Biochem Final - Exam Questions
Glycolysis uses ___
1 glucose 2 ATP 2 NAD+
Which of the following amino acids have polar, uncharged R groups?
1. Lysine and cysteine 2. Serine and asparagine 3. Methionine and glutamine 4. Tryptophan and tyrosine
In the following LDH reaction what is 1 and what is 2? (2 is on top)
1. NADH 2. NAD+
Formation of open complex involves unwinding of DNA, how many bases are unwound in that complex?
14
Eukaryotic ribosomes have all of the following RNAs except:
16s
Epimers
2 sugars that differ in stereochemistry at only one carbon
Alpha helix with the length of 40 A will have __ amino acids
26
DNA polymerase have all of the following enzymatic activities EXCEPT:
3'-5' Endonuclease
EXCEPT:
3'-5' endonuclease activity
When glucose completely oxidizes to CO2 through glycolysis and then CAC then the direct and indirect ATP yield is ___
32 ATP
How many ATPs are generated during the pay off phase of glycolysis?
4
In ice, water molecule makes hydrogen bonds with ____ total surrounding molecules
4
DNA sequence is read from ..
5' to 3'
DNA polymerases enzymatic activities are:
5'-3' exonuclease 5'-3' polymerase 3'-5' exonuclease
Which of the following process is used in the production of foods like yogurt and soy sauce?
Fermentation & Anaerobic glycolysis
Stop codons are also called..
Nonsense codons
Compounds that inhibit key steps in glycolysis can kill cancer cells by
limiting energy production
What will be the net charge on the following peptide in pH 3 solution? Ala-Ser-Asp-Pro-Lys-Val-Glu-Leu-His-Gly
+2
Which of the following forms of Lysine will exist at pH 5?
+H3N - CH - COO- (NH3+ at the end of chain)
TTGACA sequence after trp..... before sequence
-35
Determine the fraction of Vmax that would be obtained at substrate concentration that is equal to 3.75 km.
0.8
Eukaryotic translation initiation is different from prokaryotes by:
1. Eukaryotic initiation requires more initiation factors. 2. Eukaryotic translational initiation is mechanistically different. 3. There is a step that circularizes mRNA during eukaryotic intiation.
White type of enzymes facilitate lateral diffusion of lipids in a bilayer?
1. Flippase 2. Floppase 3. Scramblase 4. None of the above Answer: ?
Which of the following is true for membranes?
1. Two leaflets of lipid bilayer have different lipid compositions. 2. Ratio of lipid to protein does not change from one membrane to the other. 3. Membranes retain metabolites and ions within the cell.
Which of the following is not a covalent bond?
1. peptide bond 2. Disulfide bond 3. Glycosidic bond 4. Hydrogen Bond
If a pKa of a carboxylic group A is 7 and for carboxylic group B is 2, then group A is ____ times less acidic than group B.
100,000
If a velocity of a reaction (vo) is 30 microMS-1, K2 is 800, s is 0.04 mM and Et is 50 nM. Calculate Km for substrate S.
13
Which fatty acid has the highest melting temperature?
20:0
If carbon 1 is the carbonyl group of an aldohexose, which carbon determines if the sugar is regarded as a D or L stereoisomer?
5
Calculate the pH of a solution that contains a molar ratio of conjugate base to acid (pKa = 4.76) of 5:1 and 1:10
5.46 and 3.76
If there are 50 purines in a DNA molecule, how many pyrimidines will be present in the same molecule?
50
If an uncatalyzed reaction occurs at a rate of 5x10^2 and if an enzyme accelerates this reaction 500 times then the rate of the reaction will be?
500x500 = 250,000 = 2.5x10^5
Eukaryotic ribosomes have which RNAs:
5s 28s 5.8s
If the best buffering range for a buffer is ph 6 to ph 8 then what would be the pKa for this buffer?
7
What will be the pH of 0.0000001 M NaOH solution?
7
An activator is..
