Teacher Preparation Notes Prior to completing this activity, students should have a basic introduction to cells. This introduction should include the following points: • • • • Cells are the basic functional and structural unit of life. Cells have three basic parts – plasma membrane, nucleus, and cytoplasm. Organelles are the cell’s “machinery”. Interdependence of these parts should be stressed. This basic introduction could be accomplished by o A short reading assignment o A short video o A short lecture in class Setup: Students can work independently but this activity is ideal for groups of two or three. Each student should have their own worksheet and should complete it themselves while working with the team. If there are enough models in your classroom for each group of three to have a human cell model, then each group can work at a lab table to complete the activity. Additionally, each group will need access to a skeletal muscle cell and a neuron. Even if you only have one of each, the groups can take turns making their observations. If there aren’t enough models, you can set up “stations” with models at some stations and pictures at other stations. These pictures should be unlabeled human cells, preferable drawings. Student teams can move from station to station. If students struggle with the questions, I try to provide guidance but stop short of answering it for them. I assure them that we will go over the answers at the end. Go over answers with students: Once students have completed the pages, I go over the assignment with them. I might ask each group to present an organelle and answer the questions for the class, interjecting as necessary. Another suggestion is to assign each student team an organelle to present to the class the following class period. Human Cell Organelles Name: ____________ Date: _____________ Resources needed: • Animal cell model (generic) • Other human cell models – skeletal muscle and neuron Using the models and images provided, answer the questions below regarding cell organelles. Define organelle. How is an “organelle” different from an “organ”? What is the shape of the human cell model? Sketch it below. Do you think every animal cell is this shape? Plasma Membrane Examine the model of the human cell and identify the plasma membrane. What is the purpose of the plasma membrane? Nucleus Examine the model of the human cell and identify the nucleus. Sketch the nucleus in the box below. How many nuclei are present in most human cells? Could a cell have more than once nucleus? Can you give an example? How is the nucleus separated from the rest of the cell? What do you notice about this “nuclear envelope”? What is the shape of the nucleus? What is located in the nucleus of a cell? List any structures here: What is the function of the nucleus? Nucleoli Examine the model of the human cell and identify any nucleoli. What is the singular of nucleoli? Do cells always have the same number of nucleoli? Are the nucleoli always found in the nucleus? What is the function of nucleoli? Rough Endoplasmic Reticulum Examine the model of the human cell and identify the rough endoplasmic reticulum. Sketch the rough endoplasmic reticulum in the box below. How would you describe the shape of this organelle? Is this organelle connected to the nucleus at all? What makes it “rough”? What is the function of the rough endoplasmic reticulum? What would you conclude about a cell that had a lot of rough endoplasmic reticulum compared to one that didn’t have as much? Ribosomes Examine the model of the human cell and identify the ribosomes. Are ribosomes only associated with rough endoplasmic reticulum? What is the function of ribosomes? Smooth Endoplasmic Reticulum Examine the model of the human cell and identify the smooth endoplasmic reticulum. Sketch the smooth endoplasmic reticulum in the box below. How would you describe the shape of this organelle? Is this organelle connected to the nucleus at all? What makes it “smooth”? List some of the functions of the smooth endoplasmic reticulum? What would you conclude about a cell that had a lot of smooth endoplasmic reticulum compared to one that didn’t have as much? Golgi Apparatus Examine the model of the human cell and identify the Golgi apparatus. Sketch the Golgi apparatus in the box below. Do cells have one or many? How would you describe the shape of this organelle? Specifically, how is the shape of the Golgi apparatus different from the endoplasmic reticulum? What organelle is closest (in proximity) to the Golgi apparatus? What is the function of the Golgi apparatus? Mitochondria Examine the model of the human cell and identify mitochondria. Sketch mitochondria in the box below. Do cells have one or many mitochondria? How would you describe the shape of mitochondria? What do you notice about the inside of mitochondria? What is the function of mitochondria? What would you conclude about a cell that had many mitochondria compared to one that didn’t have as many? Lysosomes Examine the model of the human cell and identify lysosomes. Do cells have one or many lysosomes? How would you describe the shape of lysosomes? What is the function of lysosomes? What would you conclude about a cell that had many lysosomes compared to one that didn’t have as many? Peroxisomes Examine the model of the human cell and identify peroxisomes. Do cells have one or many peroxisomes? How would you describe the shape of peroxisomes? What is the function of peroxisomes? Cytoskeleton Is the cytoskeleton visible in your cell model? If not, consult the images in your textbook. The cytoskeleton is composed of three different types of “rods”. List them from “thinnest” to “thickest” 1. 