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BCH 351 Exam 1 questions and correct answers graded A+
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BCH 351 Exam 1 questions and correct answers graded A+
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BCH 351 Exam 1Hydrocarbons are ... - correct answer ✔✔nonpolar, hydrophobic
5 Functional Groups - correct answer ✔✔amino, hydroxyl, sulfhydryl, phosphoryl, carboxyl, methyl
Amines - correct answer ✔✔nitrogen joined to at least one alkyl group
amide - correct answer ✔✔have a carbonyl group between the nitrogen and R group
functional group characteristics - correct answer ✔✔- contain electronegative atoms (O,N,S)
- usually electrically charged or polar
- make organic molecule amphiphathic
- create multifunctional molecules that increase functional diversity
- provide sights for intra and inter molecular interactions such as hydrogen bonding and ionic
interactions
types of chemical interactions - correct answer ✔✔covalent, ionic, hydrogen bonds, van der Waal,
hydrophobic effects
covalent bonds - correct answer ✔✔formed by atoms sharing valence electrons and fill each atoms
outer shell.
can be polar or nonpolar depending on if atoms are shared equally or not
polar covalent bond - correct answer ✔✔electrons are shared unequally. electronegativity >0.5
nonpolar covalent bond - correct answer ✔✔electrons are shared equally. electronegativity <0.5
common polar covalent bonds - correct answer ✔✔C-O, O-H, N-H
,ionic interactions - correct answer ✔✔also called charge-charge interactions or salt bridges. Occur
betwen opposite charged atoms or groups. Ex: Na+ and Cl-.
Electronegativity >2.0 (usually between most and least electronegative)
hydrogen bonds - correct answer ✔✔form when a hydrogen that is covalently bonded to an
electronegative atom is in proximity to another electronegative atom. Partial charges
strong hydrogen bond - correct answer ✔✔linear
weak hydrogen bond - correct answer ✔✔angled
van der Waals interactions - correct answer ✔✔occur between neutral molecules/atoms by temporary
dipole moments because of fluctuation in electron clouds. Temporary polarization
Where does van der Waals interactions occur - correct answer ✔✔maximum attraction occurs at a
distance slightly greater than the sum of the van der Waals radii of the two atoms
hydrophobic effects - correct answer ✔✔due to the tendency of nonpolar molecules to pack close
together away from water. Main factor behind protein folding, protein-protein association, formation of
lipid micelles, and enzyme-substrate complex formation
structure and chemistry of water - correct answer ✔✔unequal electron distribution, O is more
electronegative than H. Angle of H-O-H bonds is 104.5. H2O exhibits permanent dipole moments
hydrogen bond between water molecules - correct answer ✔✔each water molecule can form up to 4
hydrogen bonds
2 H donor sites
2 H acceptor sites
, water as a solvent - correct answer ✔✔good solvent for ionic and polar substances (amino acids and
peptides, small alcohols, carbohydrates). Poor solvent for nonpolar substances (hydrocarbons, aromatic
rings, amphipathic molecules)
Limonene - correct answer ✔✔cannot form H-bond with water
nucleophiles - correct answer ✔✔electron-rich, either negatively charged or have unshared pairs of
electrons. Water is a nucleophile
common nucleophilic atoms - correct answer ✔✔O, N, S, C
electrophiles - correct answer ✔✔positively charged molecules
ionization of water - correct answer ✔✔H2O <--> H+ + OH-
water ionization constant (25C, 55.5M)
Kw= [H+][OH-]=1.0e-14 M^2
[H+] & [OH-] are reciprocally related
pH scale - correct answer ✔✔the acidity or basicity of an aqueous solution depends on the
concentration of hydrogen ion [H+] and can be described by a pH value
acids are proton donors and bases are proton acceptors
pH equation - correct answer ✔✔pH = -log[H+] = log 1/[H+]
strong acids - correct answer ✔✔acids that completely dissociate in water
weak acids - correct answer ✔✔acid that partially dissociate in water, extend of dissociation is
determined by pH of solution
Weak Acid Importance - correct answer ✔✔- many biological molecules or their components are weak
acids (amino acids, DNA, RNA)
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