C2 LEARN™ Plant Cell

INVESTIGATION C2

C2 LEARN™ Plant Cell Key Question: What organelles and structures make up a generalized plant cell, and what are their functions? In this investigation, students will interact with the Online Resources ™ LEARN app to explore a generalized plant cell model. Available at www.curiosityplace.com A cookie factory analogy will guide students as they identify and consider the structure and function of Student Vocabulary Words organelles. Note: The names and functions of general plant cell organelles and structures can be found in Table 1 of the Learning Goals investigation. Those organelles are not listed again here. ✔✔Identify 17 structural features of a generalized plant cell. TEACHER BACKGROUND ✔✔Explain the function of 17 plant cell structural features within the context of a factory analogy. amoeba – protist that uses pseudopods for feeding and locomotion ✔ ✔Compare and contrast plant and animal cells. autotrophic – describes organisms that are able to produce their own food GETTING STARTED Euglena – protist genus that has chloroplasts and can be both an autotroph and a heterotroph Time 150 minutes galacturonic acid – oxidized form of D-galactose and the main component of pectin found in the cell wall’s Setup and Materials middle lamellae 1. Make copies of investigation sheets for students. heterotrophic – describes organisms that must consume 2. Have students work in small groups, depending on food for nutrition how many devices are available. middle lamella – part of the cell wall made mostly of 3. Make sure each group has a device with the pectin; helps adjacent cells bind to each other LEARN™ app downloaded and ready to use. primary cell wall – cell wall layer between the middle lamella and the cell membrane that makes the cell wall Materials for each group sturdy; made mostly of cellulose yyDevice with LEARN™ app yyHighlighters yyColored pencils, markers, and sticky notes or flags for customizing App Map

NGSS Connection This investigation builds conceptual understanding and skills for the following performance expectation. HS-LS1-1. Construct an explanation based on evidence for how the structure of DNA determines the structure of proteins, which carry out the essential functions of life through systems of specialized cells.

Science and Engineering Practices Disciplinary Core Ideas Crosscutting Concepts

Developing and Using Models LS1.A: Structure and Function Structure and Function Engaging in Argument from Evidence Scale, Porportion, and Quantity

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Although many of the organelles found in plant cells are primary cell wall is the layer between the middle lamella similar to those in animal cells, there are some important and the cell membrane, and it contains mostly cellulose differences that allow for the special needs and functions and pectin, as well. This makes the primary cell wall both of these diverse organisms. Students will use the strong and flexible. LEARN™ app to explore a generalized plant cell in this investigation, highlighting the similarities and differences In order to communicate with the other plant cells, between plant and animal cells. the cell wall has openings called plasmodesmata. These channels are membrane-lined, allowing for the Without a strong skeleton to hold them up, plant trafficking of molecules and even proteins from one cell cells need to provide support for their stems, which to another. are sometimes very tall. Thus, in addition to the cell membrane (which animal cells have as well), plant cells Cell wall layers also have a sturdy cell wall. This structure is made primarily of cellulose, a type of polysaccharide containing at least 3,000 glucose molecules. Cellulose is the most abundant naturally occurring polymer on the planet. The cell wall also includes soluble proteins and pectin—another type of polysaccharide. Pectins are a group of polysaccharides that are rich in galacturonic acid and found in non-woody structures of land plants, especially in fruit.

There are three main layers to the cell wall: the middle lamella, the primary cell wall, and the cell (or plasma) membrane. The middle lamella, made up of pectin, helps the cell walls of adjacent cells bind to one another. The