2. 3. Centrosomes and Centrioles Examine the model of the human cell and identify the centrosome with paired centrioles. Sketch centrioles in the box below. Which cytoskeletal type is present in centrioles? Describe the structure of the centrioles? What is the function of the centrioles? Cellular Extensions Are cilia, flagella and microvilli visible in your cell model? If not, consult other images. What is the difference in structure between the three cellular extensions? List the function of each of the cellular extensions. Where in the human body do you find cilia? What is the only human cell that has a flagella? Where in the human body do you find microvilli? Skeletal Muscle Cell (Fiber) List three ways that the skeletal muscle cell is different from other cells you have observed? 1. 2. 3. A skeletal muscle cell is called a “fiber”? Why do you think this is? You will notice long rods inside the cell. What are these? What are their purpose? Do you see a nucleus in the muscle fiber? How many? What is unique about their location? Can you identify mitochondria in the muscle fiber? Why might a skeletal muscle need many mitochondria? Neuron (Nerve cell) List three ways that the neuron is different from other cells you have observed? 1. 2. 3. What is unique about the shape of the neuron? A neuron has three main areas: cell body, dendrites and the axon. List some organelles in the cell body. Do neurons have mitochondria? Where are they located? Human Cell Organelles Name: ______________ Date: ______________ Resources needed: • Animal cell model (generic) • Other human cell models – skeletal muscle, and neuron Using the models and images provided, answer the questions below regarding cell organelles. Define organelle. “little organs”; specialized cellular compartments inside of cells; each performing its own job ”? How is an “organelle” different from an “organ”? a part of the body formed from tissues; a higher level of organization in the hierarchy of life What is the shape of the human cell model? Sketch it below. Human (animal) cell models tend to be spherical in shape, though human cells have a variety of shapes depending on their location. This is a great opportunity to explain that many models and pictures show a “generic” cell. Do you think every animal cell is this shape? No. Plasma Membrane Examine the model of the human cell and identify the plasma membrane. What is the purpose of the plasma membrane? It is semi-permeable to regulate which substances can enter and exit the cell. There is much more detail about the plasma membrane that isn’t addressed here but students will explore this when they study osmosis and diffusion. Nucleus Examine the model of the human cell and identify the nucleus. Sketch the nucleus in the box below. How many nuclei are present in most human cells? One Could a cell have more than once nucleus? Can you give an example? Some human cells have more than one nuclei (some bone cells and some liver cells) How is the nucleus separated from the rest of the cell? It is separated by a nuclear envelope. What do you notice about this “nuclear envelope”? It has pores, allowing it to be permeable. What is the shape of the nucleus? Nuclei are spherical in most models. However, nuclei can take on different shapes in a variety of cells. What is located in the nucleus of a cell? List any structures here: Nucleoli DNA (Chromatin, chromosomes) What is the function of the nucleus? “control center of the cell”; contains the genetic material; dictates protein synthesis Nucleoli Examine the model of the human cell and identify any nucleoli. What is the singular of nucleoli? Nucleolus Do cells always have the same number of nucleoli? No. Typically, there are one or two but there can be more. Are the nucleoli always found in the nucleus? Yes. What is the function of nucleoli? Synthesizes rRNA, which forms the ribosomes Rough Endoplasmic Reticulum Examine the model of the human cell and identify the rough endoplasmic reticulum. Sketch the rough endoplasmic reticulum in the box below. How would you describe the shape of this organelle? Membranous system snaking through the cytoplasm Is this organelle connected to the nucleus at all? Yes, it is continuous with the nuclear envelope. What makes it “rough”? Studded with ribosomes. What is the function of the rough endoplasmic reticulum? Modify proteins, stores protein in vesicles to be transported to the Golgi apparatus; synthesizes phospholipids What would you conclude about a cell that had a lot of rough endoplasmic reticulum compared to one that didn’t have as much? Cells with a lot of Rough ER tend to synthesize and ultimately, secrete a lot of protein Ribosomes Examine the model of the human cell and identify the ribosomes. Are ribosomes only associated with rough endoplasmic reticulum? No, ribosomes can be free in the cytoplasm as well. What is the function of ribosomes? Protein synthesis Smooth Endoplasmic Reticulum Examine the model of the human cell and identify the smooth endoplasmic reticulum. Sketch the smooth endoplasmic reticulum in the box below. How would you describe the shape of this organelle? Membranous system of sacs and tubules; similar to Rough ER Is this organelle connected to the nucleus at all? No. What makes it “smooth”? lacks ribosomes List some of the