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Biochemistry Final Review
review of material for biochem final
97
Chemistry
Undergraduate 4
12/09/2009

Additional Chemistry Flashcards

 


 

Cards

Term
[image]
Definition
Valine
Term
[image]
Definition
Aspartate
Term
[image]
Definition
Arginine
Term
[image]
Definition
Cystine
Term
[image]
Definition
Glutamate
Term
[image]
Definition
Histidine
Term
[image]
Definition
Lysine
Term
[image]
Definition
Phenylalanine
Term
[image]
Definition
Serine
Term
[image]
Definition
Threonine
Term

Which amino acid is non-polar?
A) aspartate

B) arginine

C) threonine

D) lysine

E) valine

Definition
E) valine
Term
In the following peptide (angiotensin I), which amino acid is the carboxyl terminus?
Asn-Arg-Val-Tyr-Val-His-Pro-Phe-His-Leu
Definition
A) Leu
Term
Why is the peptide bond planar?
Definition
B) It has partial double bond character, due to resonance.
Term
An acid with a pK of 5.0 is in a solution with a pH of 7.0. What is the ratio of the deprotonated to protonated form of the acid, [A-]/[HA]?
Definition
A) 100:1
Term
10. What is the net charge on glycine at pH 12?
Definition
A) -1
Term
The structure of collagen is mostly:
Definition
C) collagen helix
Term
A motif is:
Definition
D) a stable arrangement of several secondary structure elements
Term

You have a sample of a large protein (molecular weight = 100,000 kD). The protein is contaminated with several other proteins (molecular weights = 25,000 - 50,000 kD). Which of the methods below would separate the large protein from the small proteins?
A) Add 8 M urea and mercaptoethanol

B) SDS polyacrylamide gel electrophoresis
C) dialysis D) heat to 75oC E) none of these

Definition
B) SDS polyacrylamide gel electrophoresis
Term

Which of the following is a non-covalent interaction that stabilizes proteins in their biologically active folded state?
A) peptide bonds B) hydrogen bonds

C) acyl enzyme D) disulfide bonds
E) none of these

Definition
B) hydrogen bonds
Term
Quaternary structure refers to:
Definition
B) the spatial arrangements of subunits and the nature of their interactions
Term

17. Which can form an ion pair with glutamate?

A) arginine B) valine C) cysteine D) serine

E) none of these

Definition
A) arginine
Term

Which is most likely to occur in the interior of a protein folded into its native structure?

A) arginine B) valine C) cysteine D) serine

E) none of these

Definition
B) valine
Term

Which can form disulfide bonds?

