Life 102, Week 1 Notes
Life 102, Week 1 Notes Life 102
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This 3 page Class Notes was uploaded by Kyra Ferguson on Thursday January 21, 2016. The Class Notes belongs to Life 102 at Colorado State University taught by Erik Arthun in Winter 2016. Since its upload, it has received 17 views. For similar materials see Attributes of Living Systems in Life Science at Colorado State University.
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Date Created: 01/21/16
Chapter 1 What is Biology? Biology derived from roots meaning "life" and "the study of" The scientific study of life. Life is everywhere on Earth. Biology studies life in all of its forms and at all levels of organization and time. Biology is broad, multidisciplinary utilizing chemistry, physics, biology, etc. Life as at the same time very uniform and very diverse. Uniformity is exhibited at cellular/molecular level, all organizations consist of cells. Diversity can be used to classify groups "taxonomy". Chapter 2: Chemical Context of Life How do we use Chemistry in Biology? Element substance that cannot be broken down into other substances by chemical reaction ie., Gold Compound two or more different elements combined in a fixed ratio ie., Sodium Chloride, aka salt There are 25 chemical elements essential for life. 96% of life is comprised of Oxygen, Carbon, Hydrogen, and Nitrogen. The other 4% is comprised of Calcium, Phosphorous, Potassium, Sulfur, Sodium, Chlorine, Magnesium, and trace amounts of another 14 elements. Atom smallest unit of an element, composed of protons, neutrons, and electrons. An atom is mostly empty space. Dalton the weight of a proton or neutron. An electron is considered so light that it weighs practically nothing. Name Weight Charge (Daltons) Proton 1 +1 Neutron 1 0 Electron 0 1 The nucleus of an atom, comprised of protons and neutrons, is so small it is equivalent to an eraser at the center of a football stadium, with the stadium being the rest of the atom. Elements can be written with numbers as a notation to their weight and element number Atomic number of a nucleus is the number of protons in an atom's nucleus. The number of protons there are determines what element it is. Neutron and electron numbers can vary from element to element, but protons cannot change unless it were to become a different element, for example: He 2 Atomic mass is the weight of protons and neutrons, for example: He 4 Atoms can undergo changes: 1) Add or lose an electron Ionatom with unpaired proton or electron. An atom that loses an electron becomes positively charged, and an atom that gains an electron becomes negatively charged. 2) Isotopes atoms with different number of neutrons The bottom number is the number of protons (the atomic number) which does not change even as an isotope. Some isotopes are radioactive. Electrons are arranged in shells. Shells are found at different distances to the nucleus. Shells have a maximum number of electrons that can be in it. Shell 1: 2 Shell 2: 8 Shell 3: 10 The outermost shell of an element is called the valence shell. Atoms want full valance shells, so they bond. How atoms get full valence shells: Strategy 1: Donate or accept electrons This makes an ionic bond (name from two ions bonding) Cation (positive charged atom) and anion (negative charged atom) attract Ions can dissolve in water to separate Compounds/molecules have characteristics different from the atoms they are composed of. Strategy 2: Two atoms share their electrons to make a covalent bond H H They share the electrons, but both get to count both electrons as a full valance shell Polar covalent bond electrons not equally shared in a covalent bond due to electronegativity (strength in tugowar over electrons) Polar compounds interact with polar compounds. They attract eachother to make a weak bond called hydrogen bond. A hydrogen bond is very important in things like DNA. Chemical Reactions Molecules react with each other Reactants Products , for example: Na+Cl NaCl Mass conservation law all atoms present in reactants are still present in the products Every chemical reaction is reversible in theory Chemical equilibrium the rate of forward reaction equals the rate of reverse reaction
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