Bacteria (pages 48 57)

Size: px

Start display at page:

Download "Bacteria (pages 48 57)"

Susanna Gray
5 years ago
Views:

1 Bacteria (pages 48 57) The Bacterial Cell (pages 48 50) Key Concept: Bacteria are prokaryotes. The genetic material in their cells is not contained in a nucleus. Bacteria are single-celled organisms that do not have a nucleus. The outside of a bacterial cell is usually protected by a stiff cell wall. Just inside the cell wall is the cell membrane. The cell membrane controls what can go in and out of the bacterial cell. The area inside the cell membrane is the cytoplasm. The cytoplasm (SY toh plaz um) is a gel-like material. The cell s genetic material is in the cytoplasm. The genetic material looks like a tangled string. Some bacteria have a flagellum attached to the outside of the membrane. A flagellum (fluh JEL um) is a long, whiplike structure that helps a cell to move. Bacteria without a flagellum are carried by the wind or water. Answer the following questions. Use your textbook and the 1. The picture shows different parts of a bacterial cell. a. Circle the letter of the cytoplasm. b. Underline the letter of a flagellum. A B C 22

2 2. Is the following sentence true or false? Bacteria are living things made up of many cells. Obtaining Food and Energy (pages 50 51) Key Concept: Bacteria must have a source of food and a way of breaking down the food to release its energy. Bacteria need energy to live. This energy comes from food. Some bacteria can make their own food. Autotrophic bacteria either use energy from the sun or chemicals in the environment to make food. Other bacteria cannot make their own food. Heterotrophic bacteria get food by eating other organisms or the food made by other organisms. Breaking down food to release its energy is called respiration. Answer the following question. Use your textbook and the 3. Read each word in the box. In each sentence below, fill in the correct word. autotrophic energy heterotrophic respiration a. Bacteria that use energy from the sun to make food are. b. The process of breaking down food to release its energy is called. c. To carry out their functions, bacteria need a constant supply of. 23

3 Reproduction (pages 52 53) Key Concept: When bacteria have plenty of food, the right temperature, and other suitable conditions, they thrive and reproduce frequently. Bacteria reproduce in the right conditions. The right conditions include plenty of food and water and the right temperature. Bacteria reproduce by binary fission. In binary fission, one cell divides to form two identical cells. Binary fission is a form of asexual reproduction. Asexual reproduction involves only one parent. The parent produces offspring that are identical to it. Sometimes bacteria undergo conjugation. In conjugation (kahn juh GAY shun), one bacterial cell transfers some genetic material into another bacterial cell. Conjugation is a form of sexual reproduction. Sexual reproduction involves two parents. The offspring of sexual reproduction are genetically different from either parent. Answer the following questions. Use your textbook and the 4. Circle the letter of when bacteria will reproduce. a. anytime b. only when water dries up c. when there is plenty of food and the temperature is right 24

4 5. Read each word in the box. Use the words to complete the concept map about reproduction in bacteria. Asexual Binary fission Conjugation Reproduction Reproduction in bacteria can be a. Sexual involves in a process called involves in a process called One parent Two parents b. c. The Role of Bacteria in Nature (pages 54 57) Key Concept: Bacteria are involved in oxygen and food production, environmental recycling and cleanup, and in health maintenance and medicine production. You might think that bacteria are only harmful because they cause disease. However, most bacteria are harmless. Some are even helpful to people. When bacteria make food with the sun s energy, they release oxygen into the air. These bacteria help keep the right amount of oxygen in the air. 25

5 Foods like vinegar, yogurt, and cheeses are made with bacteria. Other kinds of bacteria cause food to spoil. Eating spoiled food can make you sick. Some bacteria break down the chemicals in dead organisms. Plants use these chemicals to grow. Bacteria can help clean up oil spills. The bacteria make the poisonous chemicals in oil harmless. You have bacteria in your intestines. These bacteria help you to digest food. Answer the following question. Use your textbook and the ideas on page 25 and above. 6. Fill in the table below. Write helpful if the role played by bacteria is helpful to people. Write harmful if the role is harmful to people. The Roles of Bacteria Role Helpful or Harmful to People? Cause diseases a. Give off oxygen b. Used to make foods c. Spoil foods d. Break down dead organisms e. Clean up oil spills f. 26

Name Block Chapter 6, Section 3, Bacteria, pages Information taken from Prentice Hall Science Explorer, Life Science, 2004

Name Block Chapter 6, Section 3, Bacteria, pages Information taken from Prentice Hall Science Explorer, Life Science, 2004 SOL LS.4 The student will investigate and understand how organisms can be classified. Key concepts include a) The distinguishing characteristics of domains of organisms b) The distinguishing characteristics