A) arginine B) valine C) cysteine D) serine

E) none of these

Definition
C) cysteine
Term
If amino acid sequence determines 3D structure, how can divergent amino acid sequences produce structurally and functionally similar proteins? Identify the incorrect statement:
A) Conservative substitutions make sequences diverge without altering 3D structure and function
B) Only a few key parts of the structure are essential for function
C) Only a few key parts of the sequence are essential for determining the 3D structure
D) Unfolded proteins are as active as folded proteins
E) all statements are correct
Definition
D) Unfolded proteins are as active as folded proteins
Term
Most unfolded proteins spontaneously refold to the biologically active state because:
Definition
A) the free energy of the folded state is lower than the free energy of the unfolded state
Term
A non-polypeptide unit such as heme, bound to a protein, is called:
Definition
B. a prosthetic group
Term
Comparing hemoglobin and myoglobin, which properties are similar?
Definition
A. oxygen binding site
Term
The free energy of activation is:
Definition
A) the energy difference between the substrate and the transition state.
Term
The value of KM is equal to the:
Definition
B) substrate concentration when the reaction rate is half its maximal value.
Term
When substrate concentration is many times greater than KM, the reaction velocity is nearly equal to:
Definition
C) Vmax
Term
Which of the following is NOT a property of a typical enzyme active site?
A) a small part of the total enzyme structure.
B) a cleft or crevice.
C) formed from amino acids at widely separated regions of the sequence.
D) a mirror image of the inactive site, which is on the opposite side of the enzyme.
E) none of these
Definition
D) a mirror image of the inactive site, which is on the opposite side of the enzyme.
Term
What does Vmax indicate?
Definition
C) the amount of product per unit time produced by an enzyme with all active sites have substrate bound
Term
An enzyme has a maximum velocity of 10-5 M/sec at a total enzyme concentration of 10-8 M. What is the turnover number for this enzyme?
Definition
B) 1000
Term
An uncompetitive inhibitor:
Definition
D) binds to the enzyme-substrate complex
Term
Which amino acids in chymotrypsin are found in the active site and are participants in substrate cleavage?
Definition
D) His, Ser, Asp
Term
Which of the following is NOT a mechanism by which enzymes increase reaction rates?
A) causing the temperature of the substrate to increase
B) covalent intermediate
C) using substrate-binding energy
D) general acid-base catalysis
E) none of these
Definition
A) causing the temperature of the substrate to increase
Term
Which of the following contributes to the catalytic mechanism of chymotrypsin?
A) A zinc ion polarizes a water molecule
B) The oxyanion hole distorts the peptide carbonyl out of plane and stabilizes the tetrahedral intermediate
C) A magnesium ion polarizes a water molecule and positions it to attack the substrate
D) The enzyme undergoes a conformational change from the R state to the T state
E) none of these
Definition
B) The oxyanion hole distorts the peptide carbonyl out of plane and stabilizes the tetrahedral intermediate
Term
What is the function of the catalytic triad of chymotrypsin?
Definition
A) Converts the active site Ser into a powerful nucleophile
Term
In which regulatory mechanism is the final product of a pathway an inhibitor of the activity of the first step?
Definition
B) feedback inhibition
Term
When a molecule of O2 binds to one heme in deoxyhemoglobin
Definition
D) it causes conformational changes which affect the other hemes
Term
Many allosteric enzymes have two types of subunits, termed:
Definition
C) catalytic and regulatory
Term
The catalytic rate of an allosteric enzyme in the R form is _________ than the catalytic rate in the T form.
Definition
C) higher
Term
The effects of substrate binding to one subunit of an allosteric enzyme on substrate binding to another subunit are referred to as _______ effects.
Definition
B) homotropic
Term
When an enzyme catalyzes a reaction involving more than one substrate, a common reaction type is known as:
Definition
C) double-displacement
Term
Penicillin inhibits bacterial cell wall synthesis by:
Definition
D) covalent modification of active site serine in glycopeptide transpeptidase
Term
[image]
Definition

On the graph below, curve B represents the rate vs. substrate graph for ATCase in the absence of regulatory molecules. Which curve best represents the kinetics in the presence of the feedback inhibitor CTP?

 

C

Term
How is specificity determined by chymotrypsin?
Definition
B) binding of a large, non-polar substrate side chain into a deep pocket on the enzyme
Term
In the following peptide (angiotensin I), which amino acid is the amino terminus?
Asn-Arg-Val-Tyr-Val-His-Pro-Phe-His-Leu
Definition
Asn
Term
An acid with a pK of 7.0 is in a solution with a pH of 5.0. What is the ratio of the deprotonated to protonated form of the acid, [A-]/[HA]?
Definition
C) 1:100
Term
What is the net charge on glycine at pH 2?
Definition
C) +1
Term

Which of the following is a non-covalent interaction that stabilizes proteins in their biologically active folded state?
A) peptide bonds B) acyl enzyme

C) van der Waals interactions

D) disulfide bonds E) none of these

Definition
C) van der Waals interactions
Term

Which can form an ion pair with aspartate?

A) serine B) histidine C) leucine

D) cysteine E) none of these

Definition
B) histidine
Term

Which is most likely to occur in the interior of a protein folded into its native structure?

A) serine B) histidine C) leucine

D) cysteine E) none of these

Definition
C) leucine
Term

Which can form disulfide bonds?

