STAAR Biology: Assessment Activities. Cell Structure and Function. The Charles A. Dana Center at The University of Texas at Austin

Transcription

1 Cell Structure and Function Viruses: Structure, Replication, and Disease 69

2 70

3 Cell Structure and Function Teacher Pages Purpose The purpose of this station is to reinforce students understanding of the structure of viruses and how they replicate by infecting living cells. This activity also reinforces students understanding of how viruses can cause disease in plants and animals. Correlations to Texas Essential Knowledge and Skills Note: Text with a line through it indicates this part of the TEKS is not being addressed in this activity. Some TEKS statements printed here end with a semicolon or the word and with nothing thereafter this indicates that further TEKS statements follow but are not included here. (4) Science concepts. The student knows that cells are the basic structures of all living things with specialized parts that perform specific functions and that viruses are different from cells. The student is expected to: (C) compare the structures of viruses to cells, describe viral reproduction, and describe the role of viruses in causing diseases such as human immunodeficiency virus (HIV) and influenza. (Readiness standard) (2) Scientific processes. The student uses scientific methods and equipment during laboratory and field investigations. The student is expected to: (G) (H) analyze, evaluate, make inferences, and predict trends from data; and (Incorporated) communicate valid conclusions supported by the data through methods such as lab reports, labeled drawings, graphic organizers, journals, summaries, oral reports, and technology-based reports. (Incorporated) (3) Scientific processes. The student uses critical thinking, scientific reasoning, and problem solving to make informed decisions within and outside the classroom. The student is expected to: (C) (E) draw inferences based on data related to promotional materials for products and services; (Incorporated) evaluate models according to their limitations in representing biological objects or events; and (Incorporated) Teacher Pages 71

4 STAAR Biology: Assessment Activities Materials Model of HIV (1) Envelope (1) The following materials are included in the blackline masters for this station, which are available in color on the enclosed DVD. Station Information sheet (1 per station) Structures of Cells and Viruses sheet (1 per station) Lytic Infection Cycle sheet (1 per station) Lytic Infection Cards (1 set per station) Student Pages (1 copy per student) Supplementary Resources Animal Diversity Web: Kingdom Animalia. Retrieved May 13, 2011, from the University of Michigan Museum of Zoology website: accounts/information/animalia.html. General Information about Bacteriophages. Retrieved May 17, 2011 from the Phage Phorum website: Structure and Classification of Viruses. Retrieved May 17, 2011 from the website of the National Center for Biotechnology Information: NBK8174/. Protein that destroys HIV discovered. Retrieved May 16, 2011 from the Kurzweil Accelerating Intelligence Newsletter: Advance Preparation 1. Print one copy of all the blackline masters for this station from the enclosed DVD using a color printer. Color is essential to the station activities. Make one copy of the Student Pages (including the glossary) for each student. 2. Laminate the Lytic Infection Cycle sheet, the Structures of Cells and Viruses sheet, and the Lytic Infection Cards. Cut apart the cards and place them in a labeled envelope. 3. Assemble the HIV model or another suitable virus model. See the Blackline Masters for a picture of what the completed HIV model should look like. 72 Teacher Pages

5 Station Setup 1. Laminate a copy of the Station Information sheet and place it at the station table. Students will use this to confirm that the station is set up correctly. 2. Put the Lytic Infection Cycle sheet, the Structures of Cells and Viruses sheet, the envelope containing the Lytic Infection Cards, and the HIV model (or other suitable virus model) at the table. Procedures 1. Tell students to check the station setup against the Station Information sheet when they arrive at the table. If anything is missing or out of place, they should notify you. 2. Before students begin the station activity, take a few minutes to address common misconceptions they may have about viruses. Students often mistakenly think that viruses reproduce themselves independently and can therefore be considered to be living cells. A virus cannot replicate itself independently. Scientists have determined that a virus does not carry enough information to allow it to replicate (i.e., make copies of itself) without using the machinery and enzymes of a living cell. Whether a virus replicates by the lytic or lysogenic method, it must first attach to a living cell, inject its DNA or RNA into the cell, and then use the functions of that cell to make copies of itself. This process is referred to as replication not reproduction. A virus cannot replicate itself without making use of a living cell. TEKS Student Expectation 4(B) refers to viral reproduction. However, when explaining the processes of lytic or lysogenic infection to students, the terms replication or making copies are more accurate. Students may also believe that viruses are living organisms; they may have seen or heard advertisements that claim that medications or cleaning products can kill viruses. According to what scientists know and understand about viruses, viruses are nonliving organisms they do not exist as independent, living organisms. Therefore, how can one of these products kill something that is not alive? 3. Instruct students to work through the procedures and answer the questions with their teammate(s). 4. As students work through the station activity, circulate around the room, checking their work and responding to questions. Teacher Pages 73

