BIOL-1101 Exam 1 PDF - Biology Past Paper

BIOL-1101 Exam 1 Elements Pure substances; made of only 1 type of atom or molecule Atomic Number Atoms comprised of: Protons; + charge Electrons; - charge Neutrons; no charge...

BIOL-1101 Exam 1 Elements Pure substances; made of only 1 type of atom or molecule Atomic Number Atoms comprised of: Protons; + charge Electrons; - charge Neutrons; no charge Protons & neutrons in nucleus Electrons in surrounding orbitals Atomic Number # of protons or electrons Atomic Mass # of protons + neutrons Mass average given Isotopes # of neutrons changes; changes atomic mass # protons & electrons remain the same Unstable isotopes = radioactive; emit particles or Atomic Mass energy Electrons Negatively charged particles surrounding atomic nucleus; balance out positively charged protons for stability So small that mass isn’t counted Exist in electron cloud; comprised of energy levels & orbitals Energy Levels: K, L, M, … Orbitals: S, P, D, F K-level lowest energy; contains 2e- of circular S orbital; can contain maximum of 2e- L-level Includes S & P orbitals P orbitals made of ‘dumbbell’ shapes on x,y,z axes Each P orbital can hold 2e-, making total of 6e- S & P orbitals together hold maximum of 8e- Valence Electrons Outermost e- of atom Used in chemical reactions Determine reactivity of atom Reactivity; Bonding Valence electrons cont’d Atoms want valence shell full; will give, take, or share e- to reach stability Nonstable atoms have nonneutral charges and become ions Atoms that give up e- become cations (+) Atoms that take in e- become anions (-) Ionic Bonding 1 metal & 1 nonmetal give/take electrons Cation + Anion = neutral compound E.g.- Na(+1) + Cl(-1) = NaCl The greater the difference in ion charges, the stronger the ionic bond will be Polar bonds Covalent Bonding 2 nonmetals share electrons Makes 3 types of bonds Single; weakest Double; intermediate Triple; strongest Can be polar or nonpolar depending Properties of Water Electronegativity & Polarity Electronegative atoms have high affinity for taking electrons; ex. Halogens (F, Cl, Br, I) and Oxygen Metals on far left of PT are least electronegative; more readily give up e- The greater the difference in electronegativity between atoms in a molecule, the more polar that molecule will be; ex. Water (H2O) Atoms with similar electronegativity will be less polar to nonpolar; ex. H2, F2 Cohesion Water molecules sticking to other water molecules; done with hydrogen bonding Creates surface tension; can be broken by a surfactant Adhesion Water molecules sticking to other polar, non- water molecules Ex. Water sticking to glass The Universal Solvent Water dissolves other polar compounds; hydrophilic compounds, ionic bonds Hydrophobic compounds are generally nonpolar and repel water Water Reactions Dehydration Synthesis Molecules combine together and spit out water molecule Hydrolysis Molecules broken apart by presence of water pH, Acids, Bases, Buffers pH Scale From 0-14 0-6 acidic 7 neutral 8-14 basic/alkaline Acids Release H+ ions (a proton) when dissolved in water ex: HCl = H(+) + Cl(-) Bases OH- (hydroxide ions) absorb H+ ions, reducing acidity of solution Buffers Resist changes in pH when small amounts of acids/bases are added Usually includes a salt Functional Groups Hydroxyl Groups R-OH Single bonded to OH Found in alcohols Simplest = methanol/methylachohol Carbonyl Groups R-C=O Carbon double bonded to oxygen Found in multiple groups of compounds Aldehydes; formaldehyde Esters; make an “L” shape Ketones; make a “T” shape Carboxyl Groups Combination of hydroxyl and carbonyl groups Found in organic acids; formic acid Amino/Amine Groups NH2 Found in amino acids; organic acids (carboxyl group) + amine group Simplest = glycine Macromolecules Carbohydrates Made of carbon, oxygen, hydrogen primarily C-H bonds contain energy; quick usage Monomers = monosaccharides (can be aldehydes or ketones); simple sugars; ring shaped; end with suffix –ose Grouped by # of carbons; ex: Pentose (5), Hexose (6) Monosaccharides combined into disaccharide polymers via dehydration synthesis Ex: Glucose can be made into disaccharides Hexose; has alpha & beta forms determined by position of hydroxyl groups Glucose has carbonyl group Fructose has ketone Galactose is a mirror of glucose Alpha glucose + alpha glucose = Maltose Glucose + Fructose = Sucrose Glucose + Galactose = Lactose Polysaccharides Alpha glucose = branched polymer Starches, glycogen Beta glucose = unbranched polymer Cellulose Macromolecules Lipids Comprised of C, O, H C-H bonds contain energy; long-term storage Hydrophobic; nonpolar Ex: oils, fats, waxes Triglyceride Glycerol + 3 fatty acids Steroids Cholesterol made from saturated fats Hormones Glucose converted into starches, then excess made into triglycerides by liver for energy storage High Density Lipoprotein HDL “Good” cholesterol Low Density Lipoprotein LDL “Bad” cholesterol Macromolecules Proteins Monomers = amino acids Contain amino & carboxyl groups; amine + organic acid Simplest = glycine Peptide bonds link monomers into polymers Polypeptides named by # of amino acids being bonded together Ex: 2 amino acids bound by 1 peptide bond = dipeptide Polypeptide Structures Primary Sequence of amino acids Secondary Primary sequences together in 3D space Alpha helices Beta pleated sheets Tertiary Secondary structures folded back on each other Globular proteins Enzymes Quaternary Multiple tertiary structures together Hemoglobin, hemocyanin Enzymes cont’d Tertiary proteins; catalyze reactions; end in -ase Specific substrates bind to specific active sites Denatured by heat; bonds break, lose function Macromolecules Nucleic Acids 3 major components of nucleotide monomers: Pentose sugar Phosphate group Nitrogenous base Nitrogenous Bases cont’d Purines; 2 ring structure Adenine, Guanine Pyrimidines; 1 ring structure Thymine, Cytosine, Uracil Purines & pyrimidines bond to one another across DNA strands with hydrogen bonds; A&T/U, G&C Deoxyribonucleic Acid (DNA) Double stranded helix Deoxyribose sugar Uses thymine Ribonucleic Acid (RNA) Single strand Ribose sugar Uses uracil