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ACS Biochemistry: Questions And Accurate Answers
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ACS Biochemistry: Questions And Accurate Answers
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ACS Biochemistry: Questions And Accurate AnswersStrength of bonds found in biochemistry Right Ans - 1. covalent (C-H)
2. covalent (O-H)
3. Ionic Interactions
4. Ion-dipole
5. Hydrogen bonds
6. Van der Waals interactions
hydrophilic Right Ans - tending to dissolve in water (water-loving). Ex.
ionic and polar substances
Examples of hydrophilic molecules include Right Ans - polar moelcules like
alcohols (ethanol) and ketpons (acetone)
or ionic compounds like (KCl) or sugars, AA, or phosphate esters
hydrophobic Right Ans - tending not to dissolve in water (water-hating).
Ex. attractions btw nonpolar molecules
example of hydrophobic molecules Right Ans - nonpolar covalent
molecules like hydrocarbons like hexane or fatty acids, cholesterol
amphipatic Right Ans - molecule that contains both hydrophobic and
hydrophilic regions
hydrogen bonds form between Right Ans - an electronegative atom and H
Hydrogen bonds between ____ and ______ and between ____ and _____ base pairs
stabilize the double helix. Right Ans - adenine and thymine; guanine and
cytosine
Acid Right Ans - Molecule that behaves as a proton donor
Base Right Ans - Molecule that behaves as a proton acceptor
Acid strength is the tendency of an acid to Right Ans - dissociate to a
hydrogen ion and its conjugate base
Acid strength characterized by Right Ans - acid dissociation constant (Ka)
,acid equation Right Ans - HA (acid) +H2) (base) --> --< H3O+ (conj acid to
H2o) + A- (conj base to HA)
Ka formula Right Ans - [H+][A-]/[HA]
greater the Ka the Right Ans - stronger the acid
pH formula Right Ans - pH = -log10[H+]
pKa formula Right Ans - -log10Ka
the smaller the pka Right Ans - the stronger the acid
Henderson-Hasselbach Equation Right Ans - When concentrations of a
weak acid and its conjugate base are equal, the pH of the solution equals the
pKa of the weak acid
Titration Right Ans - Experiment in which measured amounts of base are
added to an acid
Equivalence point for titration Right Ans - Point in an acid-base titration at
which enough base has been added to neutralize the acid
Monoprotic acids Right Ans - release one H+ ion and have a single Ka and
pKa
Diprotic acids Right Ans - release two H+ ions and have two Ka values and
two pKa values
Polyprotic acids Right Ans - release more than two H+ ions
When pH < pKa Right Ans - the weak acid predominates; H+ on, substance
protonated
When pH > pKa, Right Ans - the conjugate base predominates; H+ off,
substance deprotonated
,buffer solutions Right Ans - Tend to resist change in pH when small to
moderate amounts of a strong acid or strong base are added
buffe solutions consist of Right Ans - a weak acid and its conjugat base (ex.
CH3COOH and CH3COONa → Acetic acid and Sodium acetate)
buffers follow what principle Right Ans - Le Chatelier's Principle
how do buffers follow le Chatelier's principle? Right Ans - - If stress is
applied to a system in equilibrium, the equilibrium will shift in the direction
that relieves the stress
- When H+ ion is added to a buffer system, stress is added to the reaction
-To relieve the stress, H+ reacts with A- to maintain equilibrium
pH changes little in the vicinity of the ____________ of a titration curve Right
Ans - inflection point
at the inflection point, Right Ans - half the amount of acid originally present
has been converted to the conjugate base
Buffer solutions can maintain a Right Ans - relatively constant pH value,
which is met at values at or near the pKa of the acid
amino acids include Right Ans - amino groups, carboxyl group, Hydrogen,
and R group bonded to alpha carbon
amino group Right Ans - (—NH2) functional group
carboxyl group Right Ans - -COOH functional group
Two stereoisomers of amino acids are designated as Right Ans - L- and D-
amino acids
strereoisomers Right Ans - Molecules that differ from each other only in
their configuration
With the exception of ______, all amino acids have at least ______ and _______
Right Ans - glycine; one chiral center (the a-carbon) and are chiral
(stereoisomers)
, Vast majority of a-amino acids have the _______ at the a-carbon Right Ans - L
configuration
alanine Right Ans - Ala, A
arginine Right Ans - Arg, R
Asparagine Right Ans - Asn, N
aspartic acid Right Ans - Asp, D
cysteine Right Ans - Cys, C
glutamic acid Right Ans - Glu, E
glutamine Right Ans - Gln, Q
Glycine Right Ans - Gly, G
histidine Right Ans - His, H
Isoleucine Right Ans - Ile, I
leucine Right Ans - Leu, L
lysine Right Ans - Lys, K
methionine Right Ans - Met, M
phenylalanine Right Ans - Phe, F
proline Right Ans - Pro, P
Serine Right Ans - Ser, S
Threonine Right Ans - Thr, T
tryptophan Right Ans - Trp, W
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