6 STAAR Biology: Assessment Activities Guide to Student Responses Note: The suggested student responses presented below in italics represent the best possible answers to the student questions; actual student responses may vary. Essential Question Why is it necessary for a virus to invade a living cell to make copies of itself? Viruses do not have the capability to reproduce as living cells do. A virus must make use of a cell s functions, parts, and enzymes in order to replicate itself. Activities and Questions 1. Locate the Structures of Viruses and Cells sheet at this station. Carefully examine the structures of the plant cell, animal cell, bacteriophage virus, and influenza virus. Then fill in the Comparing Virus Structures to Cell Structures Venn diagram below. Comparing Virus Structures to Cell Structures Structures found in a virus Structures found in a living cell protein coat tail (bacteriophages) fibers capsid membrane envelope Structures found in a virus and a living cell nucleic acids vesicles nucleus vacuoles cell walls centrosomes cell membranes mitochondria Golgi complexes lysosomes nucleolus endoplasmic reticulum cytoplasm chloroplasts (plants) Answers may vary; students may include other structures found in plants and animal cells or viruses that are not labeled on the Comparing Virus Structures to Cell Structures sheet. 74 Teacher Pages

7 2. Scientists consider viruses to be nonliving. Based on the information you used to fill in the Venn diagram, would you support or refute this statement? Explain your position in the space below. According to the information in the Venn diagram, the only structure or component that a virus and a cell have in common is nucleic acid. The virus lacks all the other cellular structures, and without them, it cannot exist, thrive, and reproduce on its own. Thus, unlike living cells, viruses do not reproduce: They replicate by controlling the DNA and protein production of a living cell. 3. Some disinfectants, like the one pictured below, claim that they are effective at killing viruses. Does your knowledge of the structures and functions of a virus support or refute this claim? Explain your position in detail below. Viruses do not exhibit characteristics of a living organism and are therefore considered to be nonliving. The product s claim that it kills viruses is questionable, since only living things can be killed. A virus structure may be destroyed, rendering the virus incapable of entering a living cell to make copies of itself, but it is inaccurate to say a virus can be killed. Note: Advertisements like the one in the picture may lead students to develop misconceptions about science content. Stress to students that scientific claims about products are often inaccurate or misleading. Teacher Pages 75

8 STAAR Biology: Assessment Activities 4. Locate the Lytic Infection Cycle sheet and the envelope labeled Lytic Infection Cards. Place the cards in the proper sequence on the Lytic Infection Cycle sheet to represent how a virus can infect a living cell and cause the cell to replicate the virus. The correctly sequenced cards are shown below. Lytic Infection Cycle bacteriophage plasmid bacterial DNA viral DNA 76 Teacher Pages

9 5. Not all viruses replicate through lytic infection. Some viruses replicate by another method, called lysogenic infection. In this method, as in lytic infection, the virus injects DNA into the host cell. Then the virus DNA combines with the DNA of the host cell. This may not cause any damage to the cell for weeks, months, or years, but eventually the virus DNA begins a process of replication similar to the process of lytic infection. The human immunodeficiency virus (HIV) replicates by the lysogenic infection method, attacking the cells of our immune system. Why do you think a person infected with HIV has difficulty fighting infections? HIV replicates by lysogenic infection, meaning that the virus s DNA and the immune system cell s DNA combine. Once the virus has replicated, it breaks out of the host cell by a process called lysis. The newly replicated viruses repeat the process with other immune system cells, destroying them and eventually weakening the immune system to the point that it is unable to fight off infections. 6. Locate the model of HIV at this station. Carefully examine the model without removing any of its parts. If a scientist tried to use this model to understand the structure and function of HIV, what limitations would she have? Answers may vary. Possible responses listed below. The model may not represent all of the virus s structures. There is no means to test the model in a laboratory setting. It is not possible to see how the model behaves with a host cell. I need to remember... Viruses lack the cell structures necessary for reproduction. Viruses are considered to be nonliving. Viruses can replicate by two methods lytic infection and lysogenic infection. Lysogenic infections occur when the nuclear material of the virus combines with the DNA of a cell before replication of the virus begins. Viruses and cells have one structure in common, nucleic acids. HIV is a virus that infects and destroys immune system cells. Teacher Pages 77

10 STAAR Biology: Assessment Activities 78 Teacher Pages

11 Cell Structure and Function Blackline Masters Contents Station Information sheet Structures of Cells and Viruses sheet Lytic Infection Cycle sheet Lytic Infection Cards Student Pages Blackline Masters 79

12 STAAR Biology: Assessment Activities Station Information: Station Information: Viruses:Viruses: structure, replication, and causing diseases Structure, Replication, and Disease Structures of Viruses and Cells endoplasmic reticulum nucleus cell membrane nuclear membrane ribosomes mitochondrion vacuole endoplasmic reticulum cell wall nucleolus Golgi complex nucleus Golgi complex centrosomes mitochondria cytoplasm peroxisome vesicles plasma membrane plasma membrane chloroplasts lysosomes Animal Cell Plant Cell protein coat Collins-Dana Center nucleic acid DNA Bacteriophage virus tail Influenza virus RNA fibers membrane envelope Model of HIV Lytic Infection Cycle Virus attaches to a living host cell Virus injects its DNA into the host cell Host cell lyses (breaks apart) and released new viruses Host cell is fiiled with new viruses Virus DNA begins to interact (circularizes) with the host DNA New viruses are assembled from the protein of the host cell Lytic Infection Cards Virus DNA causes the host cell to synthesize proteins and DNA needed to repilcate new viruses 80 Blackline Masters

