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Transcript
Ch 7: A View of the Cell 7.1 - The Discovery of Cells Section 7.1 Inside This Section... The History of the Cell Theory The Cell Theory 2 Types of Microscopes 2 Basic Cell Types Section 7.1 The History of the Cell Theory The microscope was invented by Anton van Leeuwenhoek Dutch Scientist First Microbiologist Section 7.1 The History of the Cell Theory Section 7.1 The History of the Cell Theory The first person to see a cell (in cork) was Robert Hooke. Observed cells in Cork Section 7.1 The History of the Cell Theory Matthias Scleiden Concluded that all plants have Cells German Botanist Section 7.1 The History of the Cell Theory Theodore Schwann observed that animals were also composed of cells Section 7.1 The Cell Theory 3 main ideas: All living things are composed of one or more cells The Cell is the basic unit of organization of organisms All cells come from preexisting cells Section 7.1 The Light Microscope Uses light and lenses The Simple light Microscope used one lens and natural light (Leeuwenhoek) The Compound light microscope: Uses multiple lenses Magnifies up to 1500 times Section 7.1 The Electron Microscope Invented in the 1940s Uses a beam of electrons Magnifies up to 500,000 times Two Kinds: Scanning electron microscope (SEM): Scans the surface of cells. Transmission electron microscope (TEM): Allows for study of structures inside cells. Section 7.1 Microscope COmparison TEM SEM Section 7.1 Two Basic Cell Types Prokaryotes: Cells lacking internal membrane-bound structures Eukaryotes: Cells containing internal membrane-bound structures. The membrane-bound structures are called organelles. Contains a nucleus: organelle that manages cellular function. First observed by Robert Brown. Rudolf Virchow concluded that it was responsible for cell division. Section 7.1 Two Basic Cell Types Section 7.1 In Review... The History of the Cell Theory The Cell Theory 2 Types of Microscopes 2 Basic Cell Types Section 7.1 Animal Cell Structure Section 7.1 Plant Cell Structure Ch 7: A View of the Cell 7.2 - The Plasma Membrane Section 7.2 Inside This Section... Maintaining a Balance The Plasma Membrane The Structure of the Plasma Membrane Section 7.2 Maintaining a Balance The Plasma membrane is the boundary between the cell and it’s environment Needs to let the good stuff (e.g. nutrients) in and the bad stuff (waste) out The plasma membrane maintains homeostasis. Section 7.2 Maintaining a Balance Section 7.2 The Plasma Membrane Maintains Homeostasis: regulates internal environment [Good in (but not too much), Bad Out] Selective permeability: Allows some molecules into the cell and keeps some out. Some molecules can cross the plasma membrane (i.e. water). Others must go through channels (i.e. Na, Ca, etc) Section 7.2 Plasma Membrane Structure Composed of a phospholipid bilayer. A Lipid with a phosphate group attached Has only 2 fatty acid tails Forms a sandwich The phosphate group forms the polar head The fatty acid tails form the nonpolar tail Section 7.2 The Fluid Mosaic Model The membrane is fluid: It is flexible and phospholipids can move in the membrane like water in a lake. The membrane is mosaic: There are proteins embedded in the membrane that also move (like boats in the lake) Section 7.2 Other Components Cholesterol: Helps stabilize the plasma membrane, and prevents the phospholipids from sticking together. Transport Proteins: Proteins that span the entire membrane and form channels for specific molecules to enter and leave (like a door). Other Proteins and carbohydrates on the external surface: Helps with identification. Proteins on internal surface: Provides flexibility by attaching the plasma membrane to the cell’s internal structure. Section 7.2 Section 7.2 In Review... Maintaining a Balance The Plasma Membrane The Structure of the Plasma Membrane Ch 7: A View of the Cell 7.3 Eukaryotic Cell Structure Section 7.3 Inside This Section... Cellular Boundaries The Organelles Support And Locomotion Section 7.3 Cellular Boundaries Plasma membrane surrounds the cell In plants, fungi, most bacteria and some protists, the cell wall surrounds the plasma membrane Section 7.3 Cellular Boundaries Cell Wall Fairly rigid Provides support and protection Made up of the carbohydrate cellulose Has pores to allow molecules through Section 7.3 The Nucleus and Cell Control The Nucleus is the leader of the cell Gives directions for the making of proteins The master set of directions is in chromatin During cell division, chromatin condenses to form chromosomes. Section 7.3 The Nucleus and Cell Control Inside the nucleus there is also the nucleolus Makes ribosomes Ribosomes are sites where proteins and other enzymes are made, according to instructions from DNA Section 7.3 The Nucleus and Cell Control The Nuclear envelope is a double membrane that surrounds the nucleus. Made up of 2 phospholipid bilayers Contains small nuclear pores Section 7.3 The Cytoplasm • The Fluid inside the Cell Section 7.3 Assembly and Transport The endoplasmic reticulum: A series of highly folded membranes Where cellular chemical reactions take place Like a large workspace Section 7.3 Assembly and Transport Some parts have ribosomes attached (rough endoplasmic reticulum - RER) Others don’t (smooth endoplasmic reticulum – SER) Section 7.3 Assembly and Transport RER: Proteins made in the RER may: form part of the plasma membrane be released from the cell transported to other organelles Section 7.3 Assembly and Transport SER: involved in production and storage of lipids. Section 7.3 Assembly and Transport The Golgi apparatus: flattened system of tubular membranes and vesicles Modifies proteins Sorts and packages proteins It’s kind of like the post office: Sorts the mail and sends it to the right place Section 7.3 Vacuoles A vacuole is a sac surrounded by membrane Used for temporary storage of Food Enzymes Waste Plant cells usually have one large vacuole, animal cells have many smaller ones Section 7.3 Vacuoles Section 7.3 Lysosomes and Recycling Lysosomes are organelles that contain digestive enzymes They digest food particles, organelles and engulfed viruses or bacteria Can fuse with vacuoles and digest the contents. Can also digest cells that contain them. i.e. tadpole’s tail Section 7.3 Energy Transformers For all the cellular processes to happen, energy is needed Two organelles provide that energy: Choloroplasts (in plants) Mitochondria (in animals and plants) Section 7.3 Chloroplasts Chloroplasts are organelles that captures light energy and produces food to store for later Has a double membrane (like the nucleus) The inner membrane folds in to form stacks of membranous sacs called grana/thylakoids. Section 7.3 Chloroplasts In the thylakoid membrane there is the green pigment called Chlorophyll Traps light energy Gives leaves and stems their green color Section 7.3 Mitochondria Mitochondria produces energy in a form that can be used by the cell when necessary. Has an outer membrane and a highly folded inner membrane. Provides large surface area. Section 7.3 Support and Locomotion Cytoskeleton: forms the framework of the cell Maintains shape Composed of: Microtubules: thin hollow cylinders made of protein Microfilaments: thin, solid protein fibers Section 7.3 Support and Locomotion Cilia and flagella : Structures that aid in locomotion and feeding. Composed of pairs of microtubules, with a central pair surrounded by 9 additional pairs. Cilia are short, numerous, hair-like projections that move in a wavelike motion Flagella are longer projections, move in a whip-like motion. Section 7.3 In Review... Cellular Boundaries The Organelles Support And Locomotion