functions of the smooth endoplasmic reticulum? Lipid synthesis; detoxification; calcium ion storage What would you conclude about a cell that had a lot of smooth endoplasmic reticulum compared to one that didn’t have as much? It is a cell that is responsible for detoxification (i.e. liver cell); modified Smooth ER is found in muscle cells to store calcium. Golgi Apparatus Examine the model of the human cell and identify the Golgi apparatus. Sketch the Golgi apparatus in the box below. Do cells have one or many? Usually one How would you describe the shape of this organelle? Membranous tubule but with bulbous ends Specifically, how is the shape of the Golgi apparatus different from the endoplasmic reticulum? Has bulbous ends where vesicles pinch off. What organelle is closest (in proximity) to the Golgi apparatus? Rough ER What is the function of the Golgi apparatus? Receives vesicles from the Rough ER; packages protein for secretion or to incorporate into the plasma membrane; forms lysosomes Mitochondria Examine the model of the human cell and identify mitochondria. Sketch mitochondria in the box below. Do cells have one or many mitochondria? Yes, many more than one. How would you describe the shape of mitochondria? Shaped like a bean (kidney) What do you notice about the inside of mitochondria? Double membrane; inner membrane is highly folded What is the function of mitochondria? To produce ATP (energy). What would you conclude about a cell that had many mitochondria compared to one that didn’t have as many? Requires a lot of energy production, like muscle cells (compared to a cell that might store sugar or fat) Lysosomes Examine the model of the human cell and identify lysosomes. Do cells have one or many lysosomes? Generally, many more than one. How would you describe the shape of lysosomes? Spherical; vesicles that have pinched off from the Golgi apparatus What is the function of lysosomes? Filled with digestive enzymes; digestion of ingested food, bacteria, and old/damaged organelles What would you conclude about a cell that had many lysosomes compared to one that didn’t have as many? It might be an immune cell. Peroxisomes Examine the model of the human cell and identify peroxisomes. Do cells have one or many peroxisomes? more than one. How would you describe the shape of peroxisomes? Spherical, but do not form from Golgi apparatus; Similar in shape to lysosomes What is the function of peroxisomes? Detoxification Cytoskeleton Is the cytoskeleton visible in your cell model? If not, consult the images in your textbook. The cytoskeleton is composed of three different types of “rods”. List them from “thinnest” to “thickest” 1. Microfilament – supports cell’s shape; cell movements 2. Intermediate filament – reinforce cell’s shape; anchors organelles 3. Microtubule – organelle movement; composes centrioles Centrosomes and Centrioles Examine the model of the human cell and identify the centrosome with paired centrioles. Sketch centrioles in the box below. Which cytoskeletal type is present in centrioles? Microtubules Describe the structure of the centrioles? Paired; cylinder-like; each has nine microtubules What is the function of the centrioles? Organizes spindle during mitosis Cellular Extensions Are cilia, flagella and microvilli visible in your cell model? If not, consult other images. What is the difference in structure between the three cellular extensions? Cilia are short extensions composed of microtubules; Flagella are longer and usually singular Microvilli are extensions of the plasma membrane to increase surface area. List the function of each of the cellular extensions. Cilia - usually work with other cilia to propel substances. Flagella – used to propel the cell (i.e. sperm cells) Where in the human body do you find cilia? Example: lining the trachea What is the only human cell that has a flagella? Sperm cell Where in the human body do you find microvilli? Lining of the small intestines Skeletal Muscle Cell (Fiber) List three ways that the skeletal muscle cell is different from other cells you have observed? 1. Long cylindrical cell (not round like many models) 2. Contains myofibrils 3. Multinucleate A skeletal muscle cell is called a “fiber”? Why do you think this is? Because it is a long cylindrical cell, it looks more like a long fiber. Also, fibers are much larger than other human cells You will notice long rods inside the cell. What are these? Myofibrils, composed of actin and myosin proteins What are their purpose? contraction Do you see a nucleus in the muscle fiber? How many? Yes, muscle fibers have many nuclei. What is unique about their location? They are located just beneath the plasma membrane (sarcolemma) Can you identify mitochondria in the muscle fiber? Yes, students should be able to see mitochondria easily. Why might a skeletal muscle need many mitochondria? High energy demands of skeletal muscle cells. Neuron (Nerve cell) List three ways that the neuron is different from other cells you have observed? 1. Shape is different with a many projections. 2. Can be very long 3. Conduct nervous impulses What is unique about the shape of the neuron? Many projections rather simply being a round cell. A neuron has three main areas: cell body, dendrites and the axon. List some organelles in the cell body. Nucleus, ribosomes and rough endoplasmic reticulum (Nissl bodies), mitochondria, Golgi apparatus, and neurofibrils Do neurons have mitochondria? Where are they located? Yes, many. Cell body and the axons.
