BIOCHEM ACS STUDY GUIDE
QUESTIONS & ANSWERS
Which Amino Acids will be charged at pH 7? - ANSWERDEHRK: Aspartic Acid (Asp),
Glutamic Acid (Glu), Histidine (His), Arginine (Arg), Lysine (Lys)
Which amino acids will have a negative charge at pH 7? - ANSWERD&E: Aspartic Acid
(Asp) and Glutamic acid (Glu)
Which amino acids will have a positive charge at pH 7? - ANSWERH, R, K: Histidine
(His), Arginine (Arg), Lysine (Lys)
Which of the following sequences are most likely to be in the interior core of a globular
protein?
(A) ITFWLI (B) IKFGVA (C) DKYPGE (D) MPCDNA - ANSWERThe interior is
hydrophilic so sequence: ITFWLI is most likely to be in the interior because there is no
charged amino acids and had the lowest percentage of polar amino acids.
How are beta sheets stabilized in proteins? - ANSWERHydrogen bonding between
peptide backbone groups.
Fibrous Proteins - ANSWERNot water soluble, not flexible in secondary structure, highly
repetitive primary structure, elongated structure; 2 α keratin polypeptides each which
forms an α helix twisting around each other to form a left handed coil.
Globular Proteins - ANSWERWater soluble, flexible in secondary structure, not
necessarily highly repetitive, size and ability to associate into a larger structure varies.
Gel filtration elution - ANSWERLargest elutes first
Competitive inhibitor - ANSWERVmax stays the same different km
Noncompetitive inhibitor - ANSWERSame X axis on reciprocal, same Km different vmax
Uncompetitive inhibitor - ANSWERDifferent Km and vmax
Catalytic efficiency - ANSWERKcat/km higher is more efficient
What are the structural changes in hemoglobin that allows for cooperative binding of
O2? - ANSWERBinding of O2 on one subunit causes a conformational change in
adjacent subunit allowing O2 to bind.
Why does myoglobin not experience cooperative binding of O2? - ANSWERIt's is
monomeric.
, What effect does an enzyme have on ΔG? - ANSWERNone
What effect does an enzyme have on transition state? - ANSWERReaches it quicker
but doesn't stabilize it.
Label the function of H2O, Asp 32, carbonyl, and Asp 215? - ANSWERAsp32=base
because it accepts H+
H2O= nucleophile or acid
Carbonyl= electrophile
Asp 215= acid because it donates H+
What is a transition state inhibitor? How does its affinity for the enzyme compare to that
if the substrate? - ANSWERSimilar structure to substrate (mimics shape of active site.
Binds to active site with greater affinity than substrate.
Would it be advantageous for these potential drugs to covalent lot bond to the enzyme?
Why? - ANSWERNot advantageous because the urea cycle will shut down.
Would it be advantageous for these drugs to be less chemically stable than the
substrate? - ANSWERNo, because of shelf life and time to reach target.
In DNA which bases hydrogen bond? - ANSWERA-T, G-C
In each base pair, how many hydrogen bonds are there? - ANSWERA-T=2 G-C=3
Which base pair would require a higher temp to destroy (met) the hydrogen bonds? -
ANSWERG-C
DNA - ANSWERForms base pairs, double stranded, deoxyribose, A,T,G,C
RNA - ANSWERForms base pairs with hairpin loops, single stranded, ribose, A,U,G,C
Alkaline hydrolysis is the process by which nucleic acids are broken down into
nucleotides using base. Looking at the mechanism of alkaline hydrolysis of RNA below
and your answers to part a, explain why DNA is less susceptible to alkaline hydrolysis. -
ANSWERDNA lacks 2' hydroxyl group.
What's the difference between reducing and non reducing sugars? - ANSWERReducing
sugars have a free anomeric Carbon that in its linear form can reduce and oxidizing
agent
One monosaccharide and 1 disaccharide - ANSWERGlucose and lactose
One non reducing disaccharide. Can a monosaccharide be non reducing? -
ANSWERSucrose. No, all monosaccharides are reducing.
