteria The Bacterial Cell A Dutch merchant named Anton van Leeuwenhoek found bacteria in the late 1600s Cell Structure Bacteria are prokaryotes. The genetic material in their cells is not contained in a nucleus A bacterial cell lacks a nucleus and also lacks many other structures, such as mitochondria and Golgi bodies, that are found in the cells of eukaryotes Flagellum: a long, whip-like structure that helps a cell to move.
Section 2: Bacteria The Bacterial Cell Cell Sizes Bacteria very greatly in size The largest is as big as a period at the end of a sentence The smallest is about a micrometer which is on millionth of a meter Cell Shapes Three basic shapes: spherical, rod-like, or spiral The chemical makeup of the cell wall determines the shape of a bacterial cell
Section 2: Bacteria Obtaining Food and Energy Bacteria must have a source of food and a way of breaking down the food to release its energy. Obtaining Food Some bacteria are autotrophs (make their own food) Some capture the sun’s energy Some use the chemical substances in their environment Respiration Some bacteria need oxygen to break down their food Some bacteria don’t need oxygen, in-fact, those bacteria die if there is oxygen in their surroundings
Section 2: Bacteria Reproduction Asexual Reproduction Bacteria reproduce by a process called binary fission, in which one cell divides to form two identical cells Asexual reproduction: is a reproductive process that involves only one parent and produces offspring that are identical to the parent During binary fission, a cell first duplicates its genetic material and then divides into two separate cells
Section 2: Bacteria Reproduction Sexual Reproduction Sexual reproduction: two parents combine their genetic material to produce a new organism, which differs from both parents Conjugation: one bacterium transfers some genetic material to another bacterium through a threadlike bridge Conjugation results in bacteria with new combinations of genetic material, then divide by binary fission, the new combinations pass to the offspring
Section 2: Bacteria Reproduction Endospore Formation Endospore: is a small, rounded, thick-walled, resting cell that forms inside a bacterial cell It contains the cells genetic material and some its cytoplasm Endospores can resist freezing, heating, and drying, they can survive for many years
Section 2: Bacteria The Role of Bacteria in Nature: bacteria are involved in oxygen and food production, environmental recycling and cleanup, and in health maintenance and medicine production Oxygen Production As autotrophic bacteria use the sun’s energy to produce food, they also release oxygen into the air Scientists believe that autotrophic bacteria were responsible for first adding oxygen to Earth’s atmosphere
Section 2: Bacteria The Role of Bacteria in Nature Food Production Helpful bacteria include the making of cheese, sauerkraut, or pickles Harmful bacteria causes food to spoil when they break down the food’s chemicals Pasteurization: the food is heated to a temperature that is high enough to kill most harmful bacteria without changing the taste of the food
Section 2: Bacteria The Role of Bacteria in Nature Environmental Recycling Decomposers: organisms that break down large chemicals in dead organisms into small chemicals; called “natures recyclers” They return basic chemicals to the environment for other living things to reuse Nitrogen-fixing bacteria help bacteria convert nitrogen gas from the air into nitrogen products that plants need to grow
Section 2: Bacteria The Role of Bacteria in Nature Environmental Cleanup Some bacteria help to clean up Earth’s land and water Some prefer the oil, they convert the poisonous chemicals in oil into harmless substances Scientists put these bacteria to work cleaning up oil spills
Section 2: Bacteria The Role of Bacteria In Nature Health and Medicine Some bacteria help you digest food but other compete for space with disease causing organisms, preventing the harmful bacteria from attaching to your intestines and making you sick The first medicine-producing bacteria were made in the 1970s By manipulating the bacteria's genetic material, scientists engineered bacteria to produce human insulin
Section 2: Bacteria Closing Activity List ways that bacteria are involved in oxygen and food production, in environmental cleanup, and in health maintenance and medicine production.