Ch 6: Chemistry in Biology



Ch 6: Chemistry in BiologyDate of Test: ____________6.1 Atoms, Elements, and CompoundsDefine chemistry: the study of matter – its composition and propertiesDefine atom: the smallest unit of matter that still retains the properties of that element; referred to as the building blocks of matterWhat are atoms made of? Protons, neutrons, and electronsDistinguish between protons, neutrons, and electrons based on the following:Protons (p+)Neutrons (n0)Electrons (e-)Electric chargePositiveNeutralNegativeLocation in atomNucleusNucleusOrbits outside of nucleusMass1 amu1 amuInsignificant massAn element is a pure substance that cannot be broken down into other substances by physical or chemical means.How many naturally occurring elements are there? 92Define ion: an atom that has an electric charge due to the loss or gain of electronsHorizontal rows on periodic table are called periods; vertical columns are called groups.Isotopes are atoms of the same element that have different numbers of neutrons, but same number of protons.Isotopes that give off radiation when a nucleus breaks down and can be detected are called radioactive isotopes. These isotopes can be used in medical and other applications.Define chemical bond: the force that holds substances together.Define compound: a pure substance with unique properties that is formed when two or more different elements combineCompounds cannot be broken down by physical means and they always have a fixed ratio for their combination of elementsCovalent bonds form when electrons are shared.Molecules are compounds in which atoms are held together by covalent bonds.Ionic bonds form when electrons are donated due to an electrical attraction between two oppositely charged atoms or group of atoms.Charged atoms or group of atoms are called ions. (Ex: Na+, K+, Ca++, Cl-, and carbonate ion found in living things)Explain van der Waals forces and its importance to water: δ+δ-Covalent bonds do not always attract electrons equally and can cause an unequal distribution of electrons around the nucleus, creating temporary areas of slightly positive and negative charges. These partial positive (δ+) and negative (δ-) regions cause the molecules to attract. This attraction is referred to as van der Waals forces. Van der Waals forces are what attract water molecules together and the reason why water is a good solvent. These forces are weaker than covalent and ionic bonds.6.2 Chemical ReactionsDefine chemical reaction: the process by which atoms or groups of atoms in substances are reorganized into different substancesHow do chemical reactions sustain life? Chemical reactions break down molecules and make new ones necessary for growth, development, reproduction, and adaptation.How are chemical reactions written? Reactants ProductsDefine reactant: the starting substances of a chemical reactionDefine product: the substances formed during a reactionGive an example of a chemical reaction that occurs in your body.C6H12O6 + 6 O2 6 CO2 + 6 H2O + ATP(sugar + oxygen carbon dioxide + water + energy releasing molecule)What does it mean for a chemical reaction to be balanced? The number of each atom on the reactant side must equal the number of each atom on the product sideWhy are chemical reactions always balanced? Matter is always conserved: It is never created nor destroyed, just rearranged.What do most molecules in living things need in order to undergo chemical reactions? energyDefine activation energy: the minimum amount of energy needed for a chemical reaction to occur endothermic exothermicAn exothermic reaction releases heat energy (feels hot).An endothermic reaction absorbs heat energy (feels cold).What is a catalyst? A substance that lowers the activation energy needed to start a chemical reaction; thereby making the reaction happen faster.What is an enzyme? A catalyst that speeds up the rate of chemical reactions in biological processesHow does an enzyme speed up a chemical reaction? The enzyme changes the shapes of the reactants causing their bonds to break easier.What is the enzyme found in saliva and what chemical reaction does it speed up?The enzyme amylase in saliva speeds up the breakdown of a starch called amylose.6.3 Water and SolutionsThe properties of water make it well suited to help maintain homeostasis in an organism.Water is a polar molecule, meaning it has an uneven distribution of charges (refer to question #18 and van der Waal’s force)Solutions are homogeneous mixtures formed when a solute is dissolved in a solvent. (uniform in composition)Mixtures are heterogeneous when components remain distinct.Acids are substances that release hydrogen ions (H+) into solutions. (pH<7)Bases are substances that release hydroxide ions (OH-) into solutions. (pH>7)pH is a measure of the concentration of hydrogen ions in a solution.6.4 The Building Blocks of Life (Macromolecules):Define biochemistry: study of chemical processes within and relating to living organismsDefine organic chemistry: the study of organic compounds - those compounds containing carbon The element carbon is a component of almost all biological molecules.Define macromolecule: large molecules that are formed by joining smaller organic molecules togetherKnow the 4 types of macromolecules that are in cells, an example of each, the function of each, and the atoms that each contains. MacromoleculeExampleFunctionAtomsCarbohydratesGlycogen (sugar)Cellulose in plantsStore energy Provide structural supportC, H, OLipidsFats (triglycerides)Store energyProvide barriersC, H, PProteinsEnzymes, muscles, skinTransport substances Speed up reactionsProvide structural support Make hormonesC, H, O, N, SNucleic AcidsDNAStore and communicate genetic informationC, H, O, N, PKnow the relationship between the following:macromoleculesmoleculesatomsProtonselectronsneutronscells make upwhich make upwhich make upwhich make up ................
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