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Transcript
Microscopes • simple light scope- used 1 lens and natural light • compound light scope- series of lenses to magnify objects in steps (this is what we use in class) Magnification- the ability to make objects appear larger Resolution- the ability to distinguish between two objects that are close together Microscopes electron scope- uses a beam of electrons instead of natural light to magnify objects - 3 types 1. scanning electron scope (SEM)- used to scan the surface of cells to determine their 3D shape 2. transmission electron scope (TEM)- used to study the structures within a cell 3. scanning tunneling scope (STM)- uses electrons to see the atoms attached to the surface of a molecule Cells- the basic unit of living organisms van Leeuwenhoek was the first to see cells through a microscope. Robert Hooke saw dead cork cells. (1665) Schleiden concluded that all plants are composed of cells. (1838) Schwann concluded that all animals are composed of cells. (1839) Virchow concluded that cells come from other cells. (1855) The Cell Theory 1. All organisms are composed of 1 or more cells.(single celled or multicellular organisms) 2. The cell is the basic unit of organization of organisms. 3. All cells come from cells. Cell Types prokaryotes- cells that lack membrane bound organelles (internal cell structures) (mainly a nucleus) - usually unicellular Example: bacteria Cell Types eukaryotes- cells with membrane bound organelles - mostly multicellular organisms Example: plants & animals EXCEPTION: yeast & algae are unicellular eukaryotes - composed of a phospholipid bilayer - 2 layers of lipids tail to tail - lipids have a polar phosphate head (water loving) attached to 2 non-polar fatty acid tails (water hating) The boundary between the cell and its environment - maintains homeostasis - regulates what goes in and out of the cell *selectively permeable- it allows some molecules to pass through while it keeps other molecules out proteins are embedded in the membrane - recognition proteins identify the cell (AKA: cell surface markers) - transport proteins allow wastes and substances to pass through the membrane (AKA: carrier proteins) - receptor proteins monitor the outside environment and send information to the nucleus cholesterol is embedded in the membrane - prevents fatty acid tails from sticking together - provides strength and rigidity to the membrane The Fluid Mosaic Model- the current model of the plasma membrane. Flexible and fluid like in movement & patterns of proteins look like a mosaic Nucleus- THE BOSS- contains the directions to control cell activity Nucleolus- organelle inside the nucleus that makes ribosomes Chromatin- loosely coiled strands of DNA found within the nucleus Nuclear Envelope- structure that separates the nucleus from the cytoplasm. It is a double membrane made of two phospholipid bilayers containing small nuclear pores for substances to pass through. Nuclear Matrix- protein skeleton helps maintain shape Cytosol- the clear, gelatinous fluid inside the cell (cytoplasm) Ribosomes- PROTEIN FACTORY- organelle in charge of protein synthesis (not membrane bound) 2 types: free floating, attached Rough Endoplasmic Reticulum (ER)- ASSEMBLY LINE- series of highly folded membranes that is the site of cellular chemical reactions, ribosomes attach to the outside to make the ER rough Smooth ER- ASSEMBLY LINE- lacks ribosomes, highly folded membranes involved in the production and storage of lipids Golgi Apparatus- POST OFFICEflattened system of tubular membranes that modifies proteins to be sent to various places Vesicles- associated with the golgi apparatus, membrane bound structures that carry proteins Vacuoles- PANTRY- membrane bound space used for storing materials (food, enzymes, etc.) large in plant cells, small in animal cells Lysosomes- HOMICIDE SAC- membrane bound organelle that contains digestive enzymes, they digest worn out organelles, viruses, bacteria, etc. • Peroxisome – Contains oxidative enzymes to perform oxidation reactions – Each cell has different types of peroxisomes Mitochondria- POWER HOUSE- transforms energy for the cell has an outer membrane and a highly folded inner membrane (cristae membrane); the mitochondria has its own DNA *Cilia- short, numerous hairlike projections that help with movement *Flagella- long whiplike projections used for locomotion Ex: sperm Cytoskeleton- support structure within the cytoplasm that helps keep cell shape and assist organelles with movement - Microtubules- thin, hollow cylinders of protein - Microfilaments- thin, solid protein fibers PLANT ORGANELLES Plastids- organelles used for storage of pigments, starches, lipids, etc. - Chloroplast- organelle that captures light energy and produces food for later use they contain chlorophyll, a green pigment that traps light energy Cell Wall- rigid structure located outside the plasma membrane that provides additional support and protection, it will let anything pass through itpresent in plant cells, most bacteria, and fungi ANIMAL CELL ORGANELLES – only found in animal cells Centrioles - Aid in mitosis, cellular reproduction; found outside of the nucleus