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Transcript
Cell Structure Eukaryotic Cell Bellwork What do we call the theory that describes the function of cells? Eukaryotic cells have this while Prokaryotic cells do not… True or False: Prokaryotic cells are generally larger than Eukaryotic Cells Objective You will know the functions of the major cell structures. The “Factory” Eukaryotic cells are in many ways like a factory. At first it looks like the eukaryotic cell is impossibly complex. But if you look close enough, you see patterns begin to emerge. There are many structures to the Eukaryotic cells that work together. These are called organelles which literally means “little organs.” Plant Cell Animal Cell Major Cell Types The nucleus The Cytoplasm Cytoplasm The Cytoplasm is the portion of the cell outside the nucleus. Cytoplasm is a thick solution that fills each cell and is enclosed by the cell membrane. It is mainly composed of water, salts, and proteins. In eukaryotic cells, the cytoplasm includes all of the material inside the cell and outside of the nucleus. The nucleus and Cytoplasm work together in the business of life. Nucleus In the same way that the main office controls a large factory, the nucleus is the control center of the cell The Nucleus is extremely important because it controls most cell process and contains the hereditary information of DNA. The DNA combines with protein to form Chromatin, which is found throughout the nucleus. The nucleus contains nearly all of the cell’s DNA and with it the coded instructions for making proteins and other important molecules. Nucleus The Nucleus is surrounded by a nuclear envelope which is composed of two membranes. The nuclear envelope is dotted with thousands of nuclear pores, which allow material to move into and out of the nucleus. Like messages, instructions, and blueprints moving in and out of a main office, a steady stream of proteins, RNA and other molecules move through the nuclear pores to and from the rest of the cell. Nucleus The granular material you can see in the nucleus is called the CHROMATIN. Chromatin is a complex of DNA and proteins that forms chromosomes within the nucleus of eukaryotic cells. Nucleus When a cell divides, chromatin condenses to form chromosomes. Chromosomes are thread-like structures located inside the nucleus of animal and plant cells. Each chromosome is made of protein and a single molecule of deoxyribonucleic acid (DNA). Passed from parents to offspring, DNA contains the specific instructions that make each type of living creature unique. Nucleus The small, dense region in the nucleus is the NUCLEOLUS. The Nucleolus is where the assembly of ribosomes begins. Ribosomes have one of the most important jobs in the cellular “factory.” Proteins are assembled on ribosomes. Ribosomes are small particles of RNA and protein found throughout the cytoplasm. They produce proteins by following coded instructions that come from the nucleus. Each ribosome, in its own way, is like a small machine in a factory, turning out proteins on orders that come from its “boss” which is the cell nucleus. Exit Ticket You will have the rest of the class period to finish your exit ticket. You will answer each question using complete sentences. Failure to do so will result in points be taken off. If you finish early, you may sit silently and wait for the bell to ring. Cell Structure Eukaryotic Cells Endoplasmic Reticulum (ER) Eukaryotic cells also contain an internal membrane system known as the endoplasmic reticulum or the ER. The ER is the site where lipid components of the cell membrane are assembled, along with proteins and other materials that are exported from the cell. Golgi Apparatus Proteins produced in the rough ER move next into an organelle called the Golgi apparatus. The function of the Golgi apparatus is to modify, sort, and package proteins and other materials from the endoplasmic reticulum for storage in the cell or secretion outside the cell. You can think of it like a customization shop, where the finishing touches are put on proteins before they are ready to leave the “factory.” From the Golgi apparatus, proteins are then “shipped” to their final destinations throughout the cell or outside of the cell. Lysosomes They are small organelles filled with enzymes. One function of lysosomes is the digestion, or breakdown, of lipids, carbs, and proteins into small molecules that can be used by the rest of the cell. They perform the vital process of removing “junk” that might otherwise accumulate and clutter up the cell. When lysosomes fail to function properly, you are more susceptible to certain diseases. Every factory needs a cleanup crew and that’s what Lysosomes do. Vacuoles Some kinds of cells contain saclike structures called vacuoles. They store materials such as water, salts, proteins, and carbs. In many plant cells there is a single, large central vacuole filled with liquid. The pressure of the central vacuole in these cells makes it possible for plants to support heavy structures such as leaves and flowers. Vacuoles are also found in some unicellular organisms and in some animals. Every factory needs a place to store things, and cells contain places for storage as well. Central Vacuole This is a picture of a paramecium which is a single-celled freshwater animal The paramecium has contractile vacuoles. They contract rhythmically and it pumps excess water out of the cell. The control of water content within the cell is just one example of an important process known as homeostasis. We will go more into that later though. Mitochondria All living things require a source of energy. Most cells get energy in one of two ways: from food molecules from the sun. With that in mind, note that nearly all eukaryotic cells, including plants, contain mitochondria. These are organelles that convert the chemical energy stored in food into compounds that are more convenient for the cell to use. Mitochondria are enclosed by two membranes-an outer membrane and an inner membrane. The inner membrane is folded up inside the organelle They are responsible for many of your characteristics and traits. Chloroplasts Plants and some other organisms contain chloroplasts. Chloroplasts are organelles that capture the energy from sunlight and convert it into chemical energy in a process called photosynthesis. Chloroplasts are the biological equivalents of solar power plants. Like mitochondria, chloroplasts are surrounded by two membranes. Inside the organelle are large stacks of other membranes, which contain the green pigment called chlorophyll. The chlorophyll absorbs the light that comes in and helps with the photosynthesis Cytoskeleton Eukaryotic cells are given their shape and internal organization by a supporting structure known as the cytoskeleton. The cytoskeleton is a network of protein filaments that helps the cell to maintain its shape. The cytoskeleton is also involved in movement. Microfilaments and microtubules are two of the principal protein filaments that make up the cytoskeleton. Every factory needs a form of transportation and a supporting structure. Microfilaments Microfilaments are threadlike structures made of a protein called actin. They form extensive networks in some cells and produce a tough, flexible framework that supports the cell. Microfilaments also help cells move. Microfilament assembly and disassembly is responsible for the cytoplasmic movements that allow cells, such as amoebas, to crawl along surfaces. Microtubules Microtubules are hollow structures made up of proteins known as tubulins. In many cells, they play critical roles in maintaining cell shape. Microtubules are also important in cell division, where they form a structure known as the mitotic spindle, which helps to separate chromosomes. Centrioles A centriole is a small set of microtubules arranged in a specific way. There are nine groups of microtubules. When two centrioles are found next to each other, they are usually at right angles. The centrioles are found in pairs and move towards the poles (opposite ends) of the nucleus when it is time for cell division. Lab: Making a Model Cell Procedure: You will be grouped into groups of 4. You will create a 3 dimensional model of a plant cell using the materials in the back. You will label each part of their cell clearly. They will then write a reflection on your model describing why you modeled it the way you did. This reflection will serve as your exit ticket. Lab Groups Group 1: Group 2: Group 3: Group 4: Group 5: Group 6:
