Lesson 1 What are Bacteria? Lesson 2 Bacteria in Nature Chapter Introduction Lesson 1 What are Bacteria? Lesson 2 Bacteria in Nature Lesson 3 What are Viruses? Chapter Wrap-Up Chapter Menu

What are bacteria and viruses and why are they important? Chapter Introduction

What do you think? Before you begin, decide if you agree or disagree with each of these statements. As you view this presentation, see if you change your mind about any of the statements. Chapter Introduction

Do you agree or disagree? 1. A bacterium does not have a nucleus. 2. Bacteria cannot move. 3. All bacteria cause diseases. Chapter Introduction

Do you agree or disagree? 4. Bacteria are important for making many types of food. 5. Viruses are the smallest living organisms. 6. Viruses can replicate only inside an organism. Chapter Introduction

What are Bacteria? What are bacteria? How do bacteria obtain food? Lesson 1 Reading Guide

Lesson 1 Reading Guide - Vocab What are Bacteria? bacterium flagellum fission conjugation endospore Lesson 1 Reading Guide - Vocab

Characteristics of Bacteria Bacteria are microscopic prokaryotes that live in almost every habitat on Earth and in or on almost every organism, both living and dead. bacteria from Greek bakterion, means “small staff” Lesson 1

Characteristics of Bacteria (cont.) What are bacteria? Lesson 1

Characteristics of Bacteria (cont.) Other prokaryotes, called archaea, are similar to bacteria and share many characteristics with them, including the lack of membrane-bound organelles. Lesson 1

Characteristics of Bacteria (cont.) A typical bacterium consists of cytoplasm and DNA surrounded by a cell membrane and a cell wall. Most bacteria have DNA that is one coiled, circular chromosome. Many bacteria also have one or more small circular pieces of DNA called plasmids that are separate from their other DNA. Lesson 1

Characteristics of Bacteria (cont.) Some bacteria have specialized structures that help them survive. Lesson 1

Characteristics of Bacteria (cont.) Bacteria are much smaller than plant or animal cells. They have one of three basic shapes: round or sphere-shaped rod-shaped spiral-shaped. Lesson 1

Characteristics of Bacteria (cont.) Bacteria live in many different places and obtain food in various ways. Some bacteria make their own food by using light energy, like plants. Others take in their nutrients from living hosts. Other bacteria use energy from chemical reactions to make their food. Lesson 1

Characteristics of Bacteria (cont.) Some bacteria break down food to obtain energy. These bacteria often live on dead organic matter. Lesson 1

Characteristics of Bacteria (cont.) How do bacteria obtain food? Lesson 1

Characteristics of Bacteria (cont.) Bacteria that can live where there is no oxygen are called anaerobic. Bacteria that need oxygen are called aerobic. Lesson 1

Characteristics of Bacteria (cont.) Some bacteria are able to find their resources by moving around with special whiplike structures called flagella. Lesson 1

Characteristics of Bacteria (cont.) Some bacteria twist or spiral as they move, and others use their pili like grappling hooks or create threadlike structures that enable them to push away from a surface. Lesson 1

Characteristics of Bacteria (cont.) Bacteria reproduce asexually by fission—cell division that forms two genetically identical cells. Genetic variation can be increased by a process called conjugation, in which two bacteria of the same species attach to each other and combine their genetic material. Lesson 1

Conjugation creates genetic diversity by transferring DNA between two bacteria cells. Lesson 1

Endospores An endospore forms when a bacterium builds a thick internal wall around its chromosome and part of the cytoplasm. An endospore can protect a bacterium from intense heat, cold, or drought. Lesson 1

Endospore Formation Lesson 1

Archaea Prokaryotes called archaea are similar to bacteria, but the ribosomes of archaea more closely resemble the ribosomes of eukaryotes than those of bacteria. Archaea contain molecules in their plasma membranes that are not found in any other known organisms and often live in extreme environments. Lesson 1

