LEARN Plant Cell - Frey Scientific · 2018-05-08 · mobile, and unicellular. The animal-like protist is the amoeba, which is a term used to describe a single-celled eukaryote that

C2INVESTIGATION

C2 LEARN™ Plant CellKey Question: What organelles and structures make up a generalized plant cell, and what are their functions?

Online ResourcesAvailable at www.curiosityplace.com

Student Vocabulary WordsNote: The names and functions of general plant cell organelles and structures can be found in Table 1 of the investigation. Those organelles are not listed again here.

TEACHER BACKGROUND amoeba – protist that uses pseudopods for feeding and locomotion

autotrophic – describes organisms that are able to produce their own food

Euglena – protist genus that has chloroplasts and can be both an autotroph and a heterotroph

galacturonic acid – oxidized form of D-galactose and the main component of pectin found in the cell wall’s middle lamellae

heterotrophic – describes organisms that must consume food for nutrition

middle lamella – part of the cell wall made mostly of pectin; helps adjacent cells bind to each other

primary cell wall – cell wall layer between the middle lamella and the cell membrane that makes the cell wall sturdy; made mostly of cellulose

In this investigation, students will interact with the LEARN™ app to explore a generalized plant cell model. A cookie factory analogy will guide students as they identify and consider the structure and function of organelles.

Learning Goals ✔ Identify 17 structural features of a generalized plant cell.

✔ Explain the function of 17 plant cell structural features within the context of a factory analogy.

✔Compare and contrast plant and animal cells.

GETTING STARTED

Time 150 minutes

Setup and Materials1. Make copies of investigation sheets for students.

2. Have students work in small groups, depending on how many devices are available.

3. Make sure each group has a device with the LEARN™ app downloaded and ready to use.

Materials for each group

y Device with LEARN™ app

y Highlighters

y Colored 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

Engaging in Argument from Evidence

LS1.A: Structure and Function Structure and Function

Scale, Porportion, and Quantity

LEARN™ Plant Cell 119

ControlMaintenanceFul�llmentPower

nucleus nucleolus

chloroplast

central vacuole

lysosome

cytoplasm

cytoskeleton ribosomes

vesicle

mitochondria

Golgi apparatus

cell wall

rough ER

smooth ER cell membrane

LEARN™ PLANT CELL

Although many of the organelles found in plant cells are similar to those in animal cells, there are some important differences that allow for the special needs and functions of these diverse organisms. Students will use the LEARN™ app to explore a generalized plant cell in this investigation, highlighting the similarities and differences between plant and animal cells.

Without a strong skeleton to hold them up, plant cells need to provide support for their stems, which are sometimes very tall. Thus, in addition to the cell membrane (which animal cells have as well), plant cells 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

primary cell wall is the layer between the middle lamella and the cell membrane, and it contains mostly cellulose and pectin, as well. This makes the primary cell wall both strong and flexible.

In order to communicate with the other plant cells, the cell wall has openings called plasmodesmata. These channels are membrane-lined, allowing for the trafficking of molecules and even proteins from one cell to another.

Cell wall layers

Plant cell

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C2The cell wall can withstand high internal pressure created by another plant-specific organelle called the central vacuole. The central vacuole fills with water, food, and waste, creating pressure that helps stabilize the cell wall and keeps the plant upright. Evidence of this comes in the form of a plant that wilts when water supplies are low. The empty central vacuole cannot produce the pressure necessary to keep the structure supported, causing the plant to wilt.

Another important plant organelle is the chloroplast, a membrane-bound organelle that is found in many parts of the plant but is most abundant in the leaves. This structure captures sunlight and, along with water and carbon dioxide, produces glucose and oxygen. If you’d like more information about photosynthesis, Chloroplast Blast—from CPO Science’s “Energy Quest” Link series—provides a detailed, fun, and interactive look at photosynthesis in the chloroplast using a cooperative board game.

In addition to having some additional organelles, plant cells are also missing an organelle found in the generalized animal cell. This organelle, called a centriole, plays a role in cell division in animal cells. During mitosis, centrioles organize the mitotic spindles, which are cytoskeletal structures that will help pull the chromosomes apart. Instead of relying on these, plant cell mitotic spindles organize through a mechanism that is still not well understood but likely relies on the polar nature of the spindles.

A group of organisms that cannot be classified as plants or animals are the protists—a collection of diverse, often single-celled eukaryotic organisms. Although they are

typically both single-celled and microscopic, protists— as eukaryotes—still contain a nucleus and membrane-bound organelles.

First proposed in 1886 by Ernst Haeckel, the Kingdom Protista has changed over time based on new genetic, morphological, and biochemical information. Previously, a protist was any eukaryote that was not an animal, land plant, or fungus. Many protists have been reclassified into other groups based on new data.

Two protists will be featured in the games for Investigations 3 and 4—one of which is considered to be animal-like, and one plantlike. Animal-like protists are heterotrophic (they must consume food for nutrition), mobile, and unicellular. The animal-like protist is the amoeba, which is a term used to describe a single-celled eukaryote that can alter its shape via pseudopods—armlike extensions of the plasma membrane.

Plantlike protists are autotrophic (able to produce their own food); some are mobile, and some are multicellular. The plantlike protist Euglena contains chloroplasts, so it can carry out photosynthesis. Interestingly, Euglena can also consume its food, like a heterotroph. When feeding, a tail-like projection called a flagellum propels it toward food.

There are also fungus-like protists, which include organisms that have cell walls like plants but reproduce via spores like fungi. They also have the ability to move—at least at some point in their life cycle. The two most common types of fungus-like protists are slime molds and water molds.

Amoeba Euglena


5E LESSON PLAN

EngageAn earthworm has the ability to crawl and move around, but a sunflower remains rooted in one spot. Use the following discussion questions to help students focus on the structures and organelles they will observe with the LEARN™ app that are unique to plant cells: the cell wall, chloroplasts, and the central vacuole.

y Ask students which organism would benefit the most from having its cells surrounded by a thick, strong, rigid wall. Why?

y Which organism would benefit the most from having the ability to make its own food? Why?

y Which organism would benefit the most from having cells with a large water storage organelle?

ExploreHave students use the LEARN™ app to complete Investi-gation C2, LEARN™ Plant Cell. Students interact with the LEARN™ app to explore a generalized plant cell model. A cookie factory analogy will guide students as they identify and consider the structure and function of organelles.

ExplainPlasmodesmata, often illustrated as holes in a plant cell wall, are membrane-lined channels that form connections between plant cells. It may seem surprising, but scientists really don’t know much about how plasmodesmata work. It is known that proteins can travel

through plasmodesmata, as can harmful plant viruses. The nature of the cell-to-cell communication allowed by plasmodesmata is an active area of research.

Some animal cells also have channels between neighboring cells, called gap junctions. Although the functions of plasmodesmata and gap junctions are similar, the structures are very different. Instead of membrane-lined channels, gap junctions are protein-lined pores. Cardiac muscle cells use gap junctions for the transmission of electrical signals that control rhythmic contractions of the heart muscle.

ElaboratePlant Biomechanics

Your students have probably heard of biomechanics—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 back to Hooke’s first observations of cork cell structure in the 1600s? Plant biomechanics shows how plant cells, tissues, and structures can be modeled and studied as complex composite materials. An example of a plant biomechanics application is using different types of wood for musical instruments, depending on the acoustic quality you want to achieve. The ability of plants to perceive and respond to gravity, touch, and wind is also a fascinating and active area of plant biomechanics research.

The International Plant Biomechanics Conference is held every three years. The conference is held every three years. Have students visit their website. What scientific topics are listed for the conference? Ask students to select one of the 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.

LEARN™ PLANT CELL

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C2 LEARN™ Plant Cell Cell Quest 241

Copyright © CPO ScienceCan be duplicated for classroom use

A2Explore INVESTIGATION


C2 LEARN™ Plant CellWhat organelles and structures make up a generalized plant cell, and what are their functions?

What organelles and structures make up a generalized plant cell, and how do they act like parts of a factory? How does a plant cell compare to an animal cell? Let us explore the inside of a plant cell using augmented reality with the LEARN™ app.

Inside a Plant Cell

1. Use the LEARN™ app viewer to explore the plant cell target below.

Materials: ✔ Device with LEARN™ app

✔ Highlighter

✔ Colored pencils, markers, and sticky notes or flags for customizing App Map

C2Explore INVESTIGATION

Name ____________________________________________ Date ________________________

Control Maintenance Fulfillment Power

a. Each color corresponds to one of the factory department categories described in Table 1. Identify the color for each category:

green purple orange yellow

b. Using colored pencils, shade the rows of the table with the colors that represent the categories.

c. Go back to the LEARN™ appanduseittofigureoutwhichplantcellorganelleorstructurebelongstoeachfunction, 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.

Inside a Plant Cell

Guiding the INVESTIGATION

Just as with the augmented animal cell, the LEARN™ plant cell model has four colored menu selections. Each color corresponds to one of the four factory department categories explained in Table 1. For example, when the green menu selector is chosen, the cell membrane, cell wall, plasmodesmata, nucleus, and nucleolus identification will be revealed. This allows students to see not only what these organelles and structures are called, but also how they can be

grouped according to related functions. By interacting with the augmented plant cell, selecting different menu color categories, and comparing what they observe with the arrangement of organelles in Table 1, students will be able to match the LEARN™ app menu selector colors with each represented department function category. After color-coding Table 1, students can work on filling in the missing organelle/structure names.

ADDRESSING MISCONCEPTIONS

Using a generalized plant cell model is a great way to begin exploring how cells work. Interestingly, this general plant cell does not actually exist! It is created to show all of the different features and functions that are possible for a plant cell. Plant cells come in a variety of shapes and sizes, and they 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.


TEACHING TIP

LEARN™ PLANT CELL

Department Cookie factory part Plant cell organelle or structure Function of the organelle or structure

ControlThe parts of the factory and cell that oversee what comes in and out, and give orders for how products are made

Factory gates and doors; shipping and receiving Cell membrane Surrounds the cytoplasm; allows some materials

in and out

Extra wall around factory for security and support Cell wall

Rigid outer layer surrounding the cell membrane; maintains cell shape and allows communication with outside environment and between cells

Gates in factory wall Plasmodesmata Openings in plant cell wall that allow transport and communication from cell to cell

Factory manager’s office; place where cookie recipes are kept

Nucleus Command center of cell; contains genetic blueprint for making proteins

Machine and tooling shop Nucleolus Dense spot in nucleus where ribosomes are made

MaintenanceThe parts of the factory and cell that provide structure, support, and cleanup

Factory space Cytoplasm Everything between the nucleus and membrane

Building structure Cytoskeleton Cell’s structural support system

Custodial staff Lysosome Small organelle with chemicals that break down food particles and worn-out cell parts

Safety department PeroxisomeCarries out fatty acid metabolism in plant cells as seedling grows; produces phytohormones that help with wound response and cell division

Water storage tank Central vacuole Stores water and sap; provides support

FulfillmentThe parts of the factory and cell that fulfill orders by manufacturing, assembling, and shipping product

Mixing/baking Ribosome Makes proteins that will stay inside the cell

Assembly line for one kind of cookie Rough ER Ribosomes on surface; makes proteins that will

leave the cell

Assembly line for a different kind of cookie Smooth ER No ribosomes on surface; produces lipids

Packaging room Golgi apparatus Packages and tags proteins that will leave the cell

Transportation cart Vesicle Small compartments used to transport materials around the cell

PowerThe parts of the factory and cell that generate energy needed for all processes

Solar panels on factory roof that convert sunlight to chemical energy stored in batteries

ChloroplastCarries out photosynthesis to convert light energy and carbon dioxide to chemical energy (food) such as glucose

Power plant/energy supply Mitochondria Produces energy for the cell in the form of ATP

Here is what Table 1 will look like with correct answers and color shading.

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C2 LEARN™ Plant CellCell Quest 242


Table 1: Comparing a Cell to a Cookie Factory

Department Cookie factory part Plant cell organelle or structure

Function of the organelle or structure

ControlThe parts of the factory and cell that oversee what comes in and out, and give orders for how products are made

Factory gates and doors; shipping and receiving

Surrounds the cytoplasm; allows some materials in and out

Extra wall around factory for security and support

Rigid outer layer surounding the cell membrane; maintains cell shape and allows communication with outside environment and between cells

Gates in factory wall Openings in plant cell wall that allow transport and communication from cell to cell

Factory manager’s office; place where cookie recipes are kept

Command center of cell; contains genetic blueprint for making proteins

Machine and tooling shop

Dense spot in nucleus where ribosomes are made

MaintenanceThe parts of the factory and cell that provide structure, support, and cleanup

Factory space Everything between the nucleus and membrane

Building structure Cell’s structural support system

Custodial staffSmall organelle with chemicals that break down food particles and worn-out cell parts

Safety Department

Carries out fatty acid metabolism in plant cells as seedling grows; produces phytohormones that help with wound response and cell division

Water storage tank Stores water and sap; provides support

Cell membrane

Nucleus

Nucleolus

Cell wall

Plasmodesmata

Cytoplasm

Cytoskeleton

Lysosome

Central vacuole

Peroxisome




FulfillmentThe parts of the factory and cell that fulfill orders by manufacturing, assembling, and shipping product

Mixing/baking Makes proteins that will stay inside the cell

Assembly line for one kind of cookie

Ribosomes on surface; makes proteins that will leave the cell

Assembly line for a different kind of cookie

No ribosomes on surface; produces lipids

Packaging room Packages and tags proteins that will leave the cell

Transportation cart Small compartment used to transport materials around cell

PowerThe parts of the factory and cell that generate energy needed for all processes

Solar panels on factory roof that convert sunlight to chemical energy stored in batteries

Carries out photosynthesis to convert light energy and carbon dioxide to chemical energy (food) such as glucose

Transformer that converts energy stored in batteries to the electricity used by the factory

Extracts energy from glucose and makes ATP for use in all of the cell’s processes

Plant Cell App Map

Coloring, labeling, and making notes on a diagram that summarizes what you saw in the LEARN™ app is a great way to remember and keep track of cell organelles and structures. You can use the App Map for reference in future investigations.

1. Label the App Map with the names of the cell parts.

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.

Department Cookie factory part Plant cell organelle or structure

Function of the organelle or structure

Table 1 continued

Rough ER

Ribosome

Smooth ER

Golgi apparatus

Chloroplast

Mitochondria

Vesicle

Plant Cell App MapStudents 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.

Guiding the INVESTIGATION


LEARN™ PLANT CELL




Stop and Think

1. What organelles does a typical plant cell have that an animal cell does not have?

The plant cell has a cell wall, plasmodesmata, chloroplasts, and alarge central vacuole. Animal cells do not have these organelles.

2. Why do plant cells need the organelles that are not found in animal cells?

Plants require the rigidity of a cell wall to keep them supported. Plasmodesmata are membrane-lined channels that allow cell-to-cell communication and transport. The water-filled central vacuoleprovides support from turgor pressure. Plants are immobile, and(with a few exceptions) are not consumers. Therefore, they need tomake their own food through photosynthesis, which is carried outin chloroplasts.




3. One of the plant cell function category departments in Table 1 has the same organelles as one of the 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 importance of this functional category of organelles.

The fulfillment department category has the same organelles for bothanimal and plant cells. These organelles work together to buildproteins, with instructions from the genetic code contained in the nucleus. Protein synthesis is crucial to all eukaryotic cells becauseof the many roles proteins have. The immune system depends onantibodies, which are proteins. Chemical reactions throughout allsystems of the body depend on proteins called enzymes. Hormonesand other chemical messengers are proteins. Actin and myosin, thestructural and movement components, are proteins. Hemoglobin isa protein that carries oxygen throughout the body to cells for use incellular respiration. These are just some of the important roles forproteins. It is estimated that anywhere from 10,000 to several billiondifferent proteins are necessary for human functions. Now that thegenome has been mapped out, some researchers are working onmapping out the proteome, which is an interesting, complex task.

Stop and Think You might want to have small groups use two devices at the same time—one to augment the LEARN™ animal cell using the target from the previous investigation, and one to augment this investigation’s plant cell model. Observers can look back and forth from one cell to the other to better compare and contrast. This will take considerable group cooperation and patience, but students will enjoy the challenge.

Guiding the INVESTIGATION SCIENCE AND LANGUAGE

Endoplasmic reticulum: endo-, from Greek meaning “inside;” reticulum, from Latin meaning “little net”

The endoplasmic reticulum is like a little network located inside the cytoplasm of the cell. Many organelles share common prefixes, suffixes, or roots. Here are a few to discuss with your students.

1. The suffix -some; from the Greek soma, meaning “body” Examples: lysosomes, ribosomes

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).

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Name ____________________________________________ Date ________________________

C2Evaluate INVESTIGATION

Now that you have had a chance to interact with an augmented plant cell and an augmented animal cell, let’s put your observations to work. Study the cell images and determine whether each is a plant cell or an animal cell,andgivejustificationforyourchoice.Next,answertheremainingfivequestionsabouttheimages.

1. PlantCell q Animal Cell q Justification:

Irregular shape; no cell wall; no central vacuoleor chloroplasts visible.

2. PlantCell q Animal Cell q Justification:.

Rectangular shape withthick cell wall; largecentral vacuole (Note:This is a pine-needletannin cell. The largecentral vacuole holds atannin deposit.)

X

X



Name ____________________________________________ Date ________________________

Evaluate INVESTIGATION C2


Rectangular shape; cell wall;central vacuole


Irregular shape; no cell wall;no chloroplasts or centralvacuole


Rectangular; can see nucleus but can’t see chloroplasts or central vacuole; cell wall is the defining feature of a plantcell (Note: These are onion-skin cells.)

X

X

X

WRAPPING UP

Have your students reflect on what they learned from the investigation by answering the following questions:

1. How is a plant cell like a cookie factory? What are the four main functional departments, and what is the importance of each?

2. What are the major differences between plant and animal cells?

TEACHING TIP

Identification of cell types in micrographs used on the Evaluate pages:

1. Transmission electron micrograph (TEM) of typical animal cell, showing nucleus.

2. Micrograph of the transverse section of tannin cell from an eastern white pine needle (Pinus strobus), showing a huge tannin deposit in the cell vacuole.

3. Light micrograph (40X) of onion epidermal cells, stained, with visible nuclei.


LEARN™ PLANT CELL



Name ____________________________________________ Date ________________________

C2Evaluate INVESTIGATION

6. Two different kinds of microscopes were used to produce the five micrographs. What are the types of microscopes, and which micrographs go with each type? (Hint: Choose from scanning electron microscope, transmission electron microscope, and conventional light microscope.)

Micrographs 1–4 are from a transmission electron microscope. Theyshow excellent detail, and they have a flat, 2D quality, which is theresult of the images being from ultrathin tissue sections. Image 5 isfrom a light microscope of the type typically found in a high schoolclassroom. The cells have been stained, and the medium-powermagnification 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 isdark and takes up enough space in the cell to be a vacuole (it is anucleus).

8. Which micrograph shows a cell capable of producing large amounts of protein? Explain.

Micrograph 4 shows a cell capable of producing large amounts ofprotein because there is an extensive network of rough endoplasmicreticulum, 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 characteristicsof a plant cell, except there are no chloroplasts, which is true of plantroot structures. They do not carry out photosynthesis, and do notneed chloroplasts. Micrograph 2 is a plant cell without easilyrecognized chloroplasts, but it was already identified as a pine-needlecell, due to the large tannin deposit.



Name ____________________________________________ Date ________________________

Evaluate INVESTIGATION C2

10. Which micrograph shows a plasma B cell, ready to produce and secrete antibodies? Give evidence to support your answer.

The plasma B cell is micrograph 4. This was already identified as asecretory protein producer, and antibodies are secreted proteins.

STEM CONNECTION

How Plants Can “See” and “Hear”

Plants don’t have eyes or ears but they can still respond to the presence of pathogens, and to environmental stress such as extreme temperatures, drought, or salinity. How do plants sense these environmental cues? Through cell membrane proteins, which receive messages and direct cells to respond accordingly. Scientists have uncovered a complex network of membrane protein interactions that occur between the parts of the proteins that extend outside of the cell, into the extracellular

matrix1. These interactions form an organized signal network that aids in plant growth and development, and acts as a sort of immune system. Knowing how plant stimulus/response systems work helps researchers that are trying to grow crops with greater resistance to environmental stresses such as pathogens and climate change. 1. University of Alabama at Birmingham. “Breakthrough study shows how plants sense the world: This understanding could help commercial crops resist pathogens and drought.” ScienceDaily, 19 January 2018.

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Documents

LEARN Plant Cell - Frey Scientific · 2018-05-08 · mobile, and unicellular. The animal-like protist is the amoeba, which is a term used to describe a single-celled eukaryote that