in 1663, an english scientist and inventor named robert ... · and the two parts move to opposite...

www.enchantedlearning.com/subjects/animals/cell/ http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/P/PlantCell.html http://library.thinkquest.org/5420/cellsplt.html http://www.youtube.com/watch?v=YrN9v5udaI8&NR=1 http://www.animalcells.net http://www.animalport.com/animal‐cells.html http://www.youtube.com/watch?v=Us9TPtWK3C8&feature=related http://www.biologycorner.com/lesson‐plans/cells/

In 1663, an English scientist and inventor named Robert Hooke made an amazing discovery. He studied a cork with a compound microscope (http://upload.wikimedia.org/wikipedia/commons/b/b1/Optical_microscope_nikon_alphaphot_%2B.jpg) and noticed row of row of small box liked spaces. Since he thought they looked like tiny rectangular rooms, he called the cells, which mean “small rooms”.

At approximately the same time, a Dutch businessperson named Antoni van Leeuwenhoek made another incredible discovery. Using a microscope he had designed on his own he studied a variety of materials including droplets of water from rain gutters and lakes, scraping from teeth and gums, and even blood. He was amazed to discover various micro-organisms. He watched these organisms swim, hop, and whirl through the fluids. Van Leeuwenhoek called these organisms animalcules, a term meaning “little animals”.

Alive Video: Students will have two class periods to create a video called “Alive”. Video must focus on nature and humanistic images that are alive.

Exit Slip: Why did you choose the images that you did for your Alive video?

Two Worldviews

According to the worldview of many First Nations and Metis peoples everything on Earth has Spirit flowing through it. Because of this Spirit, everything – people, animals, and even rocks – is considered to be alive. Many traditional elders believe that all beings are connected by Spirit and therefore we are all related. Spirit is the centre of life. Everything is interconnected through the natural cycles of the seasons and the cycles of people’s lives. Everything is part of the cycle of life. The worldview is described as holistic; people understand the world through observing what is present, not through trying to break objects into smaller parts. Elders share knowledge that is enough to allow young people to observe and come to their own understanding of the world. Through this worldview of connectedness, people naturally show respect for all life. Elders teach that all humanity has a responsibility to future generations to care for everything that is a part of Mother Earth. Activities that are not in balance with natural cycles, such as over-extraction and misuse of natural resources, hurt the Spirit that flows through all life.


Scientists define living things in a different way. The scientific worldview may be described as reductionist. This is the idea of breaking nature down one layer at a time until you arrive at the last layer. By breaking nature down one layer at a time, one develops a better understanding of nature as a whole.

As a result of the studies by people like Hooke and Van Leeuwenhoek, scientists came up with a list of characteristics to determine whether something is alive in the scientific worldview. These characteristics are:

1. Are made up of one or more than one cells 2. Respire (breath) 3. Require energy to live 4. Respond to stimuli in their environment 5. Grow and develop 6. Reproduce 7. Excrete (get rid of wastes)

Exit Slip Question: Name three characteristics in determining whether something is alive.

Furthermore, we must remember that the cell is the basic unit of life. Plant cells (unlike animal cells) are surrounded by a thick, rigid cell wall.

Plant Cells

http://www.cellsalive.com/cells/cell_model.htm


The following is a glossary of plant cell anatomy terms. amyloplast - an organelle in some plant cells that stores starch. Amyloplasts are found in starchy plants like tubers and fruits. ATP - ATP is short for adenosine triphosphate; it is a high-energy molecule used for energy storage by organisms. In plant cells, ATP is produced in the cristae of mitochondria and chloroplasts. cell membrane - the thin layer of protein and fat that surrounds the cell, but is inside the cell wall. The cell membrane is semipermeable, allowing some substances to pass into the cell and blocking others. cell wall - a thick, rigid membrane that surrounds a plant cell. This layer of cellulose fiber gives the cell most of its support and structure. The cell wall also bonds with other cell walls to form the structure of the plant.


centrosome - (also called the "microtubule organizing center") a small body located near the nucleus - it has a dense center and radiating tubules. The centrosomes is where microtubules are made. During cell division (mitosis), the centrosome divides and the two parts move to opposite sides of the dividing cell. Unlike the centrosomes in animal cells, plant cell centrosomes do not have centrioles. chlorophyll - chlorophyll is a molecule that can use light energy from sunlight to turn water and carbon dioxide gas into sugar and oxygen (this process is called photosynthesis). Chlorophyll is magnesium based and is usually green. chloroplast - an elongated or disc-shaped organelle containing chlorophyll. Photosynthesis (in which energy from sunlight is converted into chemical energy - food) takes place in the chloroplasts. christae - (singular crista) the multiply-folded inner membrane of a cell's mitochondrion that are finger-like projections. The walls of the cristae are the site of the cell's energy production (it is where ATP is generated). cytoplasm - the jellylike material outside the cell nucleus in which the organelles are located. Golgi body - (also called the golgi apparatus or golgi complex) a flattened, layered, sac-like organelle that looks like a stack of pancakes and is located near the nucleus. The golgi body packages proteins and carbohydrates into membrane-bound vesicles for "export" from the cell. granum - (plural grana) A stack of thylakoid disks within the chloroplast is called a granum. mitochondrion - spherical to rod-shaped organelles with a double membrane. The inner membrane is infolded many times, forming a series of projections (called cristae). The mitochondrion converts the energy stored in glucose into ATP (adenosine triphosphate) for the cell. nuclear membrane - the membrane that surrounds the nucleus. nucleolus - an organelle within the nucleus - it is where ribosomal RNA is produced. nucleus - spherical body containing many organelles, including the nucleolus. The nucleus controls many of the functions of the cell (by controlling protein synthesis) and contains DNA (in chromosomes). The nucleus is surrounded by the nuclear


membrane photosynthesis - a process in which plants convert sunlight, water, and carbon dioxide into food energy (sugars and starches), oxygen and water. Chlorophyll or closely-related pigments (substances that color the plant) are essential to the photosynthetic process. ribosome - small organelles composed of RNA-rich cytoplasmic granules that are sites of protein synthesis. rough endoplasmic reticulum - (rough ER) a vast system of interconnected, membranous, infolded and convoluted sacks that are located in the cell's cytoplasm (the ER is continuous with the outer nuclear membrane). Rough ER is covered with ribosomes that give it a rough appearance. Rough ER transport materials through the cell and produces proteins in sacks called cisternae (which are sent to the Golgi body, or inserted into the cell membrane). smooth endoplasmic reticulum - (smooth ER) a vast system of interconnected, membranous, infolded and convoluted tubes that are located in the cell's cytoplasm (the ER is continuous with the outer nuclear membrane). The space within the ER is called the ER lumen. Smooth ER transport materials through the cell. It contains enzymes and produces and digests lipids (fats) and membrane proteins; smooth ER buds off from rough ER, moving the newly-made proteins and lipids to the Golgi body and membranes stroma - part of the chloroplasts in plant cells, located within the inner membrane of chloroplasts, between the grana. thylakoid disk - thylakoid disks are disk-shaped membrane structures in chloroplasts that contain chlorophyll. Chloroplasts are made up of stacks of thylakoid disks; a stack of thylakoid disks is called a granum. Photosynthesis (the production of ATP molecules from sunlight) takes place on thylakoid disks. vacuole - a large, membrane-bound space within a plant cell that is filled with fluid. Most plant cells have a single vacuole that takes up much of the cell. It helps maintain the shape of the cell.


Animal Cells

http://www.cellsalive.com/cells/cell_model.htm

Explore: In partners, then have students share ideas.

1. How might the cells of a single-celled mycoplasma be different from the cells of a Blue Whale? How might they be similar?

2. How might your cells be different from the cells of another human, animal, or plant? How might they be similar?

The cell is the basic unit of life. Matthias Schleiden and Theodor Schwann concluded all organisms are made up of cells (or in some cases, a single cell). However, they did not know where cells came from. In 1855, another German scientist, Rudolf Virchow, stated that all cells come from existing cells, thus cells produce cells. From these statements the Cell Theory was created. The Cell Theory states:

1. All living things are composed of cells. 2. Cells are the basic unit of structure and function in living things. 3. All cells are produced from other living cells.

Some organisms are multicellular, meaning made up of more than two cells.

Other organisms are unicellular, made up of only one cell.

In your science journal jot down all the information you need to remember about cells.

Most cells are very small; most are invisible without using a microscope. Cells are covered by a cell membrane and come in many different shapes. The contents of a cell are called the protoplasm.


The following is a glossary of animal cell terms:

cell membrane - the thin layer of protein and fat that surrounds the cell. The cell membrane is semipermeable, allowing some substances to pass into the cell and blocking others. centrosome - (also called the "microtubule organizing center") a small body located near the nucleus - it has a dense center and radiating tubules. The centrosomes is where microtubules are made. During cell division (mitosis), the centrosome divides and the two parts move to opposite sides of the dividing cell. The centriole is the dense center of the centrosome. cytoplasm - the jellylike material outside the cell nucleus in which the organelles are located. Golgi body - (also called the Golgi apparatus or golgi complex) a flattened, layered, sac-like organelle that looks like a stack of pancakes and is located near the nucleus. It


produces the membranes that surround the lysosomes. The Golgi body packages proteins and carbohydrates into membrane-bound vesicles for "export" from the cell. lysosome - (also called cell vesicles) round organelles surrounded by a membrane and containing digestive enzymes. This is where the digestion of cell nutrients takes place. mitochondrion - spherical to rod-shaped organelles with a double membrane. The inner membrane is infolded many times, forming a series of projections (called cristae). The mitochondrion converts the energy stored in glucose into ATP (adenosine triphosphate) for the cell. nuclear membrane - the membrane that surrounds the nucleus. nucleolus - an organelle within the nucleus - it is where ribosomal RNA is produced. Some cells have more than one nucleolus. nucleus - spherical body containing many organelles, including the nucleolus. The nucleus controls many of the functions of the cell (by controlling protein synthesis) and contains DNA (in chromosomes). The nucleus is surrounded by the nuclear membrane. ribosome - small organelles composed of RNA-rich cytoplasmic granules that are sites of protein synthesis. rough endoplasmic reticulum - (rough ER) a vast system of interconnected, membranous, infolded and convoluted sacks that are located in the cell's cytoplasm (the ER is continuous with the outer nuclear membrane). Rough ER is covered with ribosomes that give it a rough appearance. Rough ER transports materials through the cell and produces proteins in sacks called cisternae (which are sent to the Golgi body, or inserted into the cell membrane). smooth endoplasmic reticulum - (smooth ER) a vast system of interconnected, membranous, infolded and convoluted tubes that are located in the cell's cytoplasm (the ER is continuous with the outer nuclear membrane). The space within the ER is called the ER lumen. Smooth ER transports materials through the cell. It contains enzymes and produces and digests lipids (fats) and membrane proteins; smooth ER buds off from rough ER, moving the newly-made proteins and lipids to the Golgi body, lysosomes, and membranes. vacuole - fluid-filled, membrane-surrounded cavities inside a cell. The vacuole fills with food being digested and waste material that is on its way out of the cell.


Videos on the Plant Cell

http://www.youtube.com/watch?v=uohe2V4yOzE http://www.youtube.com/watch?v=Yw6GDioafbU&feature=related (Plant Cell Project) http://www.youtube.com/watch?v=O_DmgfxBNP4&feature=related (Plant Cell Project) http://www.youtube.com/watch?v=2nqd9jYQEzw&feature=related (Plant Cell Project) http://www.youtube.com/watch?v=dtoM5T3UUPk&NR=1&feature=fvwp (Plant Cell Project)

Videos on Animal Cells http://www.youtube.com/watch?v=YM2X1c4K1x0&feature=related (Visual Tour) http://www.youtube.com/watch?v=Fzj6TRnXmps&feature=related http://www.youtube.com/watch?v=dA5RfoGiupM&feature=related http://www.youtube.com/watch?v=UesQLeXH8-c&feature=related (Project)

Using a Microscope

Introduction

Light microscopy or known as bright field microscope refers to the use of any kind of

microscope that uses visible light to observe specimens. A modern compound light microscope has

a series of lenses and uses visible light as its source of illumination. With a compound light

microscope, we can examine very small specimens as well as some of their fine detail. A series of

finely ground lenses forms a clearly focused image that is many times larger than the specimen

itself. This magnification is achieved when light rays from an illuminator, the light source, pass

through a condenser which has lenses that direct the light through the specimen. From here light


rays pass into objective lenses, the lenses closest to the specimen. The image of the specimen is

magnified again by the ocular lens or eye piece.

We can calculate the total magnification of a specimen by multiplying the objective lens

magnification (power) by the ocular lens magnification (power). Most microscopes used in

microbiology have several objective lenses, including 10x (low power), 40x (high power), and 100x

(oil immersion, which described shortly). Most ocular lenses magnify specimens by a factor of 10.

Multiplying the magnification of a specific objective lens with that of the ocular, we see that the total

magnifications would be 100x for low power, 400x for high power and 1000x for oil immersion. Some

compound light microscopes can achieve a magnification of 2000x with the oil immersion lens.

Resolution (also called resolving power) is the ability of the lenses to distinguish fine detail

and structure. Specifically, it refers to the of the lenses to distinguish between two points a specified

distance apart. For example, if a microscope has a resolving power of 0.4 nm apart. A general

principle of microscopy is that the shorter the wavelength of light used in the instrument, the greater

the resolution. The white light used in a compound light microscope has a relatively long wavelength

and cannot resolve structures smaller than about 0.2 µm. This fact and other practical considerations

limit the magnification achieved by even the best compound light microscopes to about 2000x.

To obtain a clear, finely detailed image under a compound light microscope, specimens must

be made to contrast sharply with their medium (substance in which they are suspended). To attain

such contrast, we must change the refractive index of specimens from that of their medium. The

refractive index is a measure of the light bending ability of a medium. To achieved high magnification

(1000x) with good resolution the objective lens must be small. To preserve the direction of light rays

at the higher magnification, immersion oil is placed between the glass slide and the oil immersion

objective lens. The oil has the same effect as increasing the objective lens diameter; therefore it

improves the resolving power of lenses. Under usual operating conditions, the field of vision in a


compound light microscope is brightly illuminated. By focusing the light, the condenser produces a

brightfield illumination.


Figure 1.1 : The path of light in the compound microscope Figure 1.2 : Path light through a compound light microscope. Besides 10x, eyepieces (ocular) are available in 15 – 30x. 3

Figure 1.3 : Immersion oil. Immersion is used to prevent the loss of light

that results from refraction. The focusing of as much light as possible adds to the clarity of the

image. Immersion oil may also be added between the top of the condenser and the bottom of the

slide to eliminate another site for refraction.

Two Basic Types of Cells All cells fall into one of the major classifications, prokaryote or eukaryotes. Prokaryotic Cells

Prokaryotes are evolutionarily ancient. They were here first and for billions of years were the only

form of life. And even with the evolution of more complex eukaryotic cells, prokaryotes are

supremely successful. All bacteria and bacteria-like Archaea are prokaryotic organisms. Their


genetic material is naked within the cytoplasm, ribosomes their only type of organelle. Prokaryote

are most always single-celled, except when they exist in colonies, reproduced by means of binary

fission, duplicating their genetic material and then essentially splitting to form two daughter cells

identical to parent. 4

Online Microscope - http://www.udel.edu/biology/ketcham/microscope/

Virtual Microscope Lab - Cheek Cells

Introduction: If you missed the microscope lab we did in class, you will need to make it up by using a "virtual microscope" which can be accessed on the internet. The virtual microscope is a little more complicated than the microscope we used in the lab, but it will not be difficult to use. In class, we obtained cheek cells by scraping the inside of the mouth with a toothpick and then rubbing the toothpick on a drop of water with blue stain. The blue helps you see the cells which are normally a clear color. The virtual lab begins at the step where you place the slide on the microscope page.

Print this page or write answers on notebook paper.

Access the Virtual Microscope at http://www.udel.edu/biology/ketcham/microscope/ Click on the link that says "the virtual scope"

1. Familiarize yourself with the microscope, run the tutorial and examine the parts you will be working with.

2. View the slide labeled cheek smear. Sketch the image at Scanning, Low and High Power. LABEL on high power the CELL MEMBRANE, CYTOPLASM, and NUCLEUS.

Scanning (4) Low (10) High (40)


3. Go to google and type "cheek cells" into the search box. Click on "images" to see all the images google has found on the web showing cheek cells (there should be hundreds).

What do all of these images have in common?

How do the cells vary from one picture to the next (how are they different)?

4. Why are the google images of cells different colors? What is the natural color of a cheek cell?

5. Use the internet or your textbook to define or describe each of the following terms that relate to the cell.

eukaryote

nucleus

cell membrane

cytoplasm

6. Keeping in mind that the mouth is the first site of chemical digestion in a human.Your saliva starts the process of breaking down the food you eat.Keeping this in mind, what organelle do you think would be the most numerous inside the cells of your mouth? (Hint: what organelle is responsible for breaking things down and digesting?)


The Human Cheek Cell Name __________________________

1. List the 3 parts of the Cell Theory

_____________________________________

_____________________________________

_____________________________________

2. Describe or define each of the following

--cell membrane _____________________________

--cytoplasm _________________________________

--nucleus ___________________________________ --organelle ________________________________

Procedure: 1. Put a drop of methylene blue on a slide. Caution: methylene blue will stain clothes and skin. 2. Gently scrape the inside of your cheek with the flat side of a toothpick. Scrape lightly. 3. Stir the end of the toothpick in the stain and throw the toothpick away. 4. Place a coverslip onto the slide 5. Use the SCANNING objective to focus. You probably will not see the cells at this power. 6. Switch to low power. Cells should be visible, but they will be small and look like nearly clear purplish blobs. If you are looking at something very dark purple, it is probably not a cell 7. Once you think you have located a cell, switch to high power and refocus. (Remember, do NOT use the coarse adjustment knob at this point)

3. Sketch the cell at low and high power. Label the nucleus, cytoplasm, and cell membrane. Draw your cells to scale.

Low Power High Power


5. Why is methylene blue necessary?

6. The light microscope used in the lab is not powerful enough to view other organelles in the cheek cell. What parts of the cell were visible.

7. List 2 organelles that were NOT visible but should have been in the cheek cell.


8. Is the cheek cell a eukaryote or prokaryote? How do you know?

9. Keeping in mind that the mouth is the first site of chemical digestion in a human. Your saliva starts the process of breaking down the food you eat. Keeping this in mind, what organelle do you think would be numerous inside the cells of your mouth?


Plant Cells --Internet Lab--

Introduction: If you missed the microscope lab we did in class, you will need to make it up by using a "virtual microscope" which can be accessed on the internet. The virtual microscope is a little more complicated than the microscope we used in the lab, but it will not be difficult to use.

Access the Virtual Microscope at http://www.udel.edu/biology/ketcham/microscope/ Click on the link that says "the virtual scope"

1. Familiarize yourself with the microscope, run the tutorial and examine the parts you will be working with.

2. View the slide onion. Sketch the image at Scanning, Low and High Power. LABEL on high power the CELL MEMBRANE, CYTOPLASM, and NUCLEUS.

Scanning (4)

Low (10) High (100)


Plant Cell Lab

Purpose: Students will observe plant cells using a light microscope. Two cells will be observed, one from the skin of an onion, and the other from a common aquarium water plant (anacharis). Students will compare both types of cells. See also: Plant Cell Lab Makeup, which utilizes web resources to complete lab guide.

Prelab Questions

1. What is the function of chloroplasts?

2. Name two structures found in plant cells but not animal cells.

3. Name three structures found in plant cells AND in animal cells.

4. What structure surrounds the cell membrane (in plants) and gives the cell support.


Procedure: Go to www.biologycorner.com/worksheets/plantcells.html which contains images of cells as they were viewed in the lab. You will use these images to complete this worksheet.

Part A - Onion Cells

Obtain a prepared slide of onion cells or prepare one yourself. View under the microscope and sketch the cells at each magnification. Label the cells as they appear under high power.

Part B - Elodea Cells

View a prepared slide of elodea (anacharis), which is an aquarium plant. As the slide warms from the light of the microscope, you may see the chloroplasts moving, a process called cytoplasmic streaming.


Post Lab Questions

1. Describe the shape and the location of chloroplasts.

2. Why were no chloroplasts found in the onion cells? (hint: think about where you find onions)

3. Which type of cell was smaller - the onion cells or the elodea cells?

4. Fill out theVenn Diagram below to show the differences and similarities between the onion cells and the elodea cells.


Comparing Plant and Animal Cells

Problem: How are plant and animal cells alike? How are they different?

Procedure: In this lab, you will view cells from your cheek (animal cells) and cells from elodea, which is a water plant. Careful observation should reveal similarities and differences between the cells.

Cheek Cells

Gently scrape a toothpick over the inside of your cheek and swirl it in a drop of methylene blue to stain the cells (otherwise they will be clear and difficult to see). You are looking for light colored blobs with dark spots in them. Perfect circles with black outlines are airbubbles. Don't sketch those. Sketch the cheek cells under low and high power. Make sure you are drawing your cells to SCALE - that is, the size of your drawing should reflect the size that you view them in the microscope.


1. Identify the NUCLEUS on your drawing.

2. Identify the CELL MEMBRANE on your drawing.

3. Identify the CYTOPLASM (area) on your drawing.

Elodea Cells

Cut a small peice of elodea leaf and prepare a wet mount. When you are looking for cells, you should find a lot more than you found with the cheek cells, and it will resemble a green brick wall. Sketch your cells under low and high power, also paying attention to scale. The nucleus of these cells will not be visible but you should see many chloroplasts within each cell. Plant cells also have a rigid cell wall, outside the cell membrane. The Cell wall should also be visible.



1. Identify the CHLOROPLASTS on your drawing.

2. Identify the CELL WALL on your drawing.

3. Identify the CYTOPLASM (area) on your drawing.

4. Identify the CENTRAL VACUOLE on your drawing.

Analysis - Venn Diagram

Create a Venn Diagram of plant and animal cells. Remember, things that they have in common go into the overlapping area, things that are different go in the non-overlapping area.


Cell City Analogy Name:_________________________

In a far away city called Grant City, the main export and production product is the steel widget. Everyone in the town has something to do with steel widget making and the entire town is designed to build and export widgets. The town hall has the instructions for widget making, widgets come in all shapes and sizes and any citizen of Grant can get the instructions and begin making their own widgets. Widgets are generally produced in small shops around the city, these small shops can be built by the carpenter's union (whose headquarters are in town hall).

After the widget is constructed, they are placed on special carts which can deliver the widget anywhere in the city. In order for a widget to be exported, the carts take the widget to the postal office, where the widgets are packaged and labeled for export. Sometimes widgets don't turn out right, and the "rejects" are sent to the scrap yard where they are broken down for parts or destroyed altogether. The town powers the widget shops and carts from a hydraulic dam that is in the city. The entire city is enclosed by a large wooden fence, only the postal trucks (and citizens with proper passports) are allowed outside the city.

Match the parts of the city (underlined) with the parts of the cell.


** Create your own analogy of the cell using a different model. Some ideas might be: a school, a house, a factory, or anything you can imagine**

1. Mitochondria _____________________________________________

2. Ribosomes _____________________________________________

3. Nucleus _____________________________________________

4. Endoplasmic Reticulum _____________________________________________

5. Golgi Apparatus _____________________________________________

6. Protein _____________________________________________

7. Cell Membrane _____________________________________________

8. Lysosomes _____________________________________________

9. Nucleolus _____________________________________________


Cells Research and Design

Part A: Research - go to each of the following sites and complete the activities listed. Check the box for each activity.

Site 1: http://www.biology.ualberta.ca/facilities/multimedia/ (Go to link on Cell biology)

Animal Cell Mix & Match Plant Cell Mix & Match

Comparing Prokaryotic and Eukaryotic Cells

Site 2: www.cellsalive.com

animal cell model plant cell model bacteria cell model

Complete the table based on what you have learned about the cell.

Found In (check ) Function Sketch

Animal Plant Bacteria

Nucleus

Chromatin (DNA)

Lysosome

Mitochondria

Flagella

Smooth ER

Rough ER

Golgi Apparatus


Cytoplasm

Ribosome

Nucleolus

Cell Wall

Vacuole

Chloroplast

Part B: Build Your Own Cell Model

Using image editing software (Microsoft Paint, Photoshop, etc) create your own color diagram of the cell. Use the following guidelines. Turn in your model using a flash drive or email.

There are also several online image editors: Piknik ( http://www.picnik.com/app ) | Pixlr ( http://www.pixlr.com/editor/ ) Sumopaint ( http://www.sumopaint.com/home/ ) | Artpad ( http://artpad.art.com/artpad/painter/ )

Identify whether your cell is a plant or an animal (no bacteria) All relevant cell organelles and parts must be represented and labeled You may NOT cut/paste other models you might find on the web, but you're welcome to use them

for ideas.

Grading Rubric

Name 4 3 2 1 0 Research Phase ‐ table completed

Design - Labels (accurate, easy to read) Design -Complexity (number of organelles represented, effort) Design -Accuracy (organelles look as they should, positioning) Design - Effort, overall appearance

TOTAL


http://www.biologycorner.com/lesson‐plans/cells/

How Substances Move In and Out of Cells

In order for our body to survive our cells need to bring water, gases, and food inside itself. These provide

energy that is needed to survive. At the same time, our body and cells must remove waste products.

This does not only happen in humans, but with every living organism. The cell membrane is what

controls this process to occur. The process of the cell membrane allowing substances to enter the cell is

called “diffusion”.

Conduct the mini experiments on page 31.

The Cell Membrane and Diffusion

Scientists believe that everything that is made up of particles and that these particles are in constant

motion. So when you drop food colouring into the water, the food colouring particles collided with each

other and the particles of water. When we first dropped the food colouring there were many collision

since there was a large concentration of food colouring. With these collisions, the food colouring was

allowed to separate since food colouring particles were bumping off each other. This allowed the food

colouring to spread out evenly within the beaker. The process of the food colouring moving from an

area of high concentration to an area of lower concentration is called diffusion. So simply put, diffusion

is a “balancing out” process in allowing even concentration. Even when the concentration levels of a

substance are equal, particles are still moving within the solution; however, our eye just can’t see the

motion.

Selectively Permeable Membranes

Many substances move in and out of a cell through diffusion. The cell membrane acts like a wall with

many “tiny” openings. These openings are small enough to keep the cell’s cytoplasm and its contents

inside. They also keep the substances in the cell’s external environment out. Therefore, substances can

pass in and out through the cell membrane. So the cell membrane will allow some substances to pass

though it, but not all. Scientists say that this is selectively permeable.

One of those substances that can pass through would be oxygen. Most cells need oxygen to perform

cellular respiration. The physical properties of oxygen allow them to pass though the cell membrane.

This movement of oxygen has by diffusion, and it naturally occurs. That is because the concentration of

oxygen is usually higher outside the cell membrane than inside. Oxygen will simply diffuse into the cell.

The cell does not have to do anything.


The Cell Membrane and Osmosis

Water is another substance that diffuses through the cell membrane. The amount of water inside a cell

must remain fairly constant. If the water concentration inside the cell becomes too low, then water from

outside the cells diffuses inside the cell. If the water level inside the cell becomes too high, then

naturally water will diffuse out of the cell.

The diffusion of water in and out of the cell is essential for the existence of the cell. For this reason,

scientists give this process a special name, “osmosis”. Osmosis is the process of diffusion of water

particles through a selectively permeable membrane. The water particles move from an area of high

concentration to an area of lower concentration.

Exit Slip: How does the process of diffusion work in a cell?


Cell Specialization

Multicellular Organisms Have Specialized Cells

in 1663, an english scientist and inventor named robert ... · and the two parts move to opposite...

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