Bacteria are unicellular prokaryotes. Many bacteria feed on dead organic matter. Lesson 1

Bacteria can increase genetic diversity by sharing DNA through conjugation. Lesson 1

What are the long whiplike structures bacteria use to move? A. DNA B. cytoplasm C. bacterium D. flagella Lesson 1

A. conjugation C. reproduction B. fission D. inflammation During which process do two bacteria of the same species attach to each other and combine their genetic material? A. conjugation C. reproduction B. fission D. inflammation Lesson 1

Like green plants, some bacteria make their own food by using what type of energy? A. bacterial B. light C. anaerobic D. aerobic Lesson 1

1. A bacterium does not have a nucleus. 2. Bacteria cannot move. Do you agree or disagree? 1. A bacterium does not have a nucleus. 2. Bacteria cannot move. Lesson 1

Bacteria in Nature How can bacteria affect the environment? How can bacteria affect health? Lesson 2 Reading Guide

Lesson 2 Reading Guide - Vocab Bacteria in Nature decomposition nitrogen fixation bioremediation pathogen antibiotic pasteurization Lesson 2 Reading Guide - Vocab

Beneficial Bacteria Most bacteria are beneficial and only a fraction cause diseases. Many organisms, including humans, depend on bacteria to survive. Some bacteria help with digestion and other body processes. Lesson 2

Lesson 2

Beneficial Bacteria (cont.) Bacteria aid in the processes of decomposition and nitrogen fixation. Decomposition is the breaking down of dead organisms and organic waste. Nitrogen fixation is the conversion of nitrogen into a form that plants can use. Organisms use nitrogen to make proteins. Lesson 2

The roots of some plants, including beans and peas, have nodules that contain nitrogen- fixing bacteria. Lesson 2

Beneficial Bacteria (cont.) The use of organisms, such as bacteria, to clean up environmental pollution is called bioremediation. These organisms often break down harmful substances into less harmful material that can be used as landfill or fertilizers. Bacteria are used to make foods such as yogurt, cheese, buttermilk, vinegar, and soy sauce. Lesson 2

Beneficial Bacteria (cont.) What are some ways that bacteria are beneficial to the environment? Lesson 2

Harmful Bacteria Of the 5,000 known species of bacteria, relatively few are considered pathogens—agents that cause disease. pathogen from Greek pathos, means “to suffer”; and gen, means “to produce” Lesson 2

Harmful Bacteria (cont.) Some pathogens normally live in your body, but cause illness only when your immune system is weakened. Other bacterial pathogens can enter your body through a cut, the air you breathe, or the food you eat. Once inside your body, they can reproduce and cause disease. Lesson 2

Harmful Bacteria (cont.) Bacteria can harm your body and cause disease in one of two ways. Some bacteria make you sick by damaging tissue. Other bacteria cause illness by releasing toxins. Lesson 2

Harmful Bacteria (cont.) Describe one way that bacteria can be harmful to health. Lesson 2

Harmful Bacteria (cont.) Antibiotics are chemicals that stop the growth and reproduction of bacteria. Many types of bacteria have become resistant to antibiotics over time. Lesson 2

Harmful Bacteria (cont.) resistance Science Use the capacity of an organism to defend itself against a disease Common Use the act of opposing something Lesson 2

Harmful Bacteria (cont.) Random mutations occur to a bacterium’s DNA that enable it to survive or “resist” a specific antibiotic. Over time, resistant bacteria will reproduce to become more common. Lesson 2

Lesson 2

Harmful Bacteria (cont.) Over time bacteria on food reproduce and begin breaking down the food, causing it to spoil. Pasteurization is a process of heating food to a temperature that kills most harmful bacteria. Lesson 2

Harmful Bacteria (cont.) How does pasteurization affect human health? Lesson 2

Bacteria can help some organisms, including humans and cows, digest food. Lesson 2

