7Th Gr Science-From Bacteria To Plants Ch 2 Sec 2

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Bacteria

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Bacteria are single-celled organisms. They are prokaryotes. The genetic material in their cells is not contained in a nucleus. They have three shapes: spherical-shaped, rodlike, and spiral-shaped.

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cytoplasm

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The region of a cell located inside the cell membrane (in prokaryotes) or between the cell membrane and nucleus (in eukaryotes); contains a gel-like material and cell organelles.

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Ribosome

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A tiny structure located in the cytoplasm of a cell where proteins are made.

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Flagellum

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A long, whiplike structure that extends from the cell membrane and passes out through a cell wall. A flagellum helps a cell to move, much as kicking your feet helps you swim. A bacterial cell can have have many flagella, one, or none. Bacteria that do not have flagella cannot move on their own. Instead, they depend on air, water currents, clothing, and other objects to carry them from one place to another.

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Kingdoms of Bacteria

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There are two kingdoms of bacteria:
1) Archaebacteria-which means "ancient bacteria". These existed on Earth for billions of years before dinosaurs appeared. Many archaebacteria live in extreme environments; extreme heat, intestines of animals, in the mud at the bottom of swamps, in sewage. It is the bacteria that produce the foul odors that you may associate with these places.
2) Eubacteria-these bacteria do not live in extreme environments, but they live everywhere else, on you, in your body. Most are useful or harmless to you.

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Binary fission

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A process in which one cell divides to form two identical cells. Binary fission is a form of asexual reproduction (a reproductive process that involves only one parent and produces offspring that are identical to the parent. In this process, the cell duplicates its genetic material and then divides into two separate cells).

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Sexual Reproduction

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When two parents combine their genetic material to produce a new organism, which differs from both parents.

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Conjugation

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When one bacterium transfers some of its genetic material into another bacterial cell through a thin, threadlike bridge that joins the cells. After the transfer, the cells separate. Conjugation results in bacteria with new combinations of genetic material.

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What do all bacteria need to survive?

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All bacteria need:
1) a source of food
2) a way of breaking down the food to release the food's energy
3) survival techniques when conditions in their surroundings become unfavorable

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How do bacteria obtain food?

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1) Some bacteria are autotrophs and make their own food. Some make food by capturing and using the sun's energy as plants do. Some autotrophs, like those that live deep in the ocean, use the energy from chemical substances in their environment to make their food.
2) Some bacteria are heterotrophs and obtain their food by consuming autotrophs or other heterotrophs. They may consume a variety of foods-from milk and meat, to decaying leaves on the forest floor.

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Respiration

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The process of breaking down food to release its energy. Most bacteria need oxygen to break down their food. Some bacteria, however, do not need oxygen for respiration-for them, it is a poison.

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Endospore

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A small, rounded, thick-walled, resting cell that forms inside a bacterial cell. It contains the cell's genetic material and some of its cytoplasm. They can resist freezing, heating, and drying, so they can survive for many years. They are light-a breeze can lift and carry them to new places. If an endoscope lands in a place where conditions are suitable, it opens up. Then the bacterium can begin to grow and multiply.

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How are bacteria helpful to people?

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Bacteria are involved in fuel and food production, environmental recycling and cleanup, and the production of medicines.

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Archaebacteria

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These bacteria live in oxygen-free environments, such as the thick mud at the bottom of lakes and swamps. During respiration, they produce a gas called methane, which is the major component in about 20% of Earth's deposits of natural gas.

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How is helpful bacteria used with food?

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Some bacteria are helpful and are used to produce cheese, yogurt, buttermilk, sour cream, apple cider, olives, and sauerkraut. However, some bacteria are not helpful and break down food's chemicals, making the foods spoiled, which can make you very sick. Methods such as heating, refrigerating, drying, salting, or smoking foods help to preserve food by preventing the bacteria that cause spoiling from growing in the food.

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Decomposer

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An organism that breaks down large chemicals from dead organisms into small chemicals and returns important materials to the soil and water.

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Bacteria and Environmental Cleanup

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Some bacteria help to clean up Earth's land and water. They convert the dangerous chemicals in oil into harmless substances. They are used in cleaning up oil spills in oceans and gasoline leaks in the soil under gas stations.

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Bacteria and Health & Medicine

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Health: Many bacteria living in your body keep you healthy. In your digestive system, your intestines contain many bacteria-this is healthy and natural. Some bacteria help you digest your food. Some make vitamins that your body needs. Others compete for space with disease-causing organisms and prevent harmful bacteria from attaching to your intestines and making you sick.

Medicine: Some bacteria are medicine-producing bacteria, such as those that are used to create insulin for diabetics.