Plant cell

Control nucleus nucleolus Maintenance cytoskeleton ribosomes Ful llment Power central vacuole

vesicle lysosome

Golgi apparatus

chloroplast rough ER mitochondria

cell wall cytoplasm

smooth ER cell membrane 120 C2

The cell wall can withstand high internal pressure created typically both single-celled and microscopic, protists— by another plant-specific organelle called the central as eukaryotes—still contain a nucleus and membrane- vacuole. The central vacuole fills with water, food, and bound organelles. waste, creating pressure that helps stabilize the cell wall and keeps the plant upright. Evidence of this comes in First proposed in 1886 by Ernst Haeckel, the Kingdom the form of a plant that wilts when water supplies are Protista has changed over time based on new genetic, low. The empty central vacuole cannot produce the morphological, and biochemical information. Previously, pressure necessary to keep the structure supported, a protist was any eukaryote that was not an animal, land causing the plant to wilt. plant, or fungus. Many protists have been reclassified into other groups based on new data. Another important plant organelle is the chloroplast, a membrane-bound organelle that is found in many parts of Two protists will be featured in the games for the plant but is most abundant in the leaves. This structure Investigations 3 and 4—one of which is considered to captures sunlight and, along with water and carbon be animal-like, and one plantlike. Animal-like protists are dioxide, produces glucose and oxygen. If you’d like more heterotrophic (they must consume food for nutrition), information about photosynthesis, Chloroplast Blast— mobile, and unicellular. The animal-like protist is the from CPO Science’s “Energy Quest” Link series—provides a amoeba, which is a term used to describe a single-celled detailed, fun, and interactive look at photosynthesis in the eukaryote that can alter its shape via pseudopods— chloroplast using a cooperative board game. armlike extensions of the plasma membrane.

In addition to having some additional organelles, Plantlike protists are autotrophic (able to produce their plant cells are also missing an organelle found in own food); some are mobile, and some are multicellular. the generalized animal cell. This organelle, called a The plantlike protist Euglena contains chloroplasts, so centriole, plays a role in cell division in animal cells. it can carry out photosynthesis. Interestingly, Euglena During mitosis, centrioles organize the mitotic spindles, can also consume its food, like a heterotroph. When which are cytoskeletal structures that will help pull the feeding, a tail-like projection called a flagellum propels chromosomes apart. Instead of relying on these, plant it toward food. cell mitotic spindles organize through a mechanism that There are also fungus-like protists, which include is still not well understood but likely relies on the polar organisms that have cell walls like plants but reproduce nature of the spindles. via spores like fungi. They also have the ability to move— A group of organisms that cannot be classified as plants at least at some point in their life cycle. The two most or animals are the protists—a collection of diverse, often common types of fungus-like protists are slime molds single-celled eukaryotic organisms. Although they are and water molds.

Amoeba Euglena

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5E LESSON PLAN through plasmodesmata, as can harmful plant viruses. The nature of the cell-to-cell communication allowed by Engage plasmodesmata is an active area of research. An earthworm has the ability to crawl and move around, Some animal cells also have channels between but a sunflower remains rooted in one spot. Use the neighboring cells, called gap junctions. Although the following discussion questions to help students focus on functions of plasmodesmata and gap junctions are the structures and organelles they will observe with the similar, the structures are very different. Instead of LEARN™ app that are unique to plant cells: the cell wall, membrane-lined channels, gap junctions are protein- chloroplasts, and the central vacuole. lined pores. Cardiac muscle cells use gap junctions for the transmission of electrical signals that control rhythmic y yAsk students which organism would benefit the most contractions of the heart muscle. from having its cells surrounded by a thick, strong, rigid wall. Why? Elaborate yyWhich organism would benefit the most from having the ability to make its own food? Why? Plant Biomechanics yyWhich organism would benefit the most from having Your students have probably heard of biomechanics— cells with a large water storage organelle? the study of how physics relates to the movement and structure of living things. But do they know that plant biomechanics is an important field of study that dates Explore back to Hooke’s first observations of cork cell structure Have students use the LEARN™ app to complete Investi- in the 1600s? Plant biomechanics shows how plant cells, gation C2, LEARN™ Plant Cell. Students interact with the tissues, and structures can be modeled and studied as LEARN™ app to explore a generalized plant cell model. complex composite materials. An example of a plant A cookie factory analogy will guide students as they biomechanics application is using different types of wood identify and consider the structure and function for musical instruments, depending on the acoustic quality of organelles. you want to achieve. The ability of plants to perceive and respond to gravity, touch, and wind is also a fascinating Explain and active area of plant biomechanics research. Plasmodesmata, often illustrated as holes in a plant The International Plant Biomechanics Conference is held cell wall, are membrane-lined channels that form every three years. The conference is held every three years. connections between plant cells. It may seem surprising, Have students visit their website. What scientific topics are but scientists really don’t know much about how listed for the conference? Ask students to select one of the plasmodesmata work. It is known that proteins can travel topics and do some online research to learn more about it. Have them give a brief summary of a phenomenon that could be the subject of a presentation under the selected topic. For example, in the cell wall mechanics topic, a researcher might present findings about how cell walls are rearranged or changed as a plant cell grows or divides.