Bacteria can be used to break down harmful substances such as uranium. Some bacteria are pathogens and cause diseases in humans and other organisms. Lesson 2

Which term best describes bacteria’s relationship to organisms? A. dangerous B. beneficial C. fatal D. useless Lesson 2

What term describes the conversion of nitrogen into a form that plants can use? A. nitrogen fixation B. decomposition C. bioremediation D. digestion Lesson 2

What is the name for chemicals that stop the growth and reproduction of bacteria? A. pathogens B. bacteria C. antibiotics D. antibodies Lesson 2

3. All bacteria cause diseases. Do you agree or disagree? 3. All bacteria cause diseases. 4. Bacteria are important for making many types of food. Lesson 2

What are Viruses? What are viruses? How do viruses affect human health? Lesson 3 Reading Guide

Lesson 3 Reading Guide - Vocab What are Viruses? virus antibody vaccine Lesson 3 Reading Guide - Vocab

Characteristics of Viruses A virus is a strand of DNA or RNA surrounded by a layer of protein that can infect and replicate in a host cell. A virus does not have a cell wall, a nucleus, or any other organelles present in cells. Viruses can have different shapes, such as crystal, cylinder, sphere, and bacteriophage shapes. Lesson 3

Viruses can have different shapes. Lesson 3

Characteristics of Viruses (cont.) A virus is not a living thing because it does not have all the characteristics of a living organism. A virus can make copies of itself in a process called replication, but it must rely on a living organism to do so. Lesson 3

Characteristics of Viruses (cont.) Are viruses alive? Explain why or why not. Lesson 3

Characteristics of Viruses (cont.) Viruses must use organisms to carry on the processes that we usually associate with a living cell. Viruses have no organelles so they are not able to take in nutrients or use energy. Viruses must be inside a cell, called a host cell, to replicate. Lesson 3

Characteristics of Viruses (cont.) When a virus enters a cell, it can either be active or latent. Latent viruses go through an inactive stage and their genetic material becomes part of the host cell’s genetic material. Once it becomes active, a virus takes control of the host cell and replicates. Lesson 3

Active Virus Lesson 3

Characteristics of Viruses (cont.) A virus can only attach to a host cell with specific molecules on its cell wall or cell membrane. After a virus attaches to a host cell, its DNA or RNA enters the host cell. Once inside, the virus either starts to replicate or becomes latent. Lesson 3

Latent Virus Lesson 3

Characteristics of Viruses (cont.) After a virus becomes active and replicates in a host cell, it destroys the host cell. Copies of the virus are then released into the host organism, where they can infect other cells. As viruses replicate, their DNA or RNA frequently mutates, enabling them to adjust to changes in their host cell. Lesson 3

Viral Diseases Most viruses attack and destroy specific cells, which causes the symptoms of disease. Some viruses, like influenza, begin to replicate immediately and cause symptoms soon after infection. Lesson 3

Viral Diseases (cont.) Other viruses, like HIV (human immunodeficiency virus), might not cause symptoms right away because the infected cells might continue to function normally for a period of time after infection. People infected with latent viruses might not know for many years that they have been infected. Lesson 3

Lesson 3

Treating and Preventing Viral Diseases Since viruses are constantly changing, viral diseases can be difficult to treat. One of the best ways to prevent a viral infection is to limit contact with an infected human or animal. Lesson 3

Treating and Preventing Viral Diseases (cont.) An antibody is a protein that prevents an infection in your body. When a virus infects a person, their body begins to make antibodies. Antibodies bind to viruses and other pathogens and prevent them from attaching to a host cell. Lesson 3

Treating and Preventing Viral Diseases (cont.) immunity from Latin immunis, means “exempt, free” Lesson 3

Lesson 3

Treating and Preventing Viral Diseases (cont.) Antibodies target viruses and signal the body to destroy them, making it easier for the body to fight infection if the same pathogen enters the body again. Natural immunity develops when a mother passes antibodies on to her unborn baby. Lesson 3