13 HIV Model transmembrane glycoprotein reverse transcriptase docking glycoprotein capsid lipid membrane viral RNA Collins-Dana Center HIV Model Blackline Masters 81

14 STAAR Biology: Assessment Activities Structures of Cells and Viruses nucleus endoplasmic reticulum cell membrane mitochondrion ribosomes vacuole cell wall endoplasmic reticulum nucleolus nucleus peroxisome Golgi complex vesicles mitochondria plasma membrane plasma membrane istockphoto chloroplasts lysosomes Animal Cell Plant Cell protein coat nucleic acid DNA Bacteriophage virus Influenza virus RNA tail istockphoto fibers istockphoto membrane envelope nuclear membrane Golgi complex centrosomes cytoplasm istockphoto 82 Blackline Masters

15 Lytic Infection Cycle 1 7 Virus attaches to a living host cell. Host cell lyses (breaks apart) and releases new viruses. 2 6 Virus injects its DNA into the host cell. Host cell is fiiled with new viruses. 3 5 Virus DNA begins to interact (circularizes) with the host DNA. New viruses are assembled from the protein of the host cell. 4 Virus DNA causes the host cell to synthesize the proteins and DNA needed to replicate more viruses. Blackline Masters 83

16 STAAR Biology: Assessment Activities Lytic Infection Cards bacteriophage plasmid bacterial DNA viral DNA 84 Blackline Masters

17 Cell Structure and Function Student Pages Purpose The purpose of this station is to reinforce your understanding of the structure of viruses and how they replicate by infecting living cells. This activity also reinforces understanding of how viruses can cause disease in plants and animals. Before You Begin Look over the Station Information sheet and make sure that all the items it lists are present at the station. If you notice a problem, notify the teacher immediately. Materials Station Information sheet Model of HIV Structures of Viruses and Cells sheet Lytic Infection Cycle sheet Lytic Infection Cards Activities and Questions Essential Question Why is it necessary for a virus to invade a living cell to make copies of itself? Discuss the essential question with your teammate(s) and record your answer. Student Pages 85

18 STAAR Biology: Assessment Activities 1. Locate the Structures of Viruses and Cells sheet at this station. Carefully examine the structures of the plant cell, animal cell, bacteriophage virus, and influenza virus. Then fill in the Comparing Virus Structures to Cell Structures Venn diagram below. Comparing Virus Structures to Cell Structures Structures found in a virus Structures found in a living cell Structures found in a virus and a living cell 2. Scientists consider viruses to be nonliving. Based on the information you used to fill in the Venn diagram, would you support or refute this statement? Explain your position in the space below. 86 Student Pages

19 3. Some disinfectants, like the one pictured below, claim that they are effective at killing viruses. Does your knowledge of the structures and functions of a virus support or refute this claim? Explain your position in detail below. Our Product Kills Flu Viruses! Collins-Dana Center 4. Locate the Lytic Infection Cycle sheet and the envelope containing the Lytic Infection Cards. Place the cards in the proper sequence on the Lytic Infection Cycle sheet to represent how a virus can infect a living cell and cause the cell to replicate the virus. Student Pages 87

20 STAAR Biology: Assessment Activities 5. Not all viruses replicate through lytic infection. Some viruses replicate by another method, called lysogenic infection. In this method, as in lytic infection, the virus injects DNA into the host cell. Then the virus DNA combines with the DNA of the host cell. This may not cause any damage to the cell for weeks, months, or years, but eventually the virus DNA begins a process of replication similar to the process of lytic infection. The human immunodeficiency virus (HIV) replicates by the lysogenic infection method, attacking the cells of our immune system. Why do you think a person infected with HIV has difficulty fighting infections? 6. Locate the model of HIV at this station. Carefully examine the model without removing any of its parts. If a scientist tried to use this model to understand the structure and function of HIV, what limitations would she have? 7. Now that you have completed these questions, return to the essential question at the beginning of the activity. Would you like to modify or change your answer? Write any modifications to your answer below. Note: Because other students are going to do the activity after you, be sure to put all the materials at the station back as you found them. Sometimes there will be materials that need to be renewed or replaced. If you need assistance or have any questions, ask your teacher. 88 Student Pages

21 I Need to Remember... Complete this part after class discussion of this station. I need to remember... Student Pages 89

22 STAAR Biology: Assessment Activities Glossary Bacteriophage A bacteriophage is a virus that attacks and destroys bacteria. Lysis Lysis is the destruction of a living cell. Lysogenic Infection Lysogenic infection is one method by which viruses replicate. In lysogenic infection, the virus s genetic material combines with the DNA of the cell it invades. Lytic Infection Lytic infection is another method by which viruses replicate. In this method, a virus injects its genetic material into a living cell, causing the cell to make copies of the virus. This method destroys the cell. Replication Replication is the process of making copies or duplicating; viruses increase in numbers through replication. 90 Student Pages