8/26 Introduction to Cells Biology ? Study of Living Things What is life? Characteristics of life for most living things: Require energy ? must eat Plants get energy from sun Grow Reproduce Respond to stimuli Cells are the smallest units of life and possess all the above characteristics Cell Theory: Cells are the smallest units of life Cells come from preexisting cells Note: Mutations in the genetic material affect whether the cell functions normally. Other Characteristics of Cells: Contain water Contain at least 10,000 different types of molecules Cells have different shapes and sizes About 200 different kinds of cells in humans Trillions of cells in humans Many different kinds of cells - examples: Red blood cells Leaf cells Sperm cells Plant root hair cells Motor neurone cells Pollen cells Organisms are constantly losing cells and making new ones Cell Organelles Structures inside cells that carry on specific tasks They coordinate basic life functions. Protoplasm: Cytoplasm Nucleoplasm Plasma (Cell) MembraneOuter boundary Pores allow easy movement of small molecules Nucleus: Controls activity of cell (?brain?) Contains two other organelles Chromosomes ? genetic material Nucleolus ? Small spherical structure Produces ribosomes Chromosomes ? two forms: Chromosomes : Compact rod-shaped ? during cell division Chromatin: Long stretched-out form ? during ?normal? phase Mitochondria: Energy production ? the ?Power House? of the cell Exercising produces more mitochondria Endoplasmic Reticulum (ER) Membranous structure Connects to nucleus Spreads throughout cytoplasm Rough ER makes and folds proteins Smooth ER makes lipids Ribosomes On rough ER Site of Protein Synthesis (making proteins) Golgi Body Sugars are made Some macromolecules are assembled ? example: components of milk The Making of a product: Milk What is milk? A protein/sugar molecule plus a fat droplet suspended in water. (Plus other things we are not going to consider such as vitamins, immune factors, etc.) DNA sends a message out to the cytoplasm Message tells the ribosomes on the rough ER to make a protein for milk (structural protein) The manufactured proteins are folded and sent to the Golgi Body Meanwhile, lipid molecules are produced in the smooth ER. Meanwhile sugar molecules are produced in the Golgi In the Golgi the protein and sugar are assembled forming a milk protein. Secretion: Lysosomes: Small round vesicles Capture and take apart bacteria, worn-out organelles, and debris Contain enzymes ? to digest debris Large white blood cells called macrophages (which fight infection) contain many lysosomes Peroxisomes Store digestive enzymes Digest fatty acids Rid the cell of toxic peroxides A missing enzyme will cause some type of disorder Summary ?review of the big biology picture: (Quarks) ----- subatomic particles ----- atoms ----- molecules ----- macromolecules (including biological macromolecules) ----- organelles ----- cells (alive) ----- tissues (nerve, muscle, blood, etc.) ----- organs (heart, brain, liver, etc.) ----- organs ----- organ systems (digestive, circulatory, reproductive, etc.) ----- organisms (species) ----- populations (of single species) ----- communities (contain more than one species) ----- biomes (major communities - dessert, rainforest, etc.) ----- biosphere
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