BSC 108 Week 4 notes
BSC 108 Week 4 notes BIO 108
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This 6 page Class Notes was uploaded by Matt Cutler on Monday September 19, 2016. The Class Notes belongs to BIO 108 at University of Alabama - Tuscaloosa taught by Dr. Yates in Fall 2016. Since its upload, it has received 3 views. For similar materials see Intro to Biology for Non-Majors in biology, science at University of Alabama - Tuscaloosa.
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Date Created: 09/19/16
Chapter 5- The Working Cell Wednesday, September 14, 2016 10:27 AM 1. Basic concepts a. Chemical energy i. A form of potential energy b. Energy can be changed from one form to another i. It CANNOT be created or destroyed ii. This is the conservation of energy principle and the 1st Law of Thermodynamics. c. Heat i. Is a type of kinetic energy that is a product of all energy conversions d. Entropy i. A measure of disorder, or randomness ii. All energy conversions increase the entropy of the universe e. Food Calories i. A calorie is the amount of energy that raises the temperatureof one gram of water by one degree Celsius. ii. calories are very small units of energy 1) Not practical for measuring the energy in food iii. A food calorie (Capitol C) is actually a kilocalorie 1) 1,000 calories. iv. Calories in Food □ Foods with the most C-H bonds Store the most potential energy Have the most calories Make the most ATP f. Cellular respiration i. The energy-releasingchemical breakdown of fuel molecules ii. Provides energy for the cell to do work. ATP= Adenosine Triphosphate iii. A series of energy transferringchemical reactions 1) The chemical bonds in foods are broken down. ADP= Adenosine Diphosphate 2) The energy in those bonds is shifted to the bonds in ATP ATP is the energy currency in all cells About 40% of the energy in foods is transferred to ATP The remainder becomes heat and is lost g. ATP i. Examples of how ATP transfers energy to become ADP 1) Motor proteinsperform mechanical work 2) Transport proteins 3) Chemical reactants h. The ATP Cycle i. Enzymes i. Metabolism is the sum total of all chemical reactions that occur in organisms ii. Few metabolic reactions occur without the assistance of enzymes iii. Lower the activation energy for chemical reactions iv. Each enzyme is very selective 1) It catalyzes specific reactions v. Each enzyme recognizes a specific substrate ATP= AdenosineTriphosphate ADP= Adenosine Diphosphate v. Each enzyme recognizes a specific substrate 1) The active site fits to the substrate, and the enzyme changes shape slightly 2) This interaction is called induced fit vi. Enzymes can function over and over again vii. Inhibitors 1) Can inhibit a metabolic reaction 2) Some bind to the active site, as substrate imposters 3) Bind at a remote site, changing the enzyme's shape j. Activation energy i. Energy that activates the reactants in a chemical reaction ii. Triggers a chemical reaction to proceed 2. Membrane stuff a. Passive Transport: Diffusion Across Membranes Molecules contain heat energy They vibrate and wander randomly i. Diffusion 1) One result of the movement of molecules 2) Molecules tend to spread into the available space a) Ex: bottle of perfume opened in a big room 3) Passive transport; no energy needed □ Equilibrium The same number of molecules on both sides of the plasma membrane ii. Facilitated diffusion 1) The transport of some substances by specific transport proteins that act as selective corridors b. Osmosis and Water balance in cells Osmosis is the spontaneousnet movement of solvent molecules through a semi permeable membrane in the direction that tends to equalize the solute concentrationsof the two sides. i. Water balance in animal cells □ The survival of a cell dependson its ability to balance water uptake and loss. □ Osmoregulation- the control of water balance in animals ii. In plant cells □ They have rigid cell walls □ They are at the mercy of their environment c. Solutions i. A hypertonic solution □ Has a higher concentrationof solute than equilibrium per volume water ii. A hypotonic solution □ Has a lower concentration of solute iii. Isotonic solution □ Equal concentration of solute d. Active Transport: The pumping of molecules across membranes Requires energy to move molecules across the membrane i. Exocytosis and Endocytosis: Traffic of large molecules 1) Exocytosis a) Secretes substances outside of the cell 2) Endocytosis a) Takes material into the cell b) Receptor-mediatedendocytosis i) Triggered by the binding of external molecules to membrane proteins i) Triggered by the binding of external molecules to membrane proteins e. The role of membranes in cell signaling i. Cellular communication 1) Begins with the reception of an extracellular signal ii. The signal transductionpathway 1) Consists of proteinsand other molecules that relay the signal