Treating and Preventing Viral Diseases (cont.) A vaccine is a mixture containing material from one or more deactivated pathogens, such as viruses. When an organism is given a vaccine for a viral disease, the vaccine triggers the production of antibodies. After being vaccinated against a particular pathogen, the organism will not get as sick if exposed to the same pathogen again. Lesson 3

Research with Viruses Scientists are researching new ways to treat and prevent viral diseases in humans, animals, and plants. Viruses have been used by some scientists to treat genetic disorders and cancer using gene transfer. Lesson 3

Research with Viruses (cont.) How do viruses affect human health? Lesson 3

A virus is a strand of DNA or RNA surrounded by a layer of protein. Lesson 3

Viruses cause human diseases such as chicken pox and influenza. A person’s body produces proteins called antibodies that prevent an infection by viruses. Lesson 3

What do viruses use to carry on the processes that we usually associate with a living cell? A. DNA B. antibodies C. organisms D. pathogens Lesson 3

What enables a virus to adjust to changes in their host cells? A. molecules B. mutations C. diseases D. pathogens Lesson 3

A vaccine contains what kind of deactivated substance? A. pathogens B. antibodies C. diseases D. viruses Lesson 3

5. Viruses are the smallest living organisms. Do you agree or disagree? 5. Viruses are the smallest living organisms. 6. Viruses can replicate only inside an organism. Lesson 3

Interactive Concept Map Chapter Review Standardized Test Practice Key Concept Summary Interactive Concept Map Chapter Review Standardized Test Practice Chapter Review Menu

Bacteria are unicellular prokaryotes, and viruses are small pieces of DNA or RNA surrounded by protein. Both bacteria and viruses may infect the human body; they can cause harmful diseases or can be useful. The BIG Idea

Lesson 1: What are Bacteria? Bacteria and archeans are unicellular organisms without nuclei. They have structures for movement, obtaining food, and reproduction. Bacteria exchange genetic information in a process called conjugation. They reproduce asexually by fission. Key Concepts 1

Lesson 2: Bacteria in Nature Bacteria decompose materials, play a role in the nitrogen cycle, clean the environment, and are used in food. Some bacteria cause disease, while others are used to treat it. Key Concepts 2

Lesson 3: What are Viruses? A virus is made up of DNA or RNA surrounded by a protein coat. Viruses can cause disease, can be made into vaccines, and are used in research. Key Concepts 3

Which type of cells are bacteria? A. eukaryotes B. organelles C. prokaryotes D. ribosomes Chapter Review - MC

When two bacteria of the same species attach to each other during conjugation, what are they combining? A. cytoplasm B. flagella C. cells D. genetic material Chapter Review - MC

What are disease-causing bacteria called? A. antibiotics B. pathogens C. proteins D. ribosomes Chapter Review - MC

What do viruses lack that would enable them to carry on life functions? A. DNA B. host cells C. organelles D. proteins Chapter Review - MC

Which term describes a virus that might not cause symptoms right away? A. active B. disease C. latent D. deactivated Chapter Review - MC

What is the name of the microscopic prokaryotes that live in or on almost every organism? A. eukaryotes B. organelles C. archaea D. bacteria Chapter Review - MC

In addition to being sphere-shaped or rod-shaped, what other shape might bacteria take? A. spiral-shaped B. spongy C. diamond-shaped D. bean-shaped Chapter Review - MC

A. bacterial resistance B. bioremediation C. decomposition What is the name for the process of heating food to a temperature that kills most harmful bacteria? A. bacterial resistance B. bioremediation C. decomposition D. pasteurization Chapter Review - MC

What is the name of a strand of DNA or RNA surrounded by a layer of protein that can infect and replicate in a host cell? A. bacterium B. bacteriophage C. virus D. mutation Chapter Review - MC

Which of these is a protein that prevents an infection in your body? A. virus B. pathogen C. antibody D. disease Chapter Review - MC