Chapter 5 Notes
Chapter 5 Notes Bio 301
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This 6 page Class Notes was uploaded by Kara Nichols on Thursday June 23, 2016. The Class Notes belongs to Bio 301 at Calhoun Community College taught by Felecia Ewing in Summer 2016. Since its upload, it has received 15 views. For similar materials see Principles of Biology 1 in Biology at Calhoun Community College.
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Date Created: 06/23/16
Chapter 5 Notes Thursday, June 239:12 AM Exchange of materials across membranes ○ Exocytosis ○ Endocytosis ○ Diffusion ○ Osmosis ○ Facilitated transport ○ Active transport • Fluid Mosaic Model (Essay question) ○ Made up of many different pieces and parts Phospholipids Glycoproteins □ Act as signals Cholesterol □ Most common steroid □ Insoluble in water □ Helps keep shape Transport proteins / integral proteins Peripheral proteins Glyco-lipids ○ Membranes are the consistency of olive oil Cholesterol helps stabilize/stiffen the membrane □ Scientists spliced a human cell and a mouse cell together □ They noticed that the proteins dispersed among the outside, they did not stay put • Exocytosis ○ "out" "exit" of the cell ○ Large molecules proteins ○ Vesicles containing large molecules fuse with the cell membrane and ONLY the contents are released Vesicles made by the Golgi apparatus Volume of the membrane increases ○ Example: Gland Cells Insulin Antibodies Neurotransmitters • Endocytosis Antibodies Neurotransmitters • Endocytosis ○ "in" "enter" the cell ○ The cell absorbs materials from the outside The membrane engulfs the particles ○ Pinocytosis "Cell-drinking" Things that are in a solution Liquid solutions of molecules move into vesicles that are formed to trap the molecules □ Salt water □ Sugar water ○ Phagocytosis "Cell eating" Cell ingests large objects □ Cells which have undergone apoptosis Programed cell death □ Bacteria □ Viruses Object is sealed in a large vacuole □ Phagosome Solid objects Creating large vacuole □ Phagosome ○ Receptor mediated endocytosis Specific molecules are let in by receptors □ Insulin receptors ○ Results in the formation of an intracellular vesicle by invagination of the membrane ○ Packages are unwrapped by the Golgi Lysosomes (made by the Golgi) are the ones that break down the parts ○ Volume of the membrane decreases • Diffusion ○ Due to the constant random motion of matter, in which molecules move from an area of higher concentration to an area of lower concentration ○ Molecules follow a concentration gradient (difference) naturally due to their motion ○ Everything is trying to reach equilibrium ○ Gases and fat soluble molecules often cross cell membranes in this manner ○ manner ○ Rate of diffusion Temperature □ Hot = fast □ Cold = slow Molecular weight □ Bigger = slower □ Smaller = faster Concentration gradient □ Higher the concentration gradient = faster Big difference □ Lower the concentration gradient = slower Small difference ○ Dialysis Diffusion of a solute through a selectively (semi)permeable membrane Blood dialysis gets rid of impurities ○ Osmosis The diffusion of water through a selectively permeable membrane Cell membranes are selectively permeable (semipermeable) The protein pores of cell membranes allow water molecules to pass through, but prevent the passage of larger molecules □ Aquaporin From high concentration to low concentration □ Hypertonic Solution have more dissolved molecules/particles than another solution If you place a cell in a hypertonic solution, occurs ◊ The cell shrinks ◊ Plasmolysis Plant cells The cell membrane shrinks away from the cell wall ◊ Crenation Animal cells The cell shrinks □ Hypotonic Solutions have fewer dissolved molecules than another solution If you place a cell in a hypotonic solution, the cell will expand because it will gain water Lysis - when a cell explodes Turgor pressure ◊ Plants, algae, and bacteria ◊ Plants, algae, and bacteria This is what helps plants stand upright ◊ Because they are protected by a cell wall, so they don't explode (lysis) □ Isotonic Solutions have the same number of dissolved molecules ◊ Water exchanges at an even rate ◊ Net movement • Facilitated Transport ○ Sugars, amino acids, and ions move through membranes by facilitated transport (diffusion) These types of molecules are too big to fit through pores like water ○ Carrier proteins Assist passage of these molecules through cell membranes □ Occurs from areas of high concentration to areas of low concentration • Active Transport ○ Sugars, amino acids, and ions Also includes carrier proteins ○ Active transport moves molecules from areas of low concentration to areas of higher concentration Requires ATP Molecules are forced to go against their natural tendency ○ It is the only "concentrating" process that allows us to put molecules where we want them to be ○ Example: Sodium (Na+)/ Potassium (K+) pump □ 3 sodium out □ 2 potassium in □ The outside is always positive □ The inside of the cell is negative ○ Consumes most of the ATP used in the body Energy • Energy ○ The capacity to do work ○ Potential energy Stored Not being used Kinetic energy ○ Kinetic energy Energy in motion ○ Laws 1st law □ Energy cannot be created or destroyed □ It can only be changed 2nd law □ When energy is changed, there is a loss of usable energy i.e. heat • ATP ○ Adenosine triphosphate Adenine 3 phosphate Ribose ○ Fuel of life Energy currency for reactions in cells High energy □ Last phosphate group ○ ADP + P can regenerate ATP ATP --> ADP + P ADP + P --> ATP ○ Coupled reactions ATP breakdown is often coupled to cellular reactions that require the input of energy ○ Exergonic reactions Release energy A + B --> C + D + energy □ Glucose + Oxygen --> 6 carbon dioxide + 6 water + 36-38 molecules ATP □ Cellular respiration ○ Endergonic reactions Require energy A+B+energy --> C+D □ 6Carbon dioxide + 6 Water + Solar energy --> Glucose + 6 Oxygen □ Photosynthesis ○ Functions Chemical work □ Synthesis Transport work □ Ions Mechanical work □ muscles □ muscles • Enzymes ○ A type of protein that accelerates a chemical reaction Cells only need a small amount Enzymes do not get used up, they just keep working ○ Speed reaction The enzyme binds to substrates (reactants) in the reaction □ Substrate is then converted into the product ○ Enzymes are specific Each enzyme is built to do a particular job and to bind to a particular substrate Induced fit model (lock and key model) □ The active site precisely fits the contours of the substrate (lock and key) □ Catalyze only a few closely related reactions Lactase breaks down lactose Notes: • Vesicles contain small particles • Vacuoles contain larger particles • 1 glucose can make 36-38 molecules of ATP • Fat molecules can pass through cell membranes (phospholipids) because they are non-polar • Diffusion = movement of everything • Dialysis = movement of the solute • Charged ions do not move through non-polar parts of membranes
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