Foundations of Biology 1 - Chapter 2 - Chemistry
Foundations of Biology 1 - Chapter 2 - Chemistry Biology 221
Popular in Foundations of Biology 1
Popular in Biology
verified elite notetaker
This 7 page Class Notes was uploaded by Lexie Kostreva on Friday September 16, 2016. The Class Notes belongs to Biology 221 at University of Wisconsin - Eau Claire taught by Daniel P. Herman in Fall 2016. Since its upload, it has received 146 views. For similar materials see Foundations of Biology 1 in Biology at University of Wisconsin - Eau Claire.
Reviews for Foundations of Biology 1 - Chapter 2 - Chemistry
Report this Material
What is Karma?
Karma is the currency of StudySoup.
Date Created: 09/16/16
Foundations in Biology 1 Chapter 2 - Chemistry The chemical basis of life o Definitions Matter Anything that has mass and occupies space Atoms The smallest functional unit of mass Molecules Two or more atoms bonded together Atoms o Composed of sub atomic particles o Protons Positive o Neutrons Neutral o Electrons Negative Electrons found in orbitals around the nucleus An electron shell = 1 or more orbitals The inner shell has one orbital that can hold 2 electrons The second shell has four orbitals Each orbital can hold 2 electrons Electrons in the outer orbital are valence electrons Valence electrons participate in bond formation Periodic Table o Atomic number o Atomic mass o Rows (Periods) Number of electron shells o Columns (Groups) Number of valence electrons o Isotopes Elements that have a different number of neutrons; 12C and 14C o Radioisotopes Unstable isotopes that emit subatomic particles and/or radiation Numerically Speaking o Atomic/molecular masses are measured in daltons (Da) or kilodaltons (kDa) 1 Da = the mass of a hydrogen atom (or 1/12 the mass of a carbon atom) o Mole The number of atoms in 12 grams of carbon A mole of any substance contains 6.022 * 10^23 atoms/molecules o Avagadro’s number23 6.022 * 10 o What elements are most abundant in living organisms? Oxygen Carbon Hydrogen Nitrogen o Molecules and compounds Molecule Two or more atoms bonded together Compound Molecule composed of two or more different elements Molecular formula C 6 12 6 The physical properties of a compound are different from the physical properties of the separate elements Sodium (Na) o Soft, silvery metal that ignites in water Chlorine (Cl) o Yellow-green gas Sodium chloride (NaCl) o Salt Covalent bonds Formed when atoms share valence electrons o Single bond One pair of electrons shared between atoms o Double bond Two pairs of electrons shared between atoms o Octet rule Many atoms found in living organisms can have up to eight electrons in their outermost shell Atoms are most stable when that shell is filled o The electronegativity of the atoms determines how the electrons are shared in covalent bonds Nonpolar covalent bond The electrons are shared equally between both atoms orbits Polar covalent bonds One atom has the electron in its orbit for longer than the other atom does Partial positive and partial negative charges Polar molecules and hydrogen bonds Hydrogen bond o Weak attraction between a hydrogen atom from a polar molecule and an electronegative atom o Can occur between molecules or within a single molecule o A few hydrogen bonds can allow molecules to interact and then separate The interaction between enzymes and their substrates o Many hydrogen bonds result in a strong force Can contribute to maintaining the 3D structure of a molecule Van der waals forces Weak attractive force between nonpolar molecules that are within 5 nm o Even weaker than a hydrogen bond o Cumulative effect can be strong Nanometer -9 o 1*10 Fluctuating dipole o Can change between nonpolar and polar depending on where the electrons are Ionic bonds Ion o An atom that has gained or lost one or more electrons Cation o Atom with positive charge o Lost one or more electrons Anion o Atom with negative charge o Gained one or more electrons Ionic bond o A bond formed between a cation (+) and an anion (-) o Weaker than covalent bonds, but stronger than hydrogen bonds Molecular Shapes Chemical reactions Occurs when one or more substances are changed into other substances through the formation or breaking of chemical bonds Characteristics of chemical reactions Require energy (heat) for molecules to move and encounter each other Many reactions require catalysts o Most biological reactions require catalysts Usually proceed in one direction until equilibrium is reached o Biological reactions don’t usually reach equilibrium o The product of one reaction is the starting point for the next reaction Usually occur in aqueous environments o Water is the solvent of life Properties of water Living organisms composed of up to 95% water 60-70% of human body weight is due to water o Brain – 70% o Blood – 80% o Lungs – 90% o Bone – 20% Many organisms live in aqueous environments Cell/tissues surrounded by aqueous environments Biologically important chemical reactions happen in aqueous environments o Cytoplasm Aqueous solution containing dissolved molecules that can undergo chemical reactions Solutions Solvent o Liquid Solute o Substance dissolved in the solute Aqueous solutions o Solutions where the solvent is water Like dissolves like o Water is a polar molecule = molecules with ionic or polar covalent bonds dissolve in water = hydrophilic o Molecules with nonpolar covalent bonds don’t dissolve in water = hydrophobic Amphipathic molecules Both polar and nonpolar regions Bilayer o Polar heads to the outside o Nonpolar tails to the inside How do you talk about solutions? Concentration o Amount of solute dissolved in a unit of volume of solution o Can be expresses in several ways 5 g/l, 5 mg/ml, etc. Weight percent (g/100ml) o 20% glucose solution, etc. Molarity o Number of moles dissolved in 1 liter of solution o Moles/volume (L) = molarity Molecular mass o Grams/molar mass = moles o Na = 22.99 o Cl = 35.446 States of water (pure) Solid o 0C, ice o Hydrogen bonds between water molecules form complexes Liquid o 0C < water < 100C o Transient formation/breaking of hydrogen bonds between water molecules Gas o 100C, water vapor o Heat energy breaks hydrogen bonds between water molecules and allows water molecules to escape Properties of water Heat of vaporization o Heat required to vaporize 1 M of substance at its boiling point Heat fusion o Amount of heat energy that must be released to change from liquid to solid Specific heat o Amount of heat energy required to raise the temperature of 1g of substance 1C Heat capacity o Amount of heat required to raise the temperature of an entire object or substance Colligative properties o Properties that depend only on the total number of dissolved solutes If a solute is present, the freezing point will go down and the boiling point will go up Biological functions of water Solvent o Permits reactions between molecules that wouldn’t be possible in the non-dissolved state o Particles in dehydration and hydrolysis reactions Cohesion o Attraction of water molecules to each other o Surface tension Adhesion o Attraction of water molecules to non-neutral surfaces pH Water can ionize at low levels The concentration of both H and OH is 10 in pure water Acids o Substances that release hydrogen ions o Strong acids almost completely dissociate in water; weak acids do not Bases o Substances that bind hydrogen ions Maintaining pH is important Hydrogen ions and hydroxyl ions can bind to many kinds of ions and molecules, which can affect o Shapes and functions of molecules o Rates of chemical reactions o Ability of two molecules to bind and/or interact o Ability of ions/molecules to dissolve in water Many biological processes function best within a narrow pH range Buffer o Minimizes pH changes by absorbing or releasing hydrogen ions o Composed of weak acid and its related base Bicarbonate buffering system Functions in the kidneys of mammals to help maintain blood pH