Cell Structures 80197 - BIOL 2220 - 001
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80197 - BIOL 2220 - 001
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This 6 page Class Notes was uploaded by Jeni Erickson on Thursday September 1, 2016. The Class Notes belongs to 80197 - BIOL 2220 - 001 at Clemson University taught by John R Cummings in Fall 2016. Since its upload, it has received 12 views.
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Date Created: 09/01/16
Cell Structure 1. Cell a. Cella (store room or chamber) i. The smallest cell is 2 microns ii. The largest cell is more than a meter (nerve cell) iii. 200 different types of cells with different structures and functions b. Basic living, structural and functional units of all organisms 2. Cell Theory a. Cell is structural and functional unit of life i. In order for something to labeled as living, it has to be made up of cells. b. Activity of organism is combined results of individual and aggregated cells i. Activity of individual is based on the activity of the cells. c. Activity of cells depends on subcellular composition i. Rich in mitochondrion= produces lots of energy ii. Called the Principle of Complementarity d. Cells responsible for continuity of life i. Cells are made up of chemicals 3. Parts of a Cell a. Plasma membrane Allows a cell to have on thing on one side and something on the other Can limit the activity of a cell and decides what goes in and out of the cell. i. Composition of Plasma Membrane 1. Phospholipid bilayer a. Protecting the hydrophobic parts b. Makes up about half of border of cell c. 7-10 nanometers wide to keep optimum. 2. Integral proteins a. Fibrous Proteins b. Transport proteins c. Found in the bilayer and stretch all the way through the bilayer. 3. Peripheral proteins a. Found on one side of the bilayer (usually on the inside) b. Fibrous proteins c. Mostly Mechanical proteins d. Some act as enzymes ii. Functions of Plasma Membrane 1. Separate cells from external environment 2. Facilitate contact with other cells or foreign substances 3. Provide receptor sites 4. Control flow into and out of cell 5. Plasma membrane is selectively permeable a. Some things can pass while others cant. b. Determining Factors i. Molecular size (size matters) 1. Small is easier, as they get bigger, it gets harder and harder. ii. Solubility 1. Fat soluble pass right through 2. Water soluble cant pass through iii. Ionic Charge 1. Something with opposite charge of that of the plasma membrane is more likely to be pulled right through. iv. Carrier Molecules 1. Integral proteins that attract and transport things across the membrane. a. Some aren’t specific and some are (only certain substrates can pass through using a certain protein. v. Membrane transport processes 1. Passive: no energy required a. Diffusion: passing of matter from high concentration to low concentration until equilibrium is reached. i. Molecular size and temp affect diffusion. b. Facilitated diffusion: involves a carrier protein. Using an integral protein that is either a channel protein or carrier protein. i. Carrier protein changes shape with moving solute into or out of the cell. ii. Channel protein: if it fits in the tunnel, then it will go through iii. Concentration gradient, different carrier protein pickup speeds (how fast they can operate), and the amount of proteins present affects facilitated diffusion, c. Osmosis (water can not be concentrated) i. Movement of water across a selectively permeable membrane ii. Is regulated by solute concentration in the water and osmotic pressure- higher pressure on one side will move to the lower pressure side to equalize it. iii. Water is looking to equalize the solute concentration on both sides. Tonicity (part of osmosis) c. Isotonic- both side’s concentration is equal d. Hypertonic: more concentrated outside cell i. Hypertonic solutions suck water (water moves into cell when call is hypertonic. e. Hypotonic: less concentrated outside cell. f. Osmolality: molarity of a solution times the number of ions you would get from ionization. i. Population estimate (number of particles) ii. Saline solution is 1 molar saline solution. Molarity=1. It is a 2-osmol solution. g. Filtration: dependent on a pressure gradient. Goes from high to low pressure. iii. Active 1. Active Transport: requires energy; moves against the concentration gradient. Uses ATP. a. 40% of ATP produced by a cell is used for active transport b. Carrier molecules are specific to certain molecules i. Example: Sodium-potassium pump 1. Does this against concentration gradient. 2. Exocytosis a. A steroid molecule is produced in cell and then released into body. b. Vesicle is formed around particles i. Vesicular transport ii. The vesicle is made up of phospholipids 3. Endocytosis Moving large things into the cell by making a vesicle around the cell and moving it in. a. Phagocytosis i. Cell takes in solid particles. ii. Example: immune cells b. Pinocytosis i. Moving liquid molecules into cell. c. Receptor-mediated endocytosis i. Membrane has receptors on the exterior surface ii. When the particle binds to the cell, the receptors are activated and a vesicle is formed to bring it into the cell. iii. Receptor is called clathrin 1. Clathrin a. Protein coating on cytoplasmic face of vesicle b. Clathrin coated vesicle iv. Plasma Membrane Specializations 1. Microvilli: allows for more interaction between the cell and the things on the external side of the cell. 2. Tight junctions: Adjacent cell fused integral proteins. Makes a tight junction that is impermeable. 3. Desmosomes (anchoring junction): two cells with protein filaments interact together. Not tight, but they interact with each other. Provides some resistance to cellular tension so cells don’t tear as easily. 4. Gap Junctions: (communicating junction) makes one long tunnel that moves things from one cell to another using a connectson. a. Channel proteins connect and fuse together to make a tunnel from one cell to the next. Muscle contractions use this. v. Membrane Potentials 1. Differences in electrical charges across a membrane 2. Results from distribution of ions on both sides of membrane a. Predominantly potassium, sodium and chloride b. Resting Membrane Potential i. Sodium potassium pump 1. Potassium has more inside cell than outside 2. Sodium has more outside of cell than inside 3. More sodium outside than we have potassium inside. 4. Inside of cell is negative compared (-70 millivolts) to outside of cell and therefore polarized b. Organelles Organella (instrument or tool) Specialized portions of a cell that have a characteristic structure (morphology) and assume a specific role in cell growth, repair, maintenance or control. 1. Assume a specific function/role inside the cell. ii. Nucleus 1. Nuclear components a. Genetic material b. Nuclear envelope i. Contains a bunch of nuclear pores c. Nucleoplasm d. Nucleoli: small spherical bodies e. Nucleolus i. Ribosomes are assembled here and transported out. iii. Mitochondria: 1. Function: produces ATP. 2. Can replicate independently 3. Possess their own DNA a. This entire DNA comes from mom. (Exactly from mom) 4. Has a phospholipid bilayer around it.
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