A positive heterotropic effector
During rho-factor independent termination,
A's in DNA spontaneously attaches to T's in DNA and weakens RNA-DNA hybrid
During prokaryotic translation elongation, the incoming aminoacyl tRNA binds to ____ site of the 70s initiation complex
A.
All of the following are coenzymes for pyruvate dehydrogenase complex EXCEPT:
AMP
The currency of energy in the cell is in the form of
ATP and NAD(P)H
What are the products of pyruvate decarboxylase reaction during ethanol fermentation?
Acetaldehyde and CO2
Cellular respiration involves all of these stages:
Acetyl CoA production Acetyl CoA oxidation Electron transfer and oxidative phosphorylation
EXCEPTT:
Acetyl coA reduction
Which enzyme catalyzes a conversion of a tertiary alcohol to a secondary alcohol in a CAC?
Aconitase
Which of the following CAC reaction is reversible?
Aconitase
Phosphorylation of glucose does:
Activates glucose Traps glucose inside the cell Lowers intracellular glucose concentration
EXCEPT :
Addition of large peptide to the protein.
Which step utilizes CoASH in CAC?
Alpha Ketoglutarate dehydrogenase
tRNA molecules have amino acid attached at 3' end via ____
Amino acyl ester bond
In an alpha helix, the R groups on the amino acid residues:
Are found on the outside of the helix spiral
Beta sheets are either parallel or anti-parallel, because of ___.
Arrangement of N and C terminal
Ionic Bonds & forces
Attraction between 2 opposite charges - 20 kj/mol individually weak, together strong
Phosphofructokinase-1 is regulated by:
Both ATP and Fructose-2,6-biphosphate
DNA denaturation does NOT cause
Breakage of covalent bonds
Protein X has a bound small molecule compound A. Compound A has unique absorbance at 450 nm. For this reason, you wish to separate a population of protein that has bound compound A from free compound A in solution. This will help in characterizing protein by using 450 nm as a unique wavelength. How would you do that?
By size exclusion chromatography
If an anticodon 1st position is G then it can make H bond interaction with this base in the third position of the codon
C, A
What is an ampholyte and zwitterion?
Can both act as an acid or a base Has R groups with one - charge and one + charge
Posttranslational modifications of protein all of the following:
Carbohydrate attachment Removing sequence to activate enzyme Removal of signal sequences
Nucleotides play functions other than being a part of DNA/RNA, which of the following functions CANT be performed by nucleotides?
Catalysts
Eukaryotes are largely
Chemoheterotrophs
What is the product of the rate limiting step of the CAC?
Citrate
The following figure shows attachment of aminoacyl ACP to a sugar of the adenin base during a catalysis by aminoacyl tRNA synthetases. Which class is this for?
Class 2
Allosteric modulator does everything that is listed below except:
Competes with a substrate for the same binding site.
Which of the following is the first committed step of glycolysis?
Conversion of fructose-6-P to fructose-1,6-biphosphate
Which step of the citric acid cycle is a hydration step?
Conversion of fumarate to malate
Inosine can be made by ___ of ___.
Deamination, adenosine
Acetylation modifies enzymatic activity by
Decreasing and Increasing it
Below is a structure of L-Fucose, this is a type of _____
Deoxy sugar (oxygen missing on the 6 carbon)
Which of the following component is NOT required for prokaryotic translation initiation?
EF-G
2-phosphoglycerate is converted to phosphoenolpyruvate by
Enolase
Flippases
Enzyme that catalyzes lipid movement in a bilayered membrane. Moves from outer to cytosolic leaflet
Eukaryotic translation initiation is different from prokaryotic by the following EXCEPT:
Eukaryotic initiation requires both ribosomal subunits.
Exam 2
Exam 2
Exam 3
Exam 3
What form is this structure of alanine?
Fully protonated
All of the following is true about fermentation-
Generation of ATP without consuming O or NAD+ No net change in oxidation state of sugars Regenerates NAD+ for further glycolysis Reduction of pyruvate to another product
Glucose molecules are cleaved from glycogen and starch by glycogen phosphorylase yielding ___
Glucose 1-phosphate
Maximum gene expression for lac operon will occur by
Glucose low, cAMP high, Lactose present
What amino acids DO take part of acid base catalysis?
