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 1877If the enthalpy change for a reaction is zero, DG? is equal to: a) DH? b) lnKeq c) TDS? d) -TDS?
1 2051The 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
995The 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.
1993DNA 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.
948The 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.
1 1614A 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
9 30399When 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 1917The 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 1619On 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 2971According 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
1 2943Post New Bio Chemistry Questions
Why are right-handed helices more stable than left-handed helices?
During a heart attack, blood flowing to the heart muscle is interrupted by blockage of a coronary artery. How would you expect the metabolism in the heart to change?
What are the drawbacks of tissue slices technique?
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
mutarotation is observed when phenol and pyridine both are present but phenol or pyridine alone cannot show mutarotation-explain why?
bane the by products when crude oil is refined by distillation
what is your passion?
How are reaction rates dependent upon free energy changes?
Which organ and subcellular site are most important for fatty acid biosynthesis?
Where do hydrophobic and hydrophilic residues usually end up after protein folding?
Two children have a neurological disorder. When cells from the two patients were fused to form heterokaryons containing nuclei from both patients and cultured, the cells displayed normal metabolism. Cells from either patient exhibited abnormal metabolism when cultured separately.what does these results indicate?
Which vitamins participate, in coenzyme form, in reactions of the tricarboxylic acid cycle?
When it functions as a "second messenger", cAMP a) acts outside the cell to influence cellular processes. b) acts "second in importance" to AMP. c) activates all cytosolic protein kinases. d) activates the cAMP-dependent protein kinase.
Why is the t-butyloxycarbonyl protecting group such a good choice for amino acid synthesis?
what is meant by codan optimisation m rna enrichment?
