TEST 1 January 14 2014 SI sessions Monday Tues Thursday BLOC 105 6PM Chapter 1 pages 1 5 12 25 skim the rest Chapter 2 pages 31 43 Scientific Inquiry Scienceo study of the natural world o To know nature Types of biological inquiry o Discovery of science inductive reasoning Starts with specific observations and comes to a general explanation for observations o Hypothesis based science deductive reasoning Fig 1 24 Making Hypothesis Hypothesis a tentative answer to a well framed question o Testable o Falsifiable o Verifiable Scientific Theory broad scope supported by accumulated evidence from many hypotheses leads to new hypotheses can be modified or rejected Examples of scientific theories o Supported Cell theory Atomic theory Evolutionary theory Chromosomal theory o Rejected 5 kingdom theory of biodiversity Fig 1 4 levels of biological organization Chemical Context of life the foundation o Element My definition single substance made up of a group of atoms A substance that cannot be broken down to other substances by chemical means 25 92 natural elements are essential for life o o o Molecule My definition Multiple atoms combined Two or more atoms held together by a chemical bond Compound My definition Substance made up of multiple elements and molecules that are chemically combined Two or more different elements held together by chemical bonds has different properties from elements alone Atom Smallest unit having physical and chemical properties of an element Subatomic particles Charge mass location Proton o 1 dalton amu nucleus Neutron o Neutral 1 dalton amu nucleus Electron o 0 electron cloud outside of nucleus January 16 2014 It is the number of protons that defi nes the element if you change the neutrons it changes the isotope Physical properti es of atoms Atomic number number of protons Mass number atomic mass number of protons neutrons Isotopes atoms with more neutrons Look at Figure 2 9 for the physical and chemical properties of atoms Example Carbon 14 has 6 protons 8 neutrons and Carbon 12 has 6 protons 6 neutrons Chemical properties of atoms Electron shells positions of electrons around nucleus Valence shell electrons outermost most chemical behavior depends on interactions of these electrons Chemical bonds Covalent sharing of electrons between two atoms o Non polar covalent electrons shared equally o Polar covalent electrons shared unequally o They are shown in text by a solid line between two elements o ELECTRONEGATIVITY property of an atom to have a greater attraction to electrons in a bond within a covalent bond and are USUALLY in the upper right corner of the periodic table of elements ex Carbon nitrogen oxygen etc atoms with a high electronegativity pull attract the electrons towards it Ionic electrons are transferred from one atom to another due to electronegativity creates ions No sharing AT ALL Ex Chlorine STRIPS STEALS sodium of an electron to become sodium chloride o Don t play a huge role in biological reaction EXCEPT for proteins Hydrogen bond weak intermolecular forces that involve attractions between and poles example between an H atom and an electronegative atom such as O N S or P o Van der waals forces interactions o Shown in text by a dotted line Look at Figure 2 16 for the difference between the two bonds of Hydrogen and Nitrogen One is covalent and one is a hydrogen bond CHEMICAL REACTIONS making and or breaking chemical bonds leading to production of new compounds Ex C6H12O6 6O2 6H20 6CO2 Identify reactants C6H12O6 602 Products 6H20 6CO2 Elements C H O molecules they are molecules because they are all two or more atoms bonded together even 602 bc it is more than one oxygen bonded together compounds all except 602 are compounds CHAPTER 3 Read pages 46 56 for chapter 3 and pages 58 66 for chapter 4 Why is water important to life biology Without water there would be no life as we know it today usually 90 of cells are water Approx 75 of the planet is water Water is important to moderate temperature because water molecuels can absorb a lot of heat the hydrogen bonds that hold water together take a lot of input of heat to break the hydrogen bonds even though those bonds are very weak In the winter the temperature is warmer by lakes bc the lakes hold the heat from the summer How does the chemical structure of water explain Cohesion that why any water molecules sticks to itself this happens because the formation of hydrogen bonds Adhesion water sticks to other things because it is polar High specific heat it takes a lot of heat to break the hydrogen bonds between water molecules so it can hold and absorb and let off a lot of heat Floating ice hydrogen bonds continue to form in a lattice like structure making it less dense than water water expands when forming ice because the molecules don t move quite as fast so once a hydrogen bond forms They will stay longer so the water molecules are forced apart making it 1 Expand and 2 Less dense than water Hydrophilic interactions they are able to form hydrogen bonds with water attracted to water and water wants to interact with them so a shell of water is formed around them Life is an aqueous solution Most biological chemistry involves solutes dissolved in water Need to calculate concentrations Molecular mass measurement of mass of all ATOMS in a molecule o Example NaCl 23 35 58 daltons Terms for solute concentrations in aqueous solution o Molarity M moles of solute liter o Mole 6 02 x 10 23 objects or Daltons gram similar concept dozen 12 objects SOOO the molar mass of 1 mol NaCl is 58 g TEST YOUR UNDERSTANDING 1 What is the number of atoms present in 12 01 grams of carbon 6 02 X 10 23 atoms 1 mole 1 008 grams of hydrogen 6 02 X 10 23 atoms 1 mole 32 04 grams of sulfur 6 02 X 10 23 atoms 1 mole 2 Make a 1 M solution of NaCl 1 M 1 mol NaCl 1 L water Notes on PH an Buffers Water can dissociate into IONS o 2H20 H3O OH o OR H20 H OH Acid any substance that increases the H in solution o Donate H in aqueous solutions Base any substance that decreases the H in solution o Donate OH or accept H in aqueous solutions Behavior of acids and bases in aqueous solution is CONSTANT 25 degrees C and can be expressed as H OH 10 14 which is a very small Example water 10 7 x 10 7 10 14 Can also be expressed logarithmically Ph potential of hydrogen log H Water log 10 7 7 NOTE Texas surgace water pH range 5 9 Look at Figure 3 10 for every day types of solutions acids bases Buffering Since most living cells exist between pH 6 5 8 Buffering
View Full Document
Unlocking...