Glutamate Cystine Lysine
Amino acid below is a derivative of a common amino acid ____, which is ____ amino acid.
Glutamate & uncharged
Of the 20 standard amino acids, only _________ is not chiral. The reason is that its side chain _______.
Glycine; is a hydrogen atom.
Succinate dehydrogenase reaction
Has a covalently linked FAD Not regulated Does not produce NADH
What is NOT true about transition state?
Has a defined chemical structure.
A glycosidic bond is the result of a..
Hemiketal or hemi acetal reacting with an alcohol.
What determines a high Tm in a DNA sequence?
High amounts of G and C
How to determine if a structure of a sugar is D or L?
If the OH is on the right (D) or the left (L) of the chiral center farthest from the carbonyl carbon (C=O)
DNA proofreading activity is all of the following:
Increases fidelity of replicaiton Removes mispaired nucleotide Double checks each nucleotide after adding it
Lac operon is an example of ___
Induction
EXCCEPT:
Is also called aerobic glycolysis
DNA POL 1 functions:
Is not ideal for DNA replication Polymerization rate is slower than the fork movement Main function is clean up in various processes
Which of the following enzyme catalyzes oxidative decarboxylation step in CAC?
Isocitrate dehydrogenase & Alpha ketoglutarate dehydrogenase
DNA POL 1 is not a primary replication polymerase because:
It has low processivity and polymerization rate.
When phosphatidylserine is present outside of the cell,
It is a marker for cell destruction.
Which of the following is NOT true about the nature of the genetic code?
It is generally overlapping
Lactate produced by lactic acid fermentation gets transported to ___ for gluconeogenesis.
Liver
Van Der Waals forces are ______ in strength compared to H bonds.
Lower
Which of the following is NOT true for membranes?
Membranes are asymmetric
What type of catalytic mechanism is used by enzymes to participate in oxidation reactions?
Metal ion catalysis
These are the only two amino acids with single codons.
Methionine and tryptophan
RNA polymerases have which of the following metal ion to aid in the catalytic reaction?
Mg2+
Enzymes involved in the production of ethanol in yeast use all of the following cofactors EXCEPT:
Mn2+
Multienzyme complexes provide all of the following advantages EXCEPT:
Mostly involved in oxidation/reduction reactions
Protein has a characteristic 280 nm absorbance because of ___
Mostly tryptophan and tyrosine
Tautomerization
Moves a hydrogen changing enol to keto form
Scramblase
Moves lipieds in either direction toward equilibrium
The messelson-Stahl experiment used a heavy isotope of which atom?
N
Which of the following is not a substarte for the reaction catalyzed by glyceraldehyde 3-phosphate dehydrogenase?
NADH
These molecules are general inhibitors of CAC
NADH and ATP
Which of the following organism require presence of oxygen for growth?
Obligate aerobe
Anaplerotic reactions fill up which of these intermediates in CAC?
Oxaloacetate and Malate
Which of the following enzymes is NOT a part of gluconeogenesis path way?
PEP carboxylase
Hydrophobic interactions most likely occur between which of the following R groups in amino acids?
Phenylalanine and tryptophan
Formation of 3-phosphoglycerate from 1,3-biphosphoglycerate is catalyzed by
Phosphoglycerate kinase
The lifetime of H bond in water molecules is in
Picoseconds (ps)
What IS true about transition state?
Present in enzyme catalyzed reactions Very short lived Is complementary to the enzyme
Phosphoylation of glucose does all of the following EXCEPT:
Promotes glucose transport from inside to outside of a cell
If three proteins X, Y, and Z with MW of 10, 15, 70 kDa are being separated by gel filtration chromatography then which of the following is correct?
Protein Z with MW will elute first (because it's a column)
TuC arm of tRNA contains which of the following uncommon nucleoside?
