General Biochemistry USF Exam 1
Questions with Correct Answers
hydrogen bond - ANSWER-Positive end of one dipole is a hydrogen atom bonded to
a highly electronegative atom (hydrogen-bond donor)
Negative end of the other dipole is an atom with a lone pair of electrons (hydrogen-
bond acceptor)
Hydrogen bonds are strongest when the bonded molecules allow for linear bonding
patterns.
importance of hydrogen bonds - ANSWER-Source of unique properties of water
• Structure and function of proteins
• Structure and function of DNA
• Structure and function of polysaccharides
• Binding of substrates to enzymes
• Binding of hormones to receptors
• Matching of mRNA and tRNA
Hydrophobic effect - ANSWER-Nonpolar portions of the amphipathic molecule
aggregate so that fewer water molecules are ordered and entropy increases.
With high enough concentration of amphipathic molecules, complete aggregation
into micelles is possible.
micelles - ANSWER-lipid molecules orient with polar (hydrophilic) head toward water
and nonpolar (hydrophobic) tails away from water
entropy increases
Acid - ANSWER-Molecule that behaves as a proton donor
Base - ANSWER-Molecule that behaves as a proton acceptor
acid-base reaction - ANSWER-
acid dissociation constant - ANSWER-Ka = [H3O+][A-]/[HA]
pKa = -log(Ka)
equilibrium constant - ANSWER-K=[H][OH-]/[H2O]
[H][OH-]= 1*10^-14M^2
in pure water - ANSWER-[H]=[OH-]=10^-7M
pH - ANSWER-pH=-log[H+]
-log[H]-log[OH-]=14
pH+pOH=14
, Henderson-Hasselbalch equation - ANSWER-pH = pKa + log [A-]/[HA] (base/acid)
Buffers - ANSWER-mixtures(weak acids and anions) that can react with acids or
bases to keep the pH within a particular range
To relieve the stress, H+ reacts with A- to maintain equilibrium
buffer capacity - ANSWER-the amount of acid or base a buffer solution can absorb
without a significant change in pH
Amino acid - ANSWER-
nonpolar(hydrophobic) - ANSWER-Methionine
Leucine
Tryptophan
Proline
Phenylanaline
Alanine
Isoleucine
Valine
Glycine
Polar Uncharged - ANSWER-Theronine
Serine
Cysteine
Asparagine
Tyrosine
Glutamine
Acidic - ANSWER-Aspartic acid
Glutamic acid
Basic - ANSWER-Histidine
Lysine
Arginine
isoelectric point (pI) - ANSWER-pl=(pK1+pK2)/2
Separation by Charge: Ion Exchange - ANSWER-Protein mixture is added to column
containing cation exchangers. Proteins move through the column at rates
determined by their net charge at the pH being used. With cation exchangers,
proteins with a more negative net charge move faster and elute earlier.
Separation by Size: Size Exclusion - ANSWER-Protein mixture is added to column
containing cross-linked polymer. Protein molecules separate by size; larger
molecules pass more freely, appearing in the earlier fractions.
Separation by Binding: Affinity - ANSWER-solution of ligand is added to column,
protein mixture is added to column containing a polymer-bound ligand specific for
protein of interest
Questions with Correct Answers
hydrogen bond - ANSWER-Positive end of one dipole is a hydrogen atom bonded to
a highly electronegative atom (hydrogen-bond donor)
Negative end of the other dipole is an atom with a lone pair of electrons (hydrogen-
bond acceptor)
Hydrogen bonds are strongest when the bonded molecules allow for linear bonding
patterns.
importance of hydrogen bonds - ANSWER-Source of unique properties of water
• Structure and function of proteins
• Structure and function of DNA
• Structure and function of polysaccharides
• Binding of substrates to enzymes
• Binding of hormones to receptors
• Matching of mRNA and tRNA
Hydrophobic effect - ANSWER-Nonpolar portions of the amphipathic molecule
aggregate so that fewer water molecules are ordered and entropy increases.
With high enough concentration of amphipathic molecules, complete aggregation
into micelles is possible.
micelles - ANSWER-lipid molecules orient with polar (hydrophilic) head toward water
and nonpolar (hydrophobic) tails away from water
entropy increases
Acid - ANSWER-Molecule that behaves as a proton donor
Base - ANSWER-Molecule that behaves as a proton acceptor
acid-base reaction - ANSWER-
acid dissociation constant - ANSWER-Ka = [H3O+][A-]/[HA]
pKa = -log(Ka)
equilibrium constant - ANSWER-K=[H][OH-]/[H2O]
[H][OH-]= 1*10^-14M^2
in pure water - ANSWER-[H]=[OH-]=10^-7M
pH - ANSWER-pH=-log[H+]
-log[H]-log[OH-]=14
pH+pOH=14
, Henderson-Hasselbalch equation - ANSWER-pH = pKa + log [A-]/[HA] (base/acid)
Buffers - ANSWER-mixtures(weak acids and anions) that can react with acids or
bases to keep the pH within a particular range
To relieve the stress, H+ reacts with A- to maintain equilibrium
buffer capacity - ANSWER-the amount of acid or base a buffer solution can absorb
without a significant change in pH
Amino acid - ANSWER-
nonpolar(hydrophobic) - ANSWER-Methionine
Leucine
Tryptophan
Proline
Phenylanaline
Alanine
Isoleucine
Valine
Glycine
Polar Uncharged - ANSWER-Theronine
Serine
Cysteine
Asparagine
Tyrosine
Glutamine
Acidic - ANSWER-Aspartic acid
Glutamic acid
Basic - ANSWER-Histidine
Lysine
Arginine
isoelectric point (pI) - ANSWER-pl=(pK1+pK2)/2
Separation by Charge: Ion Exchange - ANSWER-Protein mixture is added to column
containing cation exchangers. Proteins move through the column at rates
determined by their net charge at the pH being used. With cation exchangers,
proteins with a more negative net charge move faster and elute earlier.
Separation by Size: Size Exclusion - ANSWER-Protein mixture is added to column
containing cross-linked polymer. Protein molecules separate by size; larger
molecules pass more freely, appearing in the earlier fractions.
Separation by Binding: Affinity - ANSWER-solution of ligand is added to column,
protein mixture is added to column containing a polymer-bound ligand specific for
protein of interest
