LIFE 102 Chapter 7 and 8 Notes
LIFE 102 Chapter 7 and 8 Notes Life 102
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This 7 page Bundle was uploaded by Whitney Kendall on Monday October 3, 2016. The Bundle belongs to Life 102 at Colorado State University taught by Jennifer L Neuwald in Fall 2016. Since its upload, it has received 3 views. For similar materials see Attributes of Living Systems in Life Science at Colorado State University.
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Date Created: 10/03/16
Chapter 7: Membrane and structure Membranes: Boundary layers of cells, and organelle inside cells Function: keep things where you want them to be- separated Selective Permeability: some things can pass, others cannot For membranes Phospholipid Bilayer: Hydrophilic head, hydrophobic tail Tails merge together keeping water out of their area, the heads are by the water Hydrophobic regions of proteins can sit inside the bilayers, same with hydrophilic ones but on the outside Fluid Mosaic Model- different parts of a membrane moving around Lots of lateral movement, they flip very rarely Fluid: membrane components are not stationary Mosaic: phospholipids, proteins and other macromolecules Ex: mouse cell + human cell= a hybrid cell; in an hour the proteins from each cell combined to be equally dispersed in one cell Membranes are fluid because… 1. Temperature a. Warm Temp= fluid b. Cool temp= viscous 2. Fatty Acid Tails a. Fluid- unsaturated tails prevent packing because of double bonds b. Viscous- saturated tails pack together c. Example: winter wheat; starts to produce unsaturated phospholipids when the temperature starts getting colder allowing it to still move thus allowing it to reproduce and still grow in the winter 3. Cholesterol a. Amphipathic b. When it's hot it makes less fluid because it's there, when it's cold it makes it more fluid because it maintains spacing c. Maintains equilibrium Membrane Structure and Function Protein determines membrane Function Membrane Proteins 1. Integral ( most transmembrane) 2. Peripheral- on the edge of the cell membrane 3. Selective Permeability Transport proteins: regulate and facilitate movements of things into and out of the cell O Ions, Sugars, and amino acids go in 2 CO 2ons, and waste go out Move through the cell membrane 1. Phospholipid Bilayer: nonpolar molecules a. Must travel through a small hydrophobic area 2. Transport proteins: polar molecules a. Large nonpolar molecules can go through here too Transport Movement based on concentration gradient Number of solutes in a solution Passive transport: molecules are moving through diffusion from high area to low are; doesn’t require energy Active transport: move solute up the concentration gradient; requires energy o Ex: ball rolls down the hill vs rolling it back up [c]- Concentration Osmosis Water goes to where the concentration is higher Isotonic solution: equal [c] inside and outside the cell Water is coming and going in equal trades Hypotonic solution: [c] inside much higher than outside the cell Need osmosis to equilibrate the concentration Need to make fluid inside increase- water goes into the cell, then the cell expands Hypertonic solution: [c] inside much less than outside the cell Water is going to move out to equilibrate- the cell is going to shrink Plasmolysis Hypertonic- Plasmolyzed Facilitated Diffusion- diffuses down, but needs some help 1. Channel Proteins: solutes from the extracellular fluid pass through channel proteins into the cell's cytoplasm 2. Carrier Proteins: Teeter or pump to open so the solute can enter then teeters and opens into the cell; change shape a. Active transport b. Powered by ATP i. Example: Na+ wants to go outside, K+ wants to go inside- both against [c] gradient ii. Pump grabs Na+; phosphate group is added, it changes shape iii. Cell pays phosphate group with ATP iv. Pump folds and splits out Na+; new shape makes it no longer ideal for Na+ v. Pump grabs K+, drops P vi. Folds back; changes shape, now no longer ideal for K+ vii. Splits "in" K+ c. Unequal transport rates= membrane potential (voltage across membrane) i. 3 Na+ ions for every K+ ion ii. Ions same thing; cations (+), anions (-) go to opposite sides without energy; + to - and - to + Electrochemical Gradient 1. Concentration Gradient 2. Membrane Potential 3. Both dependent on each other for molecule transportation Proton Pump Plants, fungi and bacteria Pumping H+ out- against [c] gradient and membrane potential Invest a little ATP now, you can keep more later like cotransport proteins Cotransport Pumps in sucrose and diffuses H+ Sucrose-H+ cotransporter- need H+ with sucrose Vesicle-mediated Transport- for large things or large quantities Vesicles transported from ER to Golgi apparatus then from there to other places Exocytosis- exit the cell Endocytosis Phagocytosis: brings in food Pinocytosis: brings in liquids Receptor-mediated endocytosis: receptors outside waiting for enough of a molecule and then transports it once it gets enough/ full- more efficient to wait and get what you need Cell- Cell Recognition Glycoproteins- cellular ID's Helps cells to identify what cells are and if they're ok Glycolipids- Cellular ID's Tells cells what they are REVIEW Specificity: proteins transport specific molecules Diversity: many types of proteins to transport many types of molecules Passive Transport Proteins Channel Proteins Carrier Proteins Active Transport Proteins Carrier proteins- require ATP Chapter 8: Metabolism: all chemical reactions in a cell; change Catabolic: releasing energy, moving down the gradient and the cell gains energy Anabolic: moving up the gradient, energy is consumed and the cell looses energy Energy: capacity to do work Kinetic Energy: energy associated with moving atoms/ molecules Heat: movement of molecules Light Potential Energy: energy associated with the location or structure of an object Chemical energy: energy stored in the bonds of molecules o Transformed when bonds are broken Thermodynamic Laws 1. The energy of the Universe is Constant- energy is neither created nor destroyed 2. Entropy (disorder) of the universe is always Increasing a. A ball that’s parts are blown away is increasing in entropy because its expanding b. While running, you give off heat because it was excess energy c. Large molecule has structured bonds with many molecules; when it goes through a reaction it is now less structured and in many pieces and results as being high entropy d. If entropy increases the reaction is spontaneous e. If entropy decreases the reaction is non-spontaneous and requires energy and work "Gibbs Free Energy" or Free Energy: measure of how much of the total energy in the system can be used to do work Usable energy in chemical bonds Before vs. Usable energy in chemical bonds after= ΔG ΔG= G - G productreactants ΔG< 0 = Spontaneous Exergonic ΔG > 0 = Non Spontaneous Endergonic Endergonic reactions are fueled by exergonic reactions Cellular work- need energy to do work 1. Chemical work: creating other molecules 2. Transport Work: transport proteins in membranes 3. Mechanical Work: proteins that move on the cytoskeleton ATP: Adenosine Triphosphate Hydrolysis of ATP o Breaks off terminal phosphate Becomes: Inorganic phosphate + ADP + Energy ΔG= -7.3 kcal/mol Exergonic How does ATP work? o Glutamic Acid + Ammonia = Glutamine ΔG= 3.4 kcal/mol o o 3.4+ (-7.3)=-3.9 kcal/mol its overall spontaneous Where does it come from? o Light energy from the sun is converted to chemical energy (ATP), then broken down into ADP and inorganic Phosphate and then converted into ATP o 10,000,000 molecules/ cell/ sec How fast reactions occur? o Some are fast, some are slow o Activation energy: energy of reactants increases to get to transition state Heat can help this Ex: fire Enzymes: proteins speed up (catalyzes) but are not consumed by reactions Lowers activation energy required Interacts with the substrate (reactant) Induced fit: Substrate fits into the enzyme and it changes shape to fit around it Either hydrogen or ionic (weak bonds); keep substrates there Substrates react to form products, the enzyme then releases Active site can… 1. Act as a template 2. Stress substrate bonds (in lowering activation energy) 3. Provide microenvironment necessary at transition a. Based on tertiary structure of protein- hydrophobic or hydrophilic 4. Bond to substrate briefly Enzymes DO NOT add energy to a reaction Change the ΔG Get changed in the net reaction Substrate concentration affects rate of enzyme activity Enzyme concentration affects rate of Enzymatic Activity Positive correlation Temperature affects rate of Enzymatic activity Can affect how well enzymes function, wont when too hot or too cold; dependent on organism pH affects rate if Enzymatic Activity Lower pH is more acidic; deviating from optimal pH prevents functioning efficiently Regulation of Enzymatic Activity by: Cofactors: additional substances required for catalysis o Enzymes sometimes need them in order to fit in the active site; wont factor without them Coenzyme: an organic cofactor Enzyme Inhibitors: molecules that hinder activity o Competitive: they bind to the active site, blocking the substrate from bonding there Penicillin o Non-competitive: will bind to a different part on the enzyme, changing the shape and function but not blocking the active site o Reversible or non-reversible Allosteric Regulation: enzyme's structure (and function) is affected by binding of molecules; changes shape o Activators Stabilizes enzyme to work ii. Inhibitors Stabilizes enzyme to an inactive form- can't function iii. Cooperatively Blocks one active site, but allows the rest to be active 2. If enzymes are regulated so is metabolism Feedback Inhibition Start with substrate, turns into multiple intermediate products which become reactants then finally will be the product. Product then binds to allosteric site and shuts down the enzyme until product concentration is low again. More product= less the enzyme will function Regulation keeps concentrations just right Regulate Enzymes -> Regulate Metabolism 1. Environment a. [c] substrates b. [c] enzymes c. Temperature d. pH 2. Molecules a. Cofactors (coenzymes) b. Inhibitors (competitive or noncompetitive) c. Allosteric inhibitors or activators
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