Evaluate • During the investigation, use the checkpoint questions as opportunities for ongoing assessment. • After the investigation, have students complete the assessment on the Evaluate student sheets. Students will identify micrographs as being plant or animal cells, and will give justification for choices.

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Explore INVESTIGATION C2A2 ADDRESSING MISCONCEPTIONS

Name ______Date ______Using a generalized plant cell model is a great way Materials: C2 LEARN™ Plant Cell ✔ Device with LEARN™ app to begin exploring how cells work. Interestingly, What organelles and structures make up a generalized plant ✔ Highlighter cell, and what are their functions? ✔ Colored pencils, markers, this general plant cell does not actually exist! It is What organelles and structures make up a generalized plant cell, and how and sticky notes or flags for created to show all of the different features and do they act like parts of a factory? How does a plant cell compare to an customizing App Map animal cell? Let us explore the inside of a plant cell using augmented reality functions that are possible for a plant cell. Plant with the LEARN™ app. cells come in a variety of shapes and sizes, and they  Inside a Plant Cell 1. Use the LEARN™ app viewer to explore the plant cell target below. might not have all of the organelles and structures depicted in the general model. Some plant cells, like those that make up xylem and phloem, are no longer living, and organelles are absent. Subsequent investigations will allow students to work with a number of specific cell type models so they can begin to appreciate and understand how diverse these basic units of life really are.

a. Each color corresponds to one of the factory department categories described in Table 1. Identify the color for each category: Control green Maintenance purple Fulfillment orange Power yellow

b. Using colored pencils, shade the rows of the table with the colors that represent the categories. c. Go back to the LEARN™ app and use it to figure out which plant cell organelle or structure belongs to each function, and complete the missing information in Table 1. Use a highlighter to draw a border around the rows of the table with organelles that are unique to plant cells.

Guiding the INVESTIGATION

 Inside a Plant Cell Just as with the augmented animal cell, the LEARN™ grouped according to related functions. By interacting plant cell model has four colored menu selections. with the augmented plant cell, selecting different Each color corresponds to one of the four factory menu color categories, and comparing what they department categories explained in Table 1. For observe with the arrangement of organelles in example, when the green menu selector is chosen, Table 1, students will be able to match the LEARN™ the cell membrane, cell wall, plasmodesmata, nucleus, app menu selector colors with each represented and nucleolus identification will be revealed. This department function category. After color-coding allows students to see not only what these organelles Table 1, students can work on filling in the missing and structures are called, but also how they can be organelle/structure names.

