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Transcript
NOTES: 7.2 (Cell Structures & Functions) Comparing the cell to a factory: ● each cell part (“organelle”) can be compared to a specialized machine in a factory; ● each part towards the functioning of the cell as a whole… Cell Organization: ● each eukaryotic cell can be divided into 2 major parts: 1) ; 2) CYTOPLASM: ● CYTOPLASM: the portion of the cell outside the nucleus; organelles suspended in cytoplasm ; all other NUCLEUS: ● NUCLEUS: (the coded instructions for making all of the cell’s proteins); ● considered the ; ● nucleus is surrounded by a nuclear envelope NUCLEAR ENVELOPE ● double membrane which encloses the nucleus; ● includes many nuclear pores (holes) which CHROMATIN ● threadlike complex of DNA bound to proteins which in eukaryotic cells CHROMOSOMES ● ; ●human cells have NUCLEOLUS ● spherical region in the nucleus - Organelles that Store, Clean Up, and Support: ● vacuoles & vesicles ● lysosomes ● cytoskeleton VACUOLE: ● (of water, salts, proteins, carbs); ● in animal cells, vacuoles are smaller than in plant cells PLANT VACUOLES… ● may contain soluble pigments in some cells (red and blue pigments in flowers); ● help protect from predators by storing waste products that may also be poisonous compounds ● contractile vacuole: specialized vacuole that pumps excess water out of cell. VESICLES: ● VESICLES: small, membrane-enclosed structures that , or to and from cell surface LYSOSOMES: ● the cell’s “clean-up crew”! ● that break down macromolecules into smaller subunits; ● ; ● can destroy cells by breaking open all at once and digesting the cell from within CYTOSKELETON: ● CYTOSKELETON: ; also involved in transport of materials within the cell, as well as whole-cell movement ● includes protein filaments: -microfilaments -microtubules MICROTUBULES & MICROFILAMENTS ● ● structural support to cell; maintain shape ● Microfilaments: ● threadlike structures; ● made up of protein: ● ● microfilament assembly & disassembly allow amoebas & other cells to “crawl” along surfaces Microtubules: ● thin, hollow cylinders made of protein: ● ; ● can serve as “tracks” to guide organelle movement; ● involved in in cell division; make up SPINDLE FIBERS / CENTRIOLES (in animal cells) ● responsible for movement of flagella & cilia FLAGELLA and CILIA: ● FLAGELLA: longer usually single extensions; ● CILIA: ; wavelike motion used to sweep extracellular material over/away from cell Organelles that Build, Modify, and Transport Proteins: ● ribosomes ● endoplasmic reticulum ● Golgi Apparatus RIBOSOMES: ● -small particles of RNA & protein -follow coded instructions from DNA -made in the nucleolus -cells especially active in protein synthesis often contain large #s of ribosomes -may be free (in cytoplasm) or attached to the ER ENDOPLASMIC RETICULUM (ER): ● extensive network of internal membranes ● used to ● can be (ribosomes) or (no ribosomes) Rough ER: ● rough appearance due to ribosomes on outer surface; ● newly made proteins leave the ribosomes and are ● ; ; Smooth ER: ● synthesizes lipids, phospholipids, steroids ● detoxifies drugs and poisons GOLGI APPARATUS: ● stacked, flattened membranes ● finishes, sorts, packages and ships many cell products (a.k.a. ) Organelles that Capture and Releas Energy: ● chloroplasts ● mitochondria CHLOROPLASTS: (a.k.a. “the organelles that feed the world”) ● ; ● (convert light energy into “food”, or chemical energy) MITOCHONDRIA: ● ● convert the into usable energy packets for the cell ● the # in cells varies and is related to the cell’s metabolic activity (i.e. if a cell uses more energy, it will have more mitochondria!) Cellular Boundaries: ● cell wall ● cell membrane ● CELL WALL: - semi-rigid structure outside of cell membrane of ; (CELL WALL, cont.) - in plants, consists of CELLULOSE fibers; - provides support, limits cell’s volume, and protects against fungi and/or microorganism infection. - most cell walls are porous enough to allow water, oxygen, carbon dioxide, etc. to pass through CELL MEMBRANE: What must a membrane do? ● let some things leave / enter cell ● ● be flexible as cell changes shape ● cell membranes form a LIPID BILAYER that is & ; ● The cell membrane is composed of molecules called . -one end is strongly nonpolar ( ); -one end is extremely polar ( ) ● the nonpolar lipid “tails” are repelled by polar water molecules; the polar “heads” of the molecules form hydrogen bonds with water molecules. ● So, every phospholipid molecule orients so that its polar “head” faces water and its nonpolar “tails” face away... two layers are formed with the tails facing each other...the result is called a . ● Lipid bilayer membranes are: ● PERMEABLE to: -nonpolar molecules: -small polar molecules: ● IMPERMEABLE to: -ions ( ) -large polar molecules: 3 Main Types of Membrane PROTEINS… 1. 2. 3. 1. Channels: ● a channel will transport only certain kinds of molecules...which gives the cell membrane its nature 2. Receptor proteins: ● from the cell’s environment 3. Cell surface markers: ● identify your body‘s cells as belonging to you ( )