QUESTIONS & ANSWERS
Which Amino Acids will be charged at pH 7? - ANSWERDEHRK: Aspartic Acid (Asp),
Glutamic Acid (Glu), Histidine (His), Arginine (Arg), Lysine (Lys)
Which amino acids will have a negative charge at pH 7? - ANSWERD&E: Aspartic Acid
(Asp) and Glutamic acid (Glu)
Which amino acids will have a positive charge at pH 7? - ANSWERH, R, K: Histidine
(His), Arginine (Arg), Lysine (Lys)
Which of the following sequences are most likely to be in the interior core of a globular
protein?
(A) ITFWLI (B) IKFGVA (C) DKYPGE (D) MPCDNA - ANSWERThe interior is
hydrophilic so sequence: ITFWLI is most likely to be in the interior because there is no
charged amino acids and had the lowest percentage of polar amino acids.
How are beta sheets stabilized in proteins? - ANSWERHydrogen bonding between
peptide backbone groups.
Fibrous Proteins - ANSWERNot water soluble, not flexible in secondary structure, highly
repetitive primary structure, elongated structure; 2 α keratin polypeptides each which
forms an α helix twisting around each other to form a left handed coil.
Globular Proteins - ANSWERWater soluble, flexible in secondary structure, not
necessarily highly repetitive, size and ability to associate into a larger structure varies.
Gel filtration elution - ANSWERLargest elutes first
Competitive inhibitor - ANSWERVmax stays the same different km
Noncompetitive inhibitor - ANSWERSame X axis on reciprocal, same Km different vmax
Uncompetitive inhibitor - ANSWERDifferent Km and vmax
Catalytic efficiency - ANSWERKcat/km higher is more efficient
What are the structural changes in hemoglobin that allows for cooperative binding of
O2? - ANSWERBinding of O2 on one subunit causes a conformational change in
adjacent subunit allowing O2 to bind.
Why does myoglobin not experience cooperative binding of O2? - ANSWERIt's is
monomeric.
, What effect does an enzyme have on ΔG? - ANSWERNone
What effect does an enzyme have on transition state? - ANSWERReaches it quicker
but doesn't stabilize it.
Label the function of H2O, Asp 32, carbonyl, and Asp 215? - ANSWERAsp32=base
because it accepts H+
H2O= nucleophile or acid
Carbonyl= electrophile
Asp 215= acid because it donates H+
What is a transition state inhibitor? How does its affinity for the enzyme compare to that
if the substrate? - ANSWERSimilar structure to substrate (mimics shape of active site.
Binds to active site with greater affinity than substrate.
Would it be advantageous for these potential drugs to covalent lot bond to the enzyme?
Why? - ANSWERNot advantageous because the urea cycle will shut down.
Would it be advantageous for these drugs to be less chemically stable than the
substrate? - ANSWERNo, because of shelf life and time to reach target.
In DNA which bases hydrogen bond? - ANSWERA-T, G-C
In each base pair, how many hydrogen bonds are there? - ANSWERA-T=2 G-C=3
Which base pair would require a higher temp to destroy (met) the hydrogen bonds? -
ANSWERG-C
DNA - ANSWERForms base pairs, double stranded, deoxyribose, A,T,G,C
RNA - ANSWERForms base pairs with hairpin loops, single stranded, ribose, A,U,G,C
Alkaline hydrolysis is the process by which nucleic acids are broken down into
nucleotides using base. Looking at the mechanism of alkaline hydrolysis of RNA below
and your answers to part a, explain why DNA is less susceptible to alkaline hydrolysis. -
ANSWERDNA lacks 2' hydroxyl group.
What's the difference between reducing and non reducing sugars? - ANSWERReducing
sugars have a free anomeric Carbon that in its linear form can reduce and oxidizing
agent
One monosaccharide and 1 disaccharide - ANSWERGlucose and lactose
One non reducing disaccharide. Can a monosaccharide be non reducing? -
ANSWERSucrose. No, all monosaccharides are reducing.