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TEACHING TIP

Here is what Table 1 will look like with correct answers and color shading. Plant cell organelle Department Cookie factory part Function of the organelle or structure or structure Factory gates and doors; Surrounds the cytoplasm; allows some materials Cell membrane shipping and receiving in and out Rigid outer layer surrounding the cell Control Extra wall around factory membrane; maintains cell shape and allows Cell wall The parts of the for security and support communication with outside environment and factory and cell between cells that oversee what Openings in plant cell wall that allow transport comes in and out, Gates in factory wall Plasmodesmata and give orders and communication from cell to cell for how products Factory manager’s office; Command center of cell; contains genetic are made place where cookie Nucleus blueprint for making proteins recipes are kept Machine and tooling shop Nucleolus Dense spot in nucleus where ribosomes are made Everything between the nucleus and Factory space Cytoplasm membrane Maintenance Building structure Cytoskeleton Cell’s structural support system The parts of the Small organelle with chemicals that break down factory and cell Custodial staff Lysosome that provide food particles and worn-out cell parts structure, support, Carries out fatty acid metabolism in plant cells and cleanup Safety department Peroxisome as seedling grows; produces phytohormones that help with wound response and cell division Water storage tank Central vacuole Stores water and sap; provides support Mixing/baking Ribosome Makes proteins that will stay inside the cell Assembly line for one Ribosomes on surface; makes proteins that will Fulfillment Rough ER The parts of the kind of cookie leave the cell factory and cell Assembly line for a Smooth ER No ribosomes on surface; produces lipids that fulfill orders different kind of cookie by manufacturing, Packages and tags proteins that will leave the assembling, and Packaging room Golgi apparatus shipping product cell Small compartments used to transport Transportation cart Vesicle materials around the cell Solar panels on factory Power Carries out photosynthesis to convert light roof that convert sunlight The parts of the Chloroplast energy and carbon dioxide to chemical energy to chemical energy factory and cell (food) such as glucose stored in batteries that generate energy needed for Power plant/energy Mitochondria Produces energy for the cell in the form of ATP all processes supply

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Explore INVESTIGATION C2 Explore INVESTIGATION C2

Table 1: Comparing a Cell to a Cookie Factory Table 1 continued Plant cell organelle or Function of the organelle or Plant cell organelle or Function of the organelle or Department Cookie factory part Department Cookie factory part structure structure structure structure Control Factory gates and Fulfillment Mixing/baking Makes proteins that will stay Surrounds the cytoplasm; allows The parts of the factory doors; shipping and Cell The parts of the factory Ribosome inside the cell some materials in and out and cell that oversee receiving membrane and cell that fulfill orders Assembly line for one Rough ER Ribosomes on surface; makes what comes in and out, Extra wall around Rigid outer layer surounding by manufacturing, kind of cookie proteins that will leave the cell and give orders for how assembling, and shipping factory for security and the cell membrane; maintains Assembly line for a No ribosomes on surface; products are made Cell wall product Smooth ER support cell shape and allows different kind of cookie produces lipids communication with outside Golgi Packages and tags proteins that environment and between cells Packaging room apparatus will leave the cell Gates in factory wall Openings in plant cell wall Plasmodesmata that allow transport and Small compartment used to Transportation cart communication from cell to cell Vesicle transport materials around cell Factory manager’s Command center of cell; Power Solar panels on factory Carries out photosynthesis to office; place where Nucleus contains genetic blueprint for The parts of the factory roof that convert Chloroplast convert light energy and carbon cookie recipes are kept making proteins and cell that generate sunlight to chemical dioxide to chemical energy energy needed for all energy stored in Machine and tooling Nucleolus Dense spot in nucleus where (food) such as glucose shop ribosomes are made processes batteries Transformer that Maintenance Everything between the nucleus Extracts energy from glucose Factory space Cytoplasm converts energy stored in The parts of the factory and membrane Mitochondria and makes ATP for use in all of batteries to the electricity and cell that provide the cell’s processes structure, support, and Building structure Cytoskeleton Cell’s structural support system used by the factory

cleanup Lysosome Small organelle with chemicals Custodial staff that break down food particles and worn-out cell parts  Plant Cell App Map Carries out fatty acid metabolism Coloring, labeling, and making notes on a diagram that summarizes what you saw in the LEARN™ app is a in plant cells as seedling grows; great way to remember and keep track of cell organelles and structures. You can use the App Map for reference Safety Department Peroxisome produces phytohormones that in future investigations. help with wound response and cell division 1. Label the App Map with the names of the cell parts. Stores water and sap; provides Water storage tank Central vacuole support 2. Use colored pencils or markers to color the organelles and structures to match the colors of the organelles that you observe in the LEARN™ app plant cell target. The colors are used to help differentiate between parts. In reality, these structures only appear as grayscale shadows and contours through powerful electron microscopes.