Pseudouridine
Anaplerotic reactions are catalyzed by all of the following enzymes EXCEPT:
Pyruvate carboxykinase
Ethanol fermentation in yeast involves these 2 enzymes.
Pyruvate decarboxylase & alcohol dehydrogenase
During lactate dehydrogenase catalyzed reaction
Pyruvate is reduce to give lactate
Which of the following steps of glycolysis neither use nor make ATP:
Reaction catalyzed by phosphoglycerate mutase
Fermentation involves all of the following EXCEPT:
Reduction of pyruvate to acetyl-CoA
What CAN nucleotides do?
Regulatory molecules Coenzymes Energy source
What is the bond between the following disaccharide:
Ribose-beta-1,4-glucose
The initiating 5' AUG codon of mRNA is guided to its correct position by the ___ sequence.
Shine delgarno
What is the shape of the curve of initial velocity vs substrate concentration for allosteric enzymes?
Sigmoidal
Which step of glycolysis called phosphohexose isomerization?
Step 2
DNA denaturation DOES cause:
Strand separation Increase in UV absorbance Breakage of H bonds
All of the following reactions produce NADH in the CAC EXCEPT:
Succinate dehydrogenase
All of the following steps of CAC are regulated EXCEPT:
Succinate dehydrogenase reaction
Which CAC enzyme has a covalently linked FAD, which is very unusual.
Succinate dehydrogenase.
Substrate level phosphorylation is catalyzed by ___ enzyme in CAC
Succinyl CoA Synthetase
Which of the following toxin blocks A site on the ribosome?
Tetracyclines
A glycosidic bond is the covalent linkage between
The anomeric carbon of a saccharide and an alcohol
Which of the following is NOT true for integral membrane proteins?
They are removed by disrupting ionic interactions either with high salt/pH change
Which of the following is true for integral membrane proteins
They can span both leaflets. Purified int. membrane proteins are generally associated with some lipids Integral proteins can be monotopic or polytopic
How to draw a fisher projection from a howarth projection
Top goes on the right
Mutase is an enzyme that __
Transfers a group from one carbon to another
Enzyme complementary to the ____ would be the best enzyme.
Transition state
What kind of enzyme is EF-G?
Translocase
Hydropathy plots can predict..
Transmembrane domains
Which of the following amino acid does NOT participate in acid base catalysis?
Tryptophan
Non-Covalent bonds and their forces
Van der Waals - electrical interaction - 0.4-4.0 kj/mol Hydrogen bonds - shared protons - 12-30 kj/mol
Which is NOT true about DNA POL 1?
With all its domains in tact, its also called Klenow fragment
For an acid AH, pH = pK when:
[A] = [HA]
Which of the following functional groups containing compounds participate in H-bond formation?
alcohol, ketone, aldehyde (all of the above)
Humans do not have an enzyme to synthesize this essential fatty acid
alpha-linolenic acd
Example of substrate level phosphorylation in glycolysis:
both A and B (kinase options) a. pyruvate kinase reaction b. phosphoglycerate kinase reaction
Amphitrophic proteins are __
conditionally attached to membranes and can be reversibly removed.
Conversion of Glucose-6-P to Fructose-6-P is ___ type of reaction
isomerization
Floppase
moves from cytosolic to outer leaflet
During strenuous exercise lactate builds up in
muscle
What is this structure?
n-Tetracosanoic acid
Which of the folllowing are important for human nutrition?
omega 3
Replication begins at the ___
origin
Ramachandran plot is base on..
phi and psi angles
Cation exchangers are
polymers with bound negatively charged groups
Which ribosomal component catalyzes peptide bond formation?
r-RNA
Rhodopsin is a membrane protein that acts as a..
receptor
Proteins can be eluted form ion-exchange column by using gradients of
salt & pH
The only form of DNA that is left-handed in nature is
the Z form
The isoelectric point is
the pH at which a substance has no net charge
They do use:
TPP Mg2+ Zn2+
Role of mRNA is to
code for protein