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THE CELL WHAT IS A CELL? Basic unit of life 100 trillion estimated in the human body! Composed of organelles: “tiny organs” that all have a particular job, function UNICELLULAR ORGANISMS Unicellular = single (one) cell In terms of numbers, they dominate! ORGANISMS Multicellular = many cells Depend on cooperation and communication between many specialized cells Specialization: Only in multicellular organisms Development of cells in different ways that enable them to carry out different tasks ORGANIZING A MULTICELLULAR BEING Organism Organ System Organ Tissue Cells ORGANIZA Tissues: TION group of similar cells that perform a particular function Organs: group of tissues that perform a particular function Organ system: group of organs that work together to perform a particular function OF CELLS Hooke, Viewed cork; coined the term “cells” van 1665 Leeuwenhoek, 1673 First to view cells under with a microscope he created! Schleiden, Botanist, plants made of cells Schwann, 1839 Zoologist, animals made of cells Virchow, 1838 1855 Researched cancer cells and proposed that new cells only come from division of other cells CELL THEORY All living things are composed of cells Cells are the basic units of structure and function in living things New cells are produced from existing cells CATEGORIES Prokaryotes No membrane bound organelles Genetic material not in the nucleus Cell membrane Small* Eukaryotes (you!) Have organelles Genetic material contained in nucleus Cell membrane Large* EUKARYOTES VS. PROKARYOTES Prokaryote Examples: Bacteria Archaebacteria Eukaryote Examples: Animal cells That’s your cells, pal! Plant cells Trees, grass, ferns, leaves PLANT VS. ANIMAL CELLS Cell Wall Central Vacuole What the heck is the difference? Chloroplast EUKARYOTIC CELL MEMBRANE Boundary of the cell Made of a phospholipid bilayer C ELL MEMBRANE Function separates cell from outside environment controls what enters or leaves cell O2, CO2, food, H2O, nutrients, waste phosphate “head” recognizes signals from other cells Polar allows communication between cells lipid “tail” Non-polar Structure of the Double layer of fat phospholipid bilayer Protein molecules (50%) Cell Membrane Receptor proteins Structural proteins Protein channels Carb chains ID cards CELL WALL Found in plant and bacterial cells Rigid, protective and supportive barrier Located outside of the cell membrane Porous Made from fibers of carbohydrates and proteins Plant Cell Walls are made from Cellulose