BIOL 120 Final Study Guide Cells and Cell theory Cell Theory all organisms are made of cells and all cells come from preexisting cells o Discovered by Louis Pasteur Cell a highly organized compartment bounded by a plasma membrane Basic atomic Structure Element a substance that can t be broken down into another substance by chemical reactions Atomic number number of protons in the nucleus Atomic mass the number of protons and neutrons Isotopes an atom with the same number of protons but a different number of neutrons o i e Carbon has 6 p and 8n At Wt 14 and Carbon has 6 p and 6 n At Wt 12 Protons positively charged particles Neutrons neutral particles Electrons negatively charged particles Molecule a substance made from two or more atoms of similar or different types form when atoms bond to each other o Most important to life is water because it forms hydrogen bonds Energy the capacity to do work or supply heat and is either stored potential energy or active motion Chemical energy potential energy that is stored in chemical bonds ATP Thermodynamics o 1st law energy cannot be created or destroyed o 2nd law spontaneous natural processes increase entropy overall Chemical Bonds Chemical reaction when an atom gives up gains or shares one or more electrons with another atom Covalent Bond each atom s unpaired valence electrons are shared by both nuclei to fill their orbital o Non polar equal electronegativity o Polar unequal electronegativity o Ionic bond results from the attraction of a cation and anion o Ion an atom or molecule that carries a charge from either losing or gaining an electron o Cation an atom that loses an electron and becomes positively charged o Anion an atom that gains an electron and becomes negatively charged Water Most important chemical property can form hydrogen bonds A great solvent due to the covalent bonds being polar it can bond to other atoms Hydrogen bonds the weak electrical attractions between the partially negative oxygen of one molecule and the partially positive hydrogen of a different water molecule o Hydrophilic can dissolve water loving i e sugar o Hydrophobic uncharged and nonpolar compounds that repel from water i e oil fat Functional Groups Amino and carboxyl groups gain or lose protons NH2 or NH3 amino acids Carbonyl groups site of reactions that link molecules into larger more complex compounds COOH Hydroxyl groups acts as weak acids OH Phosphate groups Have two negative charges needed for ATP and nucleic acid Sulfhydryl groups atoms linked together through disulfide bonds the SH in proteins Hydrocrabons molecules consisting only of C and H nonpolar and other functional groups add chemical properties to it Carbohydrates monosaccharides one sugar molecule Polysaccharides many sugar molecules Functions o raw material for synthesizing other molecules o provide cell structural support can indicate cell I D o store chemical energy needed for cell functions o Molar ration C H O 1 2 1 Glycosidic linkage a covalent bond between two hydroxyl groups occurring from a dehydration reaction that causes simple sugars to polymerize Nucleic Acids Nucleotides consist of a pentose sugar 5 carbon phosphate group bonds to C5 and a nitrogen containing base bonds to C1 Nucleic Acid a polymer of bonded nucleotides that go through a condensation reaction two types of nitrogenous bases o Purines double ring structure Adenine Guanine o Pyrimidines single ring structure Thymine only in DNA Cytosine Uracil only in RNA DNA o primary structure consist of a sequence of nitrogen containing basis ATGC o Secondary structure consist of 2 DNA strands running in opposite directions o Watson and Crick DNA strands run in opposite directions of each other Sugar phosphate back bones are hydrophilic and face the exterior of the structure Nitrogenous base pairs face interior hydrophobic Purines always pair with pyrimidines and not with themselves and vice versa A T has a two hydrogen bond C G has a three hydrogen bond DNA has different size grooves major and minor DNA can store and transmit biological information o Strands grow in 5 to 3 direction o Chargaff s rule equal proportions of Purines A and G and Pyrimidines C and T amount of adenine amount of thymine amount of cytosine amount of guanine o DNA is a double helix A forms 2 hydrogen bonds with T C forms 3 hydrogen bonds with G DNA Replication Occurs in interphase DNA copies are semiconservative part of the old strand bonded with new strand Requires o Paternal DNA to copy and primer o Enzymes to copy DNA o NTPs building blocks to make copy of DNA Process o Initiation o Elongation o Termination Process is Semi discontinuous o Leading strand 5 3 synthesized continuously o Lagging Strand 3 5 synthesized discontinuously with multiple priming events copies in short fragments Okazaki Fragments main replication polymerase DNA polymerase epsilon and DNA polymerase delta RNA o Same as DNA except Contains Uracil instead of Thymine Single stranded Contains ribose instead of deoxyribose RNA molecules act as links between genes Messenger RNA mRNA carries information from DNA to site of protein synthesis o Enzyme RNA polymerase synthesizes RNA according to the information given through the sequence of bases in a gene o After RNA synthesis it is processed in the nucleus and then used for protein synthesis in cytoplasm tRNA bring amino acids to the site of polypeptide synthesis based on codon on mRNA o codon genetic code which is a group of 3 bases on mRNA that tRNA recognizes o mRNA and t RNA pair up rRNA synthesizes ribosomes Lipids Lipids loosely defined group of molecules with one main chemical characteristic insoluble in water examples fats oils waxes steroids Etc Made from o Fatty Acids long chain hydrocarbons with COOH at one end Saturated no double bond between carbon atoms high melting point animal origin i e butter Unsaturated 1 or more double bonds low melting point plant origin i e olive oil Monounsaturated fatty acid with one double bond Polyunsaturated fatty acid with more than one double bond Trans fat fats produced industrially Phospholipids consist of 2 fatty acids joined to a polar head phosphate and are the principal components of cell membranes o form a bilayer membrane and the tails hydrophobic of fatty acid touch and heads hydrophilic are opposite each other Amphipathic part water soluble and part water insoluble hydrophilic and hydrophobic Proteins o protein is composed of amino acids made from RNA in the cytoplasm o Amino