3. Use highlighters to draw attention to organelles that are unique to a plant cell.

4. Add notes as necessary to each structure label to summarize its function.

Guiding the INVESTIGATION

 Plant Cell App Map Students will need to use a completed Table 1 and the LEARN™ plant cell model to fill in and color the general plant cell App Map. Pairing up students is a good idea, but each student should customize their own App Map, which will serve as a reference for subsequent investigations. Encourage students to add notes and reminders as to the function of each organelle and structure.

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Explore INVESTIGATION C2 Explore INVESTIGATION C2

Stop and Think  3. One of the plant cell function category departments in Table 1 has the same organelles as one of the 1. What organelles does a typical plant cell have that an animal cell does not have? animal cell function category departments in Table 1 of the previous investigation. Which category is it, and why do you suppose these structures and functions are the same for animal and plant cells? Describe The plant cell has a cell wall, plasmodesmata, chloroplasts, and a the importance of this functional category of organelles. large central vacuole. Animal cells do not have these organelles. The fulfillment department category has the same organelles for both 2. Why do plant cells need the organelles that are not found in animal cells? animal and plant cells. These organelles work together to build Plants require the rigidity of a cell wall to keep them supported. proteins, with instructions from the genetic code contained in the Plasmodesmata are membrane-lined channels that allow cell-to-cell nucleus. Protein synthesis is crucial to all eukaryotic cells because communication and transport. The water-filled central vacuole of the many roles proteins have. The immune system depends on provides support from turgor pressure. Plants are immobile, and antibodies, which are proteins. Chemical reactions throughout all (with a few exceptions) are not consumers. Therefore, they need to systems of the body depend on proteins called enzymes. Hormones make their own food through photosynthesis, which is carried out and other chemical messengers are proteins. Actin and myosin, the in chloroplasts. structural and movement components, are proteins. Hemoglobin is a protein that carries oxygen throughout the body to cells for use in cellular respiration. These are just some of the important roles for proteins. It is estimated that anywhere from 10,000 to several billion different proteins are necessary for human functions. Now that the genome has been mapped out, some researchers are working on mapping out the proteome, which is an interesting, complex task.

Guiding the INVESTIGATION SCIENCE AND LANGUAGE

 Stop and Think Endoplasmic reticulum: endo-, from Greek meaning You might want to have small groups use two devices “inside;” reticulum, from Latin meaning “little net” at the same time—one to augment the LEARN™ animal cell using the target from the previous The endoplasmic reticulum is like a little network investigation, and one to augment this investigation’s located inside the cytoplasm of the cell. Many plant cell model. Observers can look back and organelles share common prefixes, suffixes, or roots. forth from one cell to the other to better compare Here are a few to discuss with your students. and contrast. This will take considerable group 1. The suffix -some; from the Greek soma, meaning cooperation and patience, but students will enjoy “body” Examples: lysosomes, ribosomes the challenge. 2. The prefix chloro-; from the Greek khloros, meaning “green” Examples: chloroplast, chlorophyll 3. The prefix cyto-; from the Greek kutos or kytos, meaning “hollow vessel” Example: cytoplasm Ask students if they can guess what a cytologist does (a cytologist studies the structure and function of cells). 126 C2

Evaluate INVESTIGATION C2 Evaluate INVESTIGATION C2

Name ______Date ______Name ______Date ______

Now that you have had a chance to interact with an augmented plant cell and an augmented animal cell, let’s 3. Plant Cell qX Animal Cell q put your observations to work. Study the cell images and determine whether each is a plant cell or an animal cell, and give justification for your choice. Next, answer the remaining five questions about the images. Justification:. Rectangular shape; cell wall;

1. Plant Cell q Animal Cell qX central vacuole Justification: Irregular shape; no cell wall; no central vacuole or chloroplasts visible.

4. Plant Cell q Animal Cell qX Justification:. Irregular shape; no cell wall; no chloroplasts or central vacuole 2. Plant Cell qX Animal Cell q Justification:. Rectangular shape with thick cell wall; large

central vacuole (Note: 5. Plant Cell qX Animal Cell q . This is a pine-needle Justification: Rectangular; can see tannin cell. The large nucleus but can’t see central vacuole holds a chloroplasts or central tannin deposit.) vacuole; cell wall is the defining feature of a plant cell (Note: These are onion- skin cells.)

WRAPPING UP TEACHING TIP

Have your students reflect on what they learned Identification of cell types in micrographs used on from the investigation by answering the following the Evaluate pages: questions: 1. Transmission electron micrograph (TEM) of 1. How is a plant cell like a cookie factory? typical animal cell, showing nucleus. What are the four main functional departments, 2. Micrograph of the transverse section of tannin and what is the importance of each? cell from an eastern white pine needle (Pinus 2. What are the major differences between plant strobus), showing a huge tannin deposit in the and animal cells? cell vacuole. 3. Light micrograph (40X) of onion epidermal cells, stained, with visible nuclei.

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Evaluate INVESTIGATION C2 Evaluate INVESTIGATION C2

Name ______Date ______Name ______Date ______

6. Two different kinds of microscopes were used to produce the five micrographs. What are the types 10. Which micrograph shows a plasma B cell, ready to produce and secrete antibodies? Give evidence to of microscopes, and which micrographs go with each type? (Hint: Choose from scanning electron support your answer. microscope, transmission electron microscope, and conventional light microscope.) The plasma B cell is micrograph 4. This was already identified as a Micrographs 1–4 are from a transmission electron microscope. They secretory protein producer, and antibodies are secreted proteins. show excellent detail, and they have a flat, 2D quality, which is the result of the images being from ultrathin tissue sections. Image 5 is from a light microscope of the type typically found in a high school classroom. The cells have been stained, and the medium-power magnification only reveals cell walls and nuclei.

7. Tannins are yellowish-brown substances found in the roots, wood, bark, leaves, and fruits of many plants. Tannins are often stored in the cell’s central vacuole. Which imicrograph is of a pine-needle cell with a tannin-filled vacuole? Give evidence to support your answer. Micrograph 2 shows a pine-needle cell. The tannin-filled vacuole is dark and takes up enough space in the cell to be a vacuole (it is a nucleus).

8. Which micrograph shows a cell capable of producing large amounts of protein? Explain. Micrograph 4 shows a cell capable of producing large amounts of protein because there is an extensive network of rough endoplasmic reticulum, where secretory proteins are manufactured.

9. One of the micrographs is from a root tip. Which one is it? Give evidence to support your answer. Micrograph 3 shows a root tip. The cell has all of the characteristics of a plant cell, except there are no chloroplasts, which is true of plant root structures. They do not carry out photosynthesis, and do not need chloroplasts. Micrograph 2 is a plant cell without easily recognized chloroplasts, but it was already identified as a pine-needle cell, due to the large tannin deposit.

STEM CONNECTION

How Plants Can “See” and “Hear” matrix1. These interactions form an organized signal Plants don’t have eyes or ears but they can still network that aids in plant growth and development, respond to the presence of pathogens, and to and acts as a sort of immune system. Knowing environmental stress such as extreme temperatures, how plant stimulus/response systems work helps drought, or salinity. How do plants sense these researchers that are trying to grow crops with environmental cues? Through cell membrane greater resistance to environmental stresses such as proteins, which receive messages and direct cells to pathogens and climate change. respond accordingly. Scientists have uncovered a 1. University of Alabama at Birmingham. “Breakthrough complex network of membrane protein interactions study shows how plants sense the world: This understanding that occur between the parts of the proteins that could help commercial crops resist pathogens and drought.” extend outside of the cell, into the extracellular ScienceDaily, 19 January 2018.

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