BIOL 1107 1st Edition Exam 1 Study Guide Lectures 1 9 Lecture 1 January 22 Chemical bonds are attractions that bind atoms together The electronegativity is how strong the electron pull between two atoms is Polarity refers to the difference across something Polarity is one of the reasons our body needs water because it allows cells to move ions and create an action potential Hydrogen Bond a weak attraction between two molecules Polar Covalent Bond a covalent bond in which electrons are unequally shared between atoms Non Polar Covalent Bond a covalent bond in which the electrons are equally shared between atoms Ionic Bond transfer of electrons causing atoms to remain associated due to their opposite electric charges Lecture 2 January 24 Chemical reactions occur when one substance is combined with another atoms are rearranged or when one substance is broken down due to molecules being split forming another substance Chemical reactions are controlled by enzymes and can either build more complex substances or break them down Complexity is when the products contain more energy than the reactants because heat was added creating more chemical bonds Molecular Weight sum of the mass numbers of all atoms in a molecule one mole 6 022x1023 molecules moles are expressed in grams Molarity the concentration of a substance in a solution number of moles per liter Anabolic Endothermic Reactions building reactions that make more complex substances by absorbing energy Exothermic Reactions break down substances by releasing energy Lecture 3 January 27 Hydrogen bonding makes it possible for any charged or polar molecule to dissolve in water and creates special characteristics such as density For example polarity only allows molecules to get so close and not be able to get any denser Hydrophilic attraction to water ions and polar molecules Hydrophobic repel from water uncharged and nonpolar compounds The pH scale is logarithmic Greater H concentration lower pH more acidic Lower H concentration higher pH more basic alkaline Buffers compounds that minimize changes in pH Chemical reactions have reactants and products and are driven by energy the capacity to go work or supply heat Energy exists as stored potential or as active motion Electrons have the greatest potential energy in the outermost electron shells when they are further away from the nucleus It is all about the POSITION of electron across the bond Heat is the thermal energy transferred between objects of different temperatures The First Law of Thermodynamics energy is conserved energy cannot be created or destroyed only transferred or transformed The Second Law of Thermodynamics entropy disorder always increases Things have to be maintained so they do not go into a state of disorder Lecture 4 January 29 Amino acids are the simplest molecule of a protein They are monomers the simplest form of a particular substance that link to form larger substances Every amino acids has an amino group and a carboxyl group however it is the side chains that make all 20 amino acids unique from each other by changing reactivity Dehydration synthesis reactions connect amino acids to build a protein by removing a water molecule Proteins are involved in structure mobility catalysts enzymes repair signaling pathways and energy production Hydrolysis is the reverse of a dehydration synthesis reaction adding water to break apart the protein There are 20 amino acids Lecture 5 January 31 The amino group end of a polypeptide is called the N terminus and the Carboxyl group end of the polypeptide is called the C terminus The N terminus and C terminus are important for solubility in water Secondary Structure formed by hydrogen bonds between carbonyl group of one amino acid and amino group of another Forms helix and pleated sheets Tertiary Structure interactions between R groups or R groups and peptide backbone Side chains allow polypeptide to interact with each other o when secondary structures interact Quaternary Structure have to have at least two polypeptides at tertiary level Protein folding is often spontaneous because hydrogen bonds and van der waals interactions make the folded molecule more energetically stable than the unfolded molecule A denatured unfolded molecule is unable to function normally Proteins called molecular chaperones help proteins fold correctly in cells Shape is everything Prions are improperly folded forms of normal proteins that are present in healthy individuals The amino acid sequence doesn t differ from normal protein just the shape Enzymes enhance the rate of a chemical reaction o Initiation have active sites where substrates can bind forming enzyme substrate complex o Transition State Facilitation interactions b w enzyme and substrate lower activation energy required o Termination products have lower affinity for active site and are released Enzyme is unchanged after reaction Competitive Inhibition occurs when a molecule similar in size and shape to substrate competes with substrate for access to active site Allosteric Regulation occurs when molecule causes change in enzyme shape by binding to the enzyme at a location other than the active site activate or deactivate enzyme Lecture 6 February 3 The building blocks of nucleic acids are nucleotides DNA is a double stranded molecule due to hydrogen bonding and RNA is single stranded The 5 end of a nucleotide binds to the 3 end of another nucleotide giving DNA directionality Carbohydrates are highly variable in structure Monosaccharides are monomers that polymerize to form polymers called polysaccharides and are joined by glycosidic linkages Carbs provides structural support to the cell indicates cell identity stores chemical energy due to chemical bonds ext The shift of one hydroxyl group to a different position on a carbon completely changes the family of the carbohydrate Simple sugars polymerize when a condensation reaction occurs between two hydroxyl groups resulting in a covalent bond called a glycosidic linkage Types of Polysaccharides Plants store sugar as starch mixture of branched and unbranched glucose polymers Animals store sugar as glycogen highly branched glucose polymer easier to alter Cellulose is a structural polymer in plant cell walls polymer of glucose monomers Chitin is a structural polymer found in fungi cell walls Bacterial cells walls get structural support from peptidoglycan Lecture 7 February 7 Starch is almost pure glucose it is a carbohydrate at its most simplest from