Which statement best describes the pKa of amino groups in proteins?
pKa of the α-amino group is higher than the pKa of ε- amino group.
pKa of the α-amino group is lower than the pKa of ε- amino group.
pKa of the α-amino group is the same as the pKa of ε- amino group.
pKa of the α-amino group is higