Make a Model of a Plant or Animal Cell

Introduction: (Initial Observation)

What are cells? Cells are structural units that make up plants and animals. There are also many single cell organisms such as bacteria and amebas. What all cells have in common is a membrane (small ‘sacks’) composed mostly of water. The ‘sacks’ are made from a phospholipid bilayer. The membrane is semi-permeable (allowing some things to pass in and out of the cell while blocking others).

Since cells are very small, we have to use microscopes in order to see their details. Another problem with cell observation is that many material forming a cell are clear. We often need to use colorants that can help us see cell membrane or other cell elements.

Cells may be studied for different purposes. The main purpose is usually to gain a good understanding of the cell’s biological structure as well as feeding, defense, growth and reproduction. Studying cells is a branch of life science known as cell biology.

Making a model of a cell is an educational activity that can help a student to learn about the cell structure and transfer such knowledge to others as well.

In this project you will make models of a plant cells or animal cells. Your display may be used to answer any of the following questions.

How are plant cells different from animal cells?
What are the main parts of a plant cell?

Question:

I have a question about cells…I am doing a project on the white cell named Basophile and I need some ideas on how to do a model for school.. please give me some ideas on how to build it!

Information Gathering:

Find out about cells, which are the smallest living organisms that may live by themselves or as a part of a larger organism. Read books, magazines or ask professionals who have knowledge in this area in order to learn about a variety of plant and animal cells and learn in what aspects they are different. Keep track of where you got your information.

Following are samples of information that you may find.

So what is in a cell? The cell is a fluid like membrane that surrounds the contents of the cell. Each component will be discussed in more detail later.

While studying about cells, we will frequently hear the terms Eukaryotic and Prokaryotic. Lets see what they mean (by looking at a dictionary or an encyclopedia).

Eukaryotic: A single-celled or multi-cellular organism whose cells contain a distinct membrane-bound nucleus.

Prokaryotic: An organism of the kingdom Monera (or Prokaryotae), comprising the bacteria and cyanobacteria, characterized by the absence of a distinct, membrane-bound nucleus or membrane-bound organelles, and by DNA that is not organized into chromosomes. Also called moneran.

Animal Cell Structure

Animal cells are typical of the eukaryotic cell, enclosed by a plasma membrane and containing a membrane-bound nucleus and organelles. Unlike the cells of the two other eukaryotic kingdoms, plants and fungi, animal cells don’t have a cell wall.

The lack of a rigid cell wall allows animals to develop a greater diversity of cell types, tissues, and organs. Specialized cells that formed nerves and muscles — tissues impossible for plants to evolve — gave these organisms mobility. The ability to move about by the use of specialized muscle tissues is the hallmark of the animal world. (Protozoans locomote, but by nonmuscular means, i.e. cilia, flagella, pseudopodia.)

The animal kingdom is unique amongst eukaryotic organisms because animal tissues are bound together by a triple helix of protein, called collagen. Plant and fungal cells are bound together in tissues or aggregations by other molecules, such as pectin. The fact that no other organisms utilize collagen in this manner is one of the indications that all animals arose from a common unicellular ancestor.

Animals are a large and incredibly diverse group of organisms. Making up about three-quarters of the species on Earth, they run the gamut from sponges and jellyfish to ants, whales, elephants, and — of course — human beings. Being mobile has given animals the flexibility to adopt many different modes of feeding, defense, and reproduction.

Animal cells include the following parts:

• Centrioles – Centrioles are self-replicating organelles made up of nine bundles of microtubules and are found only in animal cells. They appear to help in organizing cell division, but aren’t essential to the process.

• Cilia and Flagella – For single-celled eukaryotes, cilia and flagella are essential for the locomotion of individual organisms. In multicellular organisms, cilia function to move fluid or materials past an immobile cell as well as moving a cell or group of cells.
• Endoplasmic Reticulum – The endoplasmic reticulum is a network of sacs that manufactures, processes, and transports chemical compounds for use inside and outside of the cell. It is connected to the double-layered nuclear envelope, providing a connection between the nucleus and the cytoplasm.

• Golgi Apparatus – The Golgi apparatus is the distribution and shipping department for the cell’s chemical products. It modifies proteins and fats built in the endoplasmic reticulum and prepares them for export to the outside of the cell.

• Lysosomes – The main function of these microbodies is digestion. Lysosomes break down cellular waste products and debris from outside the cell into simple compounds, which are transferred to the cytoplasm as new cell-building materials. Lysosomes are formed in golgi. You can see small spherical lysosomes around the golgi in the above image.
• Microfilaments – Microfilaments are solid rods made of globular proteins called actin. These filaments are primarily structural in function and are an important component of the cytoskeleton.
• Microtubules – These straight, hollow cylinders, composed of tubulin protein, are found throughout the cytoplasm of all eukaryotic cells and perform a number of functions.
• Mitochondria – Mitochondria are oblong shaped organelles that are found in the cytoplasm of every eukaryotic cell. In the animal cell, they are the main power generators, converting oxygen and nutrients into energy.

• Nucleus – The nucleus is a highly specialized organelle that serves as the information and administrative center of the cell.
• Peroxisomes – Microbodies are a diverse group of organelles that are found in the cytoplasm, roughly spherical and bound by a single membrane. There are several types of microbodies but peroxisomes are the most common. Peroxisomes are organelles that contain oxidative enzymes. They may resemble a lysosome, however, they are not formed in the Golgi complex. Peroxisomes are distinguished by a crystalline structure inside a sac which also contains amorphous gray material. They are self replicating, like the mitochondria. Components accumulate at a given site and they can be assembled into a peroxisome.
• Plasma Membrane – All living cells have a plasma membrane that encloses their contents. In prokaryotes (like bacteria), the membrane is the inner layer of protection surrounded by a rigid cell wall. Eukaryotic animal cells have only the membrane to contain and protect their contents. These membranes also regulate the passage of molecules in and out of the cells.
• Ribosomes – All living cells contain ribosomes, tiny organelles composed of approximately 60 percent RNA and 40 percent protein. In eukaryotes, ribosomes are made of four strands of RNA. In prokaryotes, they consist of three strands of RNA.

Plant Cell Structure

Plants are unique amongst the eukaryotes, organisms whose cells have membrane-enclosed nuclei and organelles, because they can manufacture their own food. Chlorophyll, which gives plants their green color, enables them to use sunlight to convert water and carbon dioxide into sugars and carbohydrates; chemicals the cell uses for fuel.

Like the fungi, another kingdom of eukaryotes, plant cells have retained the protective cell wall structure of their prokaryotic ancestors. The basic plant cell has the basic construction of a typical eukaryote cell, but does not have centrioles, lysosomes, cilia, or flagella as does the animal cell. Plant cells do have specialized structures: a rigid cell wall, central vacuole, plasmodesmata, and chloroplasts.

Plant cells include the following parts:

• Cell Wall – Like their prokaryotic ancestors, plant cells have a rigid wall surrounding the plasma membrane. However, it is a far more complex structure, and serves a variety of functions, from protecting the cell to regulating the life cycle of the plant organism.
• Chloroplast – The most important characteristic of plants is their ability to photosynthesize, i.e. make their own food by converting light energy into chemical energy. This process is carried out in specialized organelles called chloroplasts.
• Endoplasmic Reticulum – The endoplasmic reticulum is a network of sacs that manufactures, processes, and transports chemical compounds for use inside and outside of the cell. It is attached to the double-layered nuclear envelope, providing a connection between the nucleus and the cytoplasm. In plants, it also connects between cells via the plasmodesmata.
• Golgi Apparatus – The Golgi apparatus is the distribution and shipping department for the cell’s chemical products. It modifies proteins and fats built in the endoplasmic reticulum and prepares them for export as outside of the cell.
• Microfilaments – Microfilaments are solid rods made of globular proteins called actin. These filaments are primarily structural in function and are an important component of the cytoskeleton.
• Microtubules – These straight, hollow cylinders, composed of tubulin protein, are found throughout the cytoplasm of all eukaryotic cells and perform a number of functions.
• Mitochondria – Mitochondria are oblong shaped organelles found in the cytoplasm of all eukaryotic cells. In plant cells, they break down carbohydrate and sugar molecules to provide energy, particularly when light isn’t available for the chloroplasts to produce energy.
• Nucleus – The nucleus is a highly specialized organelle that serves as the information and administrative center of the cell.
• Peroxisomes – Microbodies are a diverse group of organelles that are found in the cytoplasm, roughly spherical and bound by a single membrane. There are several types of microbodies but peroxisomes are the most common.
• Plasmodesmata – Plasmodesmata are small tubes that connect plant cells to each other, providing living bridges between cells.
• Plasma Membrane – All living cells have a plasma membrane that encloses their contents. In prokaryotes and plants, the membrane is the inner layer of protection surrounded by a rigid cell wall. These membranes also regulate the passage of molecules in and out of the cells.
• Ribosomes – All living cells contain ribosomes, tiny organelles composed of approximately 60 percent RNA and 40 percent protein. In eukaryotes, ribosomes are made of four strands of RNA. In prokaryotes, they consist of three strands of RNA.
• Vacuole – Each plant cell has a large, single vacuole that stores compounds, helps in plant growth, and plays an important structural role for the plant.

Some Single Cell Organisms:

Amebas:

Amebas are tiny, one celled organisms in the Protista kingdom that can usually only be seen under a microscope. Amebas vary in size from about 1/100 inch (0.25 millimeter) to 1/10 inch (2.5 millimeters) across. Amebas can live in water, moist soil or in the bodies of animals and human beings. The single cell that makes up an ameba is a shapeless mass of protoplasm, the living, jelly like material found in the cells of all living things.

A thin, selectively permeable plasma membrane surrounds the protoplasm to hold the ameba together and allow water, gases, food, wastes, and other substances to pass in and out of the cell. The protoplasm extends and recoils in a pseudo pod , allowing the ameba to move about its environment. Cells that move in this way are called ameboid cells.

Amebas eat tiny living organisms and particles of dead and decaying matter. They engulf their food by slowly wrapping pseudo pods around a food particle. In this way, the food gets inside the cell. The section of the cell that contains the food is called a food vacuole. It floats in the protoplasm until the food is digested. All undigested food is forced out of the cell through the plasma membrane. Amebas in fresh water must remain hypertonic to their environment in order to survive, thus they contain contractile vacuoles to export excess water that enters the cell. Amebas reproduce by fission when they reach a certain size, and each new daughter cell is able to grow, feed, and divide. Most amebas are harmless to people, but some may cause diseases such amebic dysentery caused by infection in the large intestine.

Bacteria

Bacteria are prokaryotes, lacking well-defined nuclei and membrane-bound organelles, and with chromosomes composed of a single closed DNA circle. They come in many shapes and sizes, from minute spheres, cylinders and spiral threads, to flagellated rods, and filamentous chains. They are found practically everywhere on Earth and live in some of the most unusual and seemingly inhospitable places.

LEUKOCYTES (white cells)

Leukocytes, or white cells, are responsible for the defense of the organism. In the blood, they are much less numerous than red cells. The density of the leukocytes in the blood is 5000-7000 /mm3.

There are different types of Leukocyte.

Each type of leukocyte is present in the blood in different proportions:

neutrophil 50 – 70 %
eosinophil 2 – 4 %
basophil 0,5 – 1 %
lymphocyte 20 – 40 %
monocyte 3 – 8 %

Neutrophils are very active in phagocyting bacteria and are present in large amounts in the pus of wounds. Unfortunately, these cells are not able to renew the lysosomes used in digesting microbes and dead after having phagocyted a few of them.

Eosinophils attack parasites and phagocyte antigen-antibody complexes.

Basophil secrete anti-coagulant and vasodilatory substances as histamines and serotonin. Even if they have a phagocytory capability, their main function is secreting substances which mediate the hypersensitivity reaction.

Basophil Model

Basophils are the rarest leukocytes: less than 1%. They are quite small: 9-10 µm in diameter. Cytoplasm is very rich in granules which take a dark purple color. The nucleus is bi- or tri-lobed, but it is hard to see because of the number of granules which hide it.

Construction of a Basophil cell model is similar to any other animal cell. The only noticeable difference is the shape of nucleus and presence of dark purple granules. All other parts are the same.

Lymphocytes are cells which, besides being present in the blood, populate the lymphoid tissues and organs too, as well as the lymph circulating in the lymphatic vessel. The lymphoid organs include thymus, bone marrow (in birds bursa), spleen, lymphoid nodules, palatine tonsils, Peyer’s patches and lymphoid tissue of respiratory and gastrointestinal tracts.

Note: In a basophilic white cell, dark purple granules are the result of stain from a basic dye. Live cells do not contain such purple granules. Can you identify the nucleus in the basophilic cell in the right?

Question/ Purpose:

What do you want to find out? Write a statement that describes what you want to do. Use your observations and questions to write the statement.

The purpose of this project is to construct a model of an animal or plant cell.

Identify Variables:

When you think you know what variables may be involved, think about ways to change one at a time. If you change more than one at a time, you will not know what variable is causing your observation. Sometimes variables are linked and work together to cause something. At first, try to choose variables that you think act independently of each other.

Variables and hypothesis are not required for display projects.

Hypothesis:

Based on your gathered information, make an educated guess about what types of things affect the system you are working with. Identifying variables is necessary before you can make a hypothesis.

Variables and hypothesis are not required for display projects.

Experiment Design:

Design an experiment to test each hypothesis. Make a step-by-step list of what you will do to answer each question. This list is called an experimental procedure. For an experiment to give answers you can trust, it must have a “control.” A control is an additional experimental trial or run. It is a separate experiment, done exactly like the others. The only difference is that no experimental variables are changed. A control is a neutral “reference point” for comparison that allows you to see what changing a variable does by comparing it to not changing anything. Dependable controls are sometimes very hard to develop. They can be the hardest part of a project. Without a control you cannot be sure that changing the variable causes your observations. A series of experiments that includes a control is called a “controlled experiment.”

Experiment 1: Make a model of an animal cell

Introduction:

Making a model of a cell’s cross section is science combined with arts and crafts. You may use different material in constructing your model. Everything that you need for your model may be found at home or purchased from a local craft store. Following is a sample procedure. You may change it as you need. Make sure you include Plasma Membrane, Ribosomes, Nucleus, Cilia and Flagella, Endoplasmic Reticulum, Peroxisomes,
Mitochondria, Microtubules, Microfilaments, Lysosomes, Golgi Apparatus, Centrioles.

Procedure:

1. Get a piece of rigid foam board and cut it into a round or oval shape the size of the cell model that you want to make. Small models are usually about 9 inches long; Larger models are about 18 inches long.
2. Paint the board in skin color or pink with any water based paint such as latex paints or acrylic paints. This color represents the cytoplasm.
3. Nucleus: Cut a Styrofoam ball in half and paint it in light purple. This represents half of a nucleus. Place it in the center of the cell and secure it there with some wood glue or hot-melt glue.
4. Endoplasmic Reticulum: Get a few long strip of crepe paper (about 1 inch wide) and fold them a few times in a zigzag manner and place them around the nucleus.
5. Ribosomes: Use a black marker to put dots on the strip of paper used as endoplasmic reticulum. These dots represent ribosomes. Most ribosomes are attached to the endoplasmic reticular, but there are also free ribosomes which float in the cytosol. (What is cytosol? Cytosol is the fluid component of cytoplasm, excluding organelles and the insoluble, usually suspended, cytoplasmic components.)
6. Plasma Membrane: Get a long strip of clear plastic (about 3 inches wide) and wrap it around the cell model. This will be the cell membrane.
7. Mitochondria: Cut small pieces of soft foam and paint them like Mitochondria. Place a few of those in the cytoplasm. You may use peanuts for Mitochondria.
8. Microtubules: Cut small pieces of thin straws and place them on the cytoplasm. These will be microtubules.
9. Cilia: Cut short strands of yarn (2 or 3 inches long each) and connect them to the outside membrane of the cell. You may use a nail to push one end of these strands into the foam. If you don’t have access to yarn, cut some toothpicks in half and insert their sharper end in plasma membrane. About 1/2 inch of each toothpick remain outside to resemble the cilia.
10. Centrioles: Cut small – same size pieces of thin straw and glue them side by side to resemble Centrioles. Place one or two Centrioles on the cell background (cytoplasm).
11. Golgi Apparatus: Use light brown or yellow crepe paper to make a model of Golgi apparatus as shown in different images. Place that somewhere on the cell.
12. Microfilaments: Use cotton thread to represent microfilaments. Cut about 20 strands of 8 inches long thread and glue them on the cell’s cross section, parallel and close to the cell membrane.
13. Peroxisomes: Get a few more small foam balls and place them on the cell cross section. Color them different from lysosomes so you can distinguish them as peroxisomes.
14. Label all cell parts in your model.

Experiment 2: Make a model of a plant cell

Introduction: A model of a plant cell cross section is very similar to a model of an animal cell. Main differences are:

1. In animal cells the nucleus is usually in the center of the cell, but in a plant cell because of the large vacuole, it is more to the side. It is colorless, clear, and more dense than cytoplasm.
2. Plant cells have a rigid cell wall over the cell membrane. Cell wall in your model can be made of a long strip of cardboard.
3. Plant cells have vacuole, chloroplast and plasmodesmata. Plant cells have no cilia or flagella.

Procedure:

1. Get a piece of rigid foam board and cut it into a rounded corner rectangle shape the size of the cell model that you want to make. Small models are usually about 9 inches long; Larger models are about 18 inches long.
2. Paint the board light green with any water based paint such as latex paints or acrylic paints. This color represents the cytoplasm.
3. Vacuole: Cut a large kidney shape sponge and place it in the center of the model. Vacuole is the largest piece in your model. It occupies about 1/5th to 1/4th of the cell model area.
4. Nucleus: Cut a Styrofoam ball in half and paint it in light purple. This represents half of a nucleus. Place it between the vacuole and membrane and secure it there with some wood glue or hot-melt glue. It must be touching the vacuole.
5. Chloroplast: Cut some peanut shape foam or sponge and paint them green to represent chloroplast. You may paint unshelled peanuts and use them as chloroplast. (Some schools do not allow using food items in display models)
6. Endoplasmic Reticulum: Get a few long strip of crepe paper (about 1 inch wide) and fold them a few times in a zigzag manner and place them around the nucleus.
7. Ribosomes: Use a black marker to put dots on the strip of paper used as endoplasmic reticulum. These dots represent ribosomes. Most ribosomes are attached to the endoplasmic reticular, but there are also free ribosomes which float in the cytosol. (What is cytosol? Cytosol is the fluid component of cytoplasm, excluding organelles and the insoluble, usually suspended, cytoplasmic components.)
8. Plasma Membrane: Get a long strip of clear plastic (about 3 inches wide) and wrap it around the cell model. (or mount it like a wall surrounding the entire cell) This will be the cell membrane.
9. Cell Wall: Get a long strip of cardboard about 3 inches wide. Paint it green or brown and wrap it around the cell model, right over the cell membrane. (or mount it like a second wall or outer wall). This will be the cell wall.
10. plasmodesmata: Connect about 5 small buttons to the outside of cell wall to represent plasmodesmata.
11. Mitochondria: Cut small pieces of soft foam and paint them like Mitochondria. Place a few of those in the cytoplasm. You may use peanuts for Mitochondria.
12. Microtubules: Cut small pieces of thin straws and place them on the cytoplasm. These will be microtubules.
13. Golgi Apparatus: Use light brown or yellow crepe paper to make a model of Golgi apparatus as shown in different images. Place that somewhere on the cell.
14. Cytoskeleton: Use cotton thread to represent cytoskeleton. Cut about 20 strands of 8 inches long thread and glue them on the cell’s cross section, parallel and close to the cell membrane.
15. Colgi Vesicles or Lysosomes: Get 2 or 3 small foam balls and place them around the golgi on the cell’s cross section to represent the lysosomes. You may cut some of these balls in half and use a marker to place a few dots in their center to show enzymes that might be present in lysosomes.
16. Peroxisomes: Get a few more small foam balls and place them on the cell cross section. Color them different from lysosomes so you can distinguish them as peroxisomes.
17. Label all cell parts in your model.

Materials and Equipment:

List of material may vary based on your model design. You may make cell models using Styrofoam, paper, modeling clay or a combination of them. Following is a sample list of material.

1. Block of Styrofoam (18″ x 12″ x 1″)
2. One 3″ Styrofoam ball
3. Six 1′ Styrofoam balls
4. Set of acrylic paints (main colors)
5. One sheet of soft foam
6. Modeling clay
7. Papers and cardboard (or foam board)
8. cutting tools

Results of Experiment (Observation):

Experiments are often done in series. A series of experiments can be done by changing one variable a different amount each time. A series of experiments is made up of separate experimental “runs.” During each run you make a measurement of how much the variable affected the system under study. For each run, a different amount of change in the variable is used. This produces a different amount of response in the system. You measure this response, or record data, in a table for this purpose. This is considered “raw data” since it has not been processed or interpreted yet. When raw data gets processed mathematically, for example, it becomes results.

Following are some cell model samples.

Calculations:

No calculation is required.

Summary of Results:

Summarize what happened. This can be in the form of a table of processed numerical data, or graphs. It could also be a written statement of what occurred during experiments.

It is from calculations using recorded data that tables and graphs are made. Studying tables and graphs, we can see trends that tell us how different variables cause our observations. Based on these trends, we can draw conclusions about the system under study. These conclusions help us confirm or deny our original hypothesis. Often, mathematical equations can be made from graphs. These equations allow us to predict how a change will affect the system without the need to do additional experiments. Advanced levels of experimental science rely heavily on graphical and mathematical analysis of data. At this level, science becomes even more interesting and powerful.

Conclusion:

Using the trends in your experimental data and your experimental observations, try to answer your original questions. Is your hypothesis correct? Now is the time to pull together what happened, and assess the experiments you did.

Related Questions & Answers:

What you have learned may allow you to answer other questions. Many questions are related. Several new questions may have occurred to you while doing experiments. You may now be able to understand or verify things that you discovered when gathering information for the project. Questions lead to more questions, which lead to additional hypothesis that need to be tested.

Possible Errors:

If you did not observe anything different than what happened with your control, the variable you changed may not affect the system you are investigating. If you did not observe a consistent, reproducible trend in your series of experimental runs there may be experimental errors affecting your results. The first thing to check is how you are making your measurements. Is the measurement method questionable or unreliable? Maybe you are reading a scale incorrectly, or maybe the measuring instrument is working erratically.

If you determine that experimental errors are influencing your results, carefully rethink the design of your experiments. Review each step of the procedure to find sources of potential errors. If possible, have a scientist review the procedure with you. Sometimes the designer of an experiment can miss the obvious.

References:

List of References

http://academic.wsc.edu/faculty/jatodd1/ap1/ch3.html

http://www.tedankara.k12.tr/lise/zumreler/bioted/notes/CELL_dosyalar2/CELL2.htm

http://www.nigms.nih.gov/news/science_ed/lysme2.html

http://sun.menloschool.org/~cweaver/cells/e/lysosomes/

http://sun.menloschool.org/~cweaver/cells/e/nucleus/