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U-M BIOLOGY 172 - Lecture 3

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Lecture 3 ReviewI. Types of Chemical BondsA. Covalent1. atoms unpaired electrons are shared by both the nuclei to fill their orbitals2. Atoms share pairs of valence electrons3. Polari. electrons are shared unequallyii. presence of a highly electronegative atom that has a stronger pull a. Electronegative atom will have a partial negative charge while the other atoms will have a partial positiveb.O>>N>C~H4. Nonpolari. electrons are shared equallyB. Ionic1. Electron transfer 2. Cation (+) and anion (-)3. they are salts4. form when electrons are completely transferred from one atom to anotherC. Hydrogen1. weak bonds2. attraction of the partial postitve hydrogen bonds attract to the partial negative oxygen bonds3. forms between polar moleculesD .Van der Waals forcesII. The Properties of WaterA. life originated in and based on water because water is a great solventB. H-O bonds in water are polar covalent1. electrons are in constant motion and as a result they are not equally distributed2. Even in nonpolar covalent bonds there are certain areas of + and - chargesHI! I’m Van der and I stareat Waals1. Oxygen is more electronegative then H giving it a partial negative bond and Hydrogen a partial postive2. Leads to Oxygen causing a larger attraction to the electrons making the sharing unequalC. Water is polarD. Hydrogen bonds form between water moleculesE. Ions dissolve in waterF. Non polar Molecules do not dissolve readly in waterG. Cohension and Adhension are the reasons why meniscus frooms where water mets a solid surface1. Adhensioni. Water molecules at the surface adhere to the glass allowing them to resist the downward pull of cohension2. Cohesioni. Because water molcules at the surface hydrogen bonds with water molecules below them, they experience a net downward pullH. Crsytal Lattice1. forms between water molecules in ice2. does not form in liquid waterI. Liquid water is denser than ice which is the reason as to why it floatsJ. Hydropjopic Interactions1. non polar molecules or nonpolar regions of molecules associate in polar envionrmentsi. critical for protein folding and membrane structure ii. the driving force for protein foldingK. Chemical properties of water that support life1. Cohension (hydorhen bonds)2. Moderation of temperature (high spectfic heat)3. Insulation by floating ice (reduced density in solid)4. Solvent for polar compoundsIII. pH scaleA. pH scale= -log[H+]B. an acid increases [H+]C. a base decrease [H+]D. a buffer minizies changes in [H+] and [OH-]IV. Functional GroupsA. AminoB. CarboxylC. CarbonylD. HydroxylE. PhosphateF. SulfhydrlV. Biological Macromolecules A. Proteins: enzymes, structural proteins, transport proteins, signaling proteinsB. Carbohydrates: fuel and building materialC. Nucleic Acids: nucleotides (energy and signaling), DNA = genetic information; RNA D. intermediary between DNA and proteinE. Lipids: fuel storage, membranes, hormonesMonomers v. Polymers Protiens Amino Acids ProteinsNucleic Acids Nucleic Acids Nucleic AcidsCarbohydrates Monosaccarides Polysaccerides*lipid diverse calls of macromoles makes them no true monomer/polmer relationship because they are no composed of repeating subunitsVI. ProteinsA. Catlysis(Enzymes)- speed up chemical reactionsB. Defense- antibodiesC. Movement-motoe and contractile proteins move the cell or molecules within the cellD. Signaling- Proteins convey signals between cellsE. Structure- structural proteins define cell shape and comprise body structresF. Transport- transport proteins carry materials: membrane proteins control molecular movement into and out of the cellG. Hormones- many hormones are proteins, Hornmonesare important chemical signals between different cell typesH. composed of Amino Acids1. 20 different combonations2. Each has a carboxyl group and an amino group3. differ in charge, polarity and size, due to R groupdI. Non-Ionized form of amino acidJ. Ionized form of amino acidK. Structure1. Primary Structurei. linear sequence of amino acidsii. held together by covalent bonds(peptide bonds)2. Secondary Structurei. interaction betwenn atoms in backbonesii. held together by hydrogen bondsiii generate coiled or folded regions3. Tetritary Struture i. held together by interactions bwteen atoms in R groupd or between R groups and the polypeptide backboneii. Hydogren bond btween side chain and carboxyl groupiii. Hydrogen bond between two side chainsiv. hydrophnic interactionsv. disulfate bondvi. ionic bondvii. a single polypeptide chain with one or more secondary strurcturesviii. very diversea. can be composed of beta and alpha helicaseb. and can have disulfide bonds4. Quaternary Structurei. more than 1 polypeptide chain interaction to from a single structureii. held together by covalent, ionic, hydrogen, and/or Van der Waals interactionsX. Synthesis of Proteins(Polypeptides)A. amino acids linked between carboxyl and amino acids groups to make a peptide bondB. polypeptides have an amino end and a carboxyl endC. a polypeptide is flexible and has directionality and its side chains extend out rom the backboneD. because the amino acid R-groups affect a polypeptides size, shape, chemical reactivity,and interaction with water, hust single amino acid change can radically alter protein function. E. each carbonyl group in the backbone orms a hydrogen bond with an amide group four resides awayVII. Fuctional Grups Affect ReactivityA. R groups differ in their size, shape, reactivity, and interaction with water1. Non-polar R groups(uncharged); Hydrophobis and do not form hydrogen bonds. Coalesce in water, saturated hydrocarbons or ring structrures2. Polar R groups(charged): hyrdorphillic, from hydrogen bonds and readily dissolve in water, contain S, O or N at the end (in contact with water)B. Amino acide with hydroxyl, amino. Carboxyl, or sulfhydryl functional group in their side chains are more chemically reaction than those with side chains composed of only carbon and hydrogen atoms1. thses side chains cannont form hydrogen bonds with water hydropobicC. Increase electronegativity of oxygen and nitrogen compared to carbon andhydrogen thses side chains can undergo hydrogen bonding with water so they are hydrophilicD. Electrically Charged side Chains1. since they are charged they are very hydrophilicVIII. How do Amino Acids Link to from proteinsA. Amino acids polymerize to form proteins1. polymerication reactions require energy and are not spontaneous IX. Biological MacromoleculesA..


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