Bio Chemistry Interview Questions
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What is a plasmalogen? What do plasmalogens do?

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What is the role of PAPS?

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what is Alzheimer's disease?what are its symptoms?

1 3108

Compare and contrast feedback inhibition and enzyme repression?


The peptide bond in proteins is a) nonpolar, and fixed in a trans conformation. b) nonpolar, but rotates to three preferred dihedral angles. c) planar, and usually found in a trans conformation. d) planar, but rotates to three preferred dihedral angles.

1 1669

If the enthalpy change for a reaction is zero, DG? is equal to: a) DH? b) lnKeq c) TDS? d) -TDS?

1 1871

The nucleophile in the first stage of the serine protease mechanism is a) H2O b) the carboxyl of Asp 102 c) the hydroxyl of Ser 195 d) the imidazole of His 57


The elution volume of an enzyme on a gel filtration column can be predicted from a) its enzyme activity b) its protein absorbance at 280 nm c) subunit composition and monomer molecular mass(es) d) Choices a) and b) are both correct.


DNA binding by proteins with the helix-turn-helix (HTH) motif does not involve a) altered stacking of the DNA at the center of symmetry. b) hydrogen bonds, salt bridges, and van der Waals contacts. c) interactions with base pairs in the major groove of DNA. d) interactions with the sugar-phosphate backbone of DNA.


The two exonuclease activities of DNA polymerase I a) are coupled during the formation of "gapped DNA". b) degrade DNA in a 5' --> 3' direction. c) degrade DNA in a 3' --> 5' direction. d) occur at two different active sites.

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A principal difference between prokaryotic and eukaryotic DNA replication is a) completely different proteins/enzymes in eukaryotes b) multiple origins in eukaryotes c) no requirement for topoisomerase activity in prokaryotes d) the absence of a nucleus in prokaryotes

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When s subunit dissociates from an initiated RNA polymerase, a) it can bind a core enzyme to reform holoenzyme. b) it hydrolyzes ATP until rebound by core enzyme. c) it leaves behind an elongating species complexed with Rho factor. d) it remains bound to the promoter consensus sequence.

1 1751

The junction between the two helical portions of tRNA is stabilized by many non-standard base-base interactions between residues in the a) anticodon and CCA ends. b) helical stems of the D and Anticodon stems. c) loops of the Anticodon and Acceptor stem. d) loops of the TYC and D arms.

1 1389

On the ribosome, mRNA binds ____; the peptidyl transferase reaction occurs ____. a) to the large subunit; on the small subunit. b) to the small subunit; on the large subunit. c) between the subunits; on the large subunit. d) between the subunits; on the small subunit.

2 2627

According to the fluid mosaic model of cell membranes, which type of molecule spans the membrane from its inner to outer surface? a) cholesterol b) phospholipid c) protein d) triacylglycerol

PH.D Interview,

1 2642

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Un-Answered Questions { Bio Chemistry }

Which vitamins participate, in coenzyme form, in reactions of the tricarboxylic acid cycle?


Why are free cysteines treated with iodoacetate prior to protein sequencing?


Why is the t-butyloxycarbonyl protecting group such a good choice for amino acid synthesis?


What factors are involved in determining the electrophoretic mobility of a molecule?


The nucleophile in the first stage of the serine protease mechanism is a) H2O b) the carboxyl of Asp 102 c) the hydroxyl of Ser 195 d) the imidazole of His 57


"Tell me about a job that you found particularly satisfying. What did you like about it?


why we use 96 well plate in ELISA plate reader?


How does a random coil differ from an irregularly structured region?


what is your aspiration in profession/ career?


What is the structural formula of molybdenum blue?


What are hydrophobicity scales, and how are they used?


i have done M.SC. in biochemistry from india. as i have experience of pharmaceuticals in quality assurance department of 4 i come to know that my degree is valid in uk.i got my comparision letter of degree from uknaric. but i m confuse that what is the next step to do for getiing job in lab? am i eligible to get directly job or as trainee than job ? or to register in ibms or what? pls tell me


bane the by products when crude oil is refined by distillation


I understand that urine can act as a reagent to break disulfide bonds? I am particularly interested in bonds between cysteines. and or any other amino acids.


I have given the protocol for the cyclodextrin glygosyl transferase assay: One ml of appropriately diluted enzyme sample was incubated at 60 °C for 15 min with 5 ml of 1% (w/v) gelatinized soluble starch in 50 mM, 7.0-pH Tris–HCl buffer. Reaction was terminated by boiling the reaction mixture for 3 min and reaction volume was made to 10 ml with distilled water. Two ml of above reaction mixture was withdrawn and mixed with 3 ml of Tris–HCl buffer, 5 ml of 125 mM Na2CO3, and 0.5 ml of phenolphthalein (25 mg phenolphthalein/100 ml absolute alcohol). Absorbance was measured at 550 nm. The percent decrease of sample was calculated with respect to control containing 5 ml of buffer, 5 ml of sodium carbonate and 0.5 ml of phenolphthalein. where Acontrol = absorbance of control and Atest = absorbance of sample. The amount of β-cyclodextrin (β-CD) produced was estimated from the standard graph of 0–500 μg/ml β-CD concentration against % decrease in absorbance. One unit of CGTase was defined as the amount of enzyme required to produce 1 μm of β-CD/min. Please can you suggest me the formula for the defination given in the last line