Bio1107K, Week 2 Notes
Bio1107K, Week 2 Notes BIOL 1107K
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This 3 page Class Notes was uploaded by Bethany B. on Sunday August 28, 2016. The Class Notes belongs to BIOL 1107K at Georgia Gwinnett College taught by Latanya Hammonds in Fall 2016. Since its upload, it has received 4 views. For similar materials see Principles of Biology I w/Lab in Biology at Georgia Gwinnett College.
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Date Created: 08/28/16
8.28.16 Biology1107KNotes[Week2] LectureNotes Periodic Table s p d f represent the orbitals of an atom and are organizedon the table Octet Rule (“Fat & Happy”)—they want afullouter shell(some elements don’t want eight electrons; hydrogenonlywants two) Bonds 3 Major Types of Bonds:Covalent,Ionic,Hydrogen o Covalent—strongest bondin biology; one in which the electrons are shared Polar—water,electrons are not sharedequally because oxygenis more electronegative andthe electrons gravitate towards the oxygenmolecule.[partial negative charge aroundoxygen andpartialnegative charge aroundthe two hydrogens] Nonpolar—In CCl4,the electrons gravitate towards the chlorinemolecules onthe outside.Dipoles canceleach other out so the whole molecule is nonpolar.[bonds- polar, molecule-nonpolar] Organic molecules are nonpolar; bases are C (2.4 electronegativity) and H (2.2 electronegativity) o Octane (C8H18) does not dissolve in water [Hydrophobic] o Ionic—electrons are stolenor given away Elements to the left (s) like to give electrons while elements on the right (p) take electrons. Fluorine is the most electronegativethingon the table Anythingin the 7 period(where fluorine is) o Hydrogen—the bonds that link two water molecules together,representedas dots or dashes; they are not very stable andreversible/temporary; in order to have ahydrogen bondyou needmore than onemolecule Hydrophilic—polar (has oxygenandsuch) Hydrophobic—nonpolar (onlycarbons andhydrogens) Hydrogen bonds they are the weakest type of bonds but we are still water basedlife forms because they are breakable. A single water molecule can have upto four hydrogen bonds Cohesion (water to water,straw),adhesion (water to somethingelse,water strider bugs) Surface Tension is where the hydrogen bonds don’t break easily. Properties of Water 1. Surface Tension 2. High Specific Heat—the energyfrom the sun is beingabsorbedby the water at the beach, makingthe surroundinglandcooler. 3. Evaporative Cooling 4. Density 5. Solvent of Life:solute—thesubstancebeingdissolved,solvent—thedissolvingagent a. Hydration shell:when an ionic compoundis dissolvedin water,each ion is surroundedby a sphere of water molecules calledahydration shell b. Water is a versatile solvent due to its polarity**** 6. Hydrophilic andHydrophobic Substances a. Hydrophilic substances is one that has an affinity for water b. Hydrophobic substances is one that does not have an affinity for water c. Colloid—astable suspension of fine particles (micelles) in aliquid *GoodTo Know:Lotions that sellthe vitamins to make healthier skin are allfalse because the outer layer of skin is all dead. You are not doinganythingby rubbingvitamin c on your face.* Acidic andBasic Conditions Affect LivingOrganisms A hydrogen atom in ahydrogen bondbetweentwo water molecules can shift from one to the other pH=2 [H ]=1 x 10 M > [H ]=1 x 10 M -11 Water is in a state of dynamic equilibrium in which water molecules dissociate at the same rate at which they are beingreformed Chapter2 Notes Section 2.1Properties of Atoms Atoms consists of positively chargedprotons,negatively chargedelectrons,andneutralneutrons. The protons andneutrons are foundin the nucleus while the electrons are movingaroundthe nucleus in orbitals. The number of protons determines the identityof an atom. The number of protons andneutrons together determines themass of an atom. The number of protons versus the number of electrons determines the chargeof an atom. Section 2.2Molecules andChemicalBonds Valence electrons occupy theoutermost energy level(shell) of an atom anddetermine the ability of an atom to combine with other atoms to form molecules Covalent bond—thesharingof electrons between atoms to form amolecular orbital Polar covalent bond—twoatoms do not share electrons equally Ionic bond—the attraction of oppositelychargedions Electronegativity—theability of the atom to attract electrons (increases as you go across the table to the right andup) Section 2.3Water:The Medium of Life Water is a polar molecule. Hydrophilic molecules dissolvereadily in water.Hydrophobic molecules in water tendto associate with one another to minimize contact with water. A hydrogen bondresults when ahydrogen atom covalently bondedto an electronegativeatom interacts with an electronegativeatom of another molecule. 2 Water forms hydrogen bonds,which helps explain its high cohesion,surface tension,andresistance to rapid temperature change. The pH of an aqueous solution is ameasure of the acidity of the solution. Section 2.4Carbon:Life’s ChemicalBackbone A carbon atom can form upto four covalent bonds with another atom. The geometryof these covalent bonds helps explain the structuralandfunctionaldiversity of organic molecules. Section 2.5Organic Molecules Amino acids are linkedby covalent bonds to form proteins. An amino acid consists of a carbon atom attachedto a carboxylgroup,an amino group,a hydrogen atom,andaside chain. The side chain determines the properties of an amino acid. Nucleotides assemble to form nucleic acids,which store andtransmit genetic information. Nucleotides are composedof a5-carbon sugar,a nitrogen-containingbase,anda phosphate group. Nucleotides in DNA incorporate the sugar deoxyribose,andnucleotides in RNA incorporatethe sugar ribose. The bases are pyrimidines (cytosine,thymine,anduracil) and purines (guanine andadenine). Sugars are carbohydrates,molecules composedof C,H, and O atoms,usually in the ratio 1:2:1, and are a source of energy. Monosaccharides assembleto form disaccharides or longer polymers calledcomplex carbohydrates. Lipids are hydrophobic. Triacylglycerols storeenergy andare made upof glycerolandfatty acids. Fatty acids consist of a linear hydrocarbon chainof variable length with acarboxylgroupat one end. Fatty acids are either saturated(no carbon-carbondouble bonds) or unsaturated(oneor more carbon-carbon doublebonds). The tight packingof fatty acids in lipids is the result of van der Waals forces,a type of weak, noncovalent bond. Section 2.6How Did Molecules of Life Form? In 1953, Stanley Miller andHarold Urey demonstratedthat amino acids can be generatedin the laboratory in conditions that mimic those of the early Earth. Life likely originatedon Earth by aset of chemicalreactions that gave rise to the molecules of life. Other experiments haveshown that sugars,bases,andlipids can be generatedin the laboratory. Once the buildingblocks were synthesized,theycouldjoin together in the presenceof clay minerals to form polymers. 3
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