A) serine B) histidine C) leucine

D) cysteine E) none of these

Definition
D) cysteine
Term
[image]
Definition
Adenine
Term
[image]
Definition
Guanine
Term
[image]
Definition
Cytosine
Term
[image]
Definition
Found in RNA but not DNA
Term
Structural similarities between DNA and RNA include:
Definition
D) linked by phosphodiester bonds in sugar-phosphate backbone
Term
Similarities between replication by DNA polymerase and transcription by RNA polymerase:
Definition
A) polymerize 5' to 3'
Term
Which is the least abundant RNA molecule?
Definition
A) mRNA
Term
Which of the following is found in tRNA?
Definition
B) a sequence complementary to mRNA codons
Term
Which of the following is true of the genetic code?
Definition
C) 3-base codons
Term
What DNA sequence is complementary to 5'GAGCATGTTGGCCT 3'?
Definition
B) 5'AGGCCAACATGCTC3'
Term
Which is a protein-RNA complex?
Definition
C) ribosome
Term
Mirror image molecules are called:
Definition
B) enantiamers
Term
An aldehyde and alcohol can react to form a:
Definition
C) hemiacetal
Term
[image]
Definition

Identify a non-reducing end of the polysaccharide below:

 

(B)

Term
[image]
Definition

What is the relationship between these two molecules?

 

(enantiomers)

Term
[image]
Definition
Ketoses
Term
Which amino acids are commonly linked to sugars in glycoproteins?
Definition
B) serine, threonine, and asparagine
Term
Which of the following is a property of membranes?
Definition
Fluid Structures
Term
Which of the following is NOT a function of membranes:
Definition
gene transcription
Term
Which of the following fatty acids has the most double bonds?
A) 18:0 B) 16:2
 C) 16:1 D) 20:1
E) All of the above have the same number of double bonds
Definition
B) 16:2
Term

Which has the highest temperature of transition from ordered to fluid state?

A) 18:0 B) 16:2 C) 16:1 D) 20:1 E) All of the above have the same transition temperature

Definition
A) 18:0
Term
Storage form of fatty acids:
Definition
D) triacylglycerols
Term
Unique functional properties of a particular membrane usually are properties of:
Definition
C) specific membrane proteins
Term
A common structure found in membrane spanning proteins is:
Definition
A) α helices of nonpolar amino acids that pass through the membrane
Term
[image]
Definition

Which lipid is phosphatidyl choline?

 

 

(B)

Term
[image]
Definition

ID integral membrane proteins:

 

 

C) a, b, and c

Term
An example of an active transport protein:
Definition
D) Na+-K+ATPase
Term

Secondary transport involves two substances:

Definition
A) one carried down its concentration gradient and a second carried against its
concentration gradient
Term
The selectivity filter of the K+ channel
Definition
C) coordinates K+ but not Na+
Term
Which of the following is a common second messenger?
Definition
D) cAMP
Term
Identify the correct sequence of events in the activation of protein kinase A by signal transduction via epinephrine:
Definition
A) 1. epinephrine binds to β-adrenergic receptor; 2. G-protein exchanges GDP for GTP;
3. adenylate cyclase is activated; 4. cAMP binds to protein kinase A
Term
What is one mechanism for terminating signal transduction after it has been activated?
Definition
B) G-protein hydrolyzes GTP to GDP
Term
After a receptor tyrosine kinase binds to a hormone on the extracellular side of the membrane, what is typically the next event in the signal transduction pathway?
Definition
A) receptor dimerization and cross-phosphorylation
Term
After a ligand binds to one type of 7TM receptor, the result is to activate
phospholipase C. What step does phospholipase C catalyze?
Definition
C) phosphatidylinositol 4,5-bis-phosphate splits into IP3 and diacylglycerol
Term
How does cAMP activate protein kinase A?
Definition
B) binds to regulatory subunit
Term
In the first stage of metabolism
Definition
C) no useful energy is extracted
Term
[image]
Definition
NAD+
Term

Which is an electron carrier?
A) biotin B) coenzyme A C) NADH D) ATP

E) none of these

Definition
C) NADH
Term
[image]
Definition

Which can transfer phosphate to ADP to form ATP?

 

B)Creatine phosphate

Term
Fats have a higher chemical energy content than carbohydrates because fats are more:
Definition
D) reduced
Term
Why does ATP have a particularly large ΔGo for hydrolysis?
Definition
A)charge repulsion destabilizes the γ-phosphate
Term
How does coupling of reactions permit thermodynamically unfavorable reactions to
go spontaneously?
Definition
B) The sum of the free energy changes of coupled reactions determines the overall spontaneity, so one highly favorable step can overcome some unfavorable steps
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