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CELLS & the ORGANELLES Prokaryote vs. Eukaryote Animal vs. Plant Early Microscopes • Robert Hooke (1665) Coined the term “cell” (Why?) looking at cork, he saw little boxes Is cork alive? • Anton von Leeuwenhoek (1674) saw living cells in pond water Cell Discoveries • Matthias Schleiden (1838) Plants are made of cells • Theodor Schwann (1839) Animals are made of cells • Rudolf Virchow (1855) Saw dividing cells new living cells come from pre-existing cells The Cell Theory 1. All living things made of cells. 2. Cell are the basic unit of structure & function for life. 3. Cells can only arise from pre-existing living cells Specialization • Unicellular organisms living organisms that are only ONE cell – Examples: bacteria, algae, protists, yeast • Multicellular organisms any organism that is made of more than one cell – Evolved later Kingdoms and Domains Three Domain System Bacteria Archaea Eukarya Six Kingdom System Bacteria Archaea (based on rRNA evidence) (based on rRNA evidence) Protista Fungi Plantae Animalia Traditional Five Kingdom System Monera Protista Fungi Plantae Animalia Humans = 5% Prokaryote vs. Eukaryote All cells have a membrane, cytoplasm, DNA & ribosomes • Prokaryotic Cells – DNA not bound by a membrane… no “true nucleus” – Usually smaller, simple – No membrane bound parts (organelles) – Ex: bacteria • Eukaryotic Cells – Membrane bound nucleus – Larger, complex, internal organization – Have internal membrane bound structures – Ex: you, plants, algae Can unicellular organisms be eukaryotic? What does that mean? Do prokaryotes have DNA? What is an example of a prokaryote? Are prokaryotes considered to be alive? Why do we need to understand cells? Each organelle has a specific job that needs to be performed. The more we understand their jobs, the better we can understand life. Basic Cell Structures • Cell membrane • Nucleus -nucleolus -nuclear envelope • Cytoplasm Organelles • Very small size • Can only be observed under a microscope • Have specific functions • Found throughout cytoplasm • Include: Cytoplasm, Nucleus, ribosomes, endoplasmic reticulum, Golgi apparatus, lysosomes, vacuoles, mitochondria, chloroplasts (plants only), cytoskeleton, centrioles (Animal only) The Nucleus: Control center of the cell, houses genetic material Nucleolus • Is a small dense region in the nucleus • Makes ribosomes, which make proteins RIBOSOMES • Free floating in cytoplasm or • Attached to ER • “reads” RNA code from DNA to assemble proteins • “protein factory” ENDOPLASMIC RETICULUM • Internal membrane • Lipid parts of the cell membrane made here • Makes proteins etc. for shipment out of cell • Can be “Rough” or Smooth GOLGI APPARATUS • Modifies, sorts, packages proteins and other products • Destination – storage in cell – export out of cell • Customizes • Adds lipids, carbs to protein LYSOSOMES • Small, enzyme-filled organelles • Digests material for use or disposal • Tay Sachs disease has dysfunctional lysosomes in neural cells which allows fats to accumulate MITOCHONDRIA • Convert food into usable energy • Have an outer & inner membrane • Has its own DNA! – Inherited from your mom CHLOROPLASTS • Capture sunlight & convert it to energy – Photosynthesis • Have 2 membranes • Contain the green pigment chlorophyll • Has its own DNA! VACUOLES • Stores materials • Water, salts, protein, carbs • Largest in plants – Gives turgor pressure • May not be present in animals CYTOSKELETON • Structural support & transport MICROFILAMENTS Actin – threadlike protein MICROTUBULES Tubulins – protein basis of cilia & flagella CENTRIOLES • Help in the process of cell division • Only in Animals PLANTS V. ANIMALS • CELL WALLS • LARGE VACUOLE • CHLOROPLASTS • CENTRIOLES • NO central VACUOLE • NO CHLOROPLASTS Awesome cell clip • http://www.youtube.com/watch?v=kxSLw1 LMvgk Cooperation Among Cells UNICELLULAR: Each individual cell is its own organism, but may form: - Colonies – Volvox, colonial algae - Biofilms – Bacteria on teeth, plaque • What are the advantages of cooperating? Disadvantages? MULTICELLULAR • Cells are specialized (specific roles) - eventually form tissues organs systems • What are our specialized cell types? Volvox http://www.youtube.com/watch?v=-V7LTyJuAy4&feature=related Colonies of Bacteria Cell to Cell Connections • Cells in same tissue communicate with each other through junctions – Tight junction : membranes are fused, stitched together; no passage – Desmosomes: protein fibers that anchor in cytoplasm of neighboring cells • – allow passage of materials – Gap junction : Channels formed by donut-shaped proteins btwn cells ; yes passage – Pits & Plasmodesmata : (plants) cell walls perforated with pits, strands of cytoplasm (plasmodesmata) run through pits connecting cells Can you find the connection? Extracellular Matrix • Solution of macromolecules (proteins & carbs) that surround cells in a tissue – Secreted by the cell itself to the space outside • Holds cells together • Allows them to migrate & interact • May regulate behavior in cells • Ex: collagen Question • You are not feeling well so you go to the doctor. She swabs your throat and grows the bacteria in the lab to identify. • She discovers that it is Streptococcus pneumoniae, a common but harmful bacteria. • When she looks in her microscope, does she see a nucleus in this organism? Why or why not? Question • You got a bad rash at sports camp. The doctor has prescribed you a cream that she says will help break down the cell wall of the organism that is growing on your skin. • Do you have a bacterial infection or a fungal infection? Or do you need more information? • Will this cream injure your skin cells in the same way? Why or why not? Question • Trace the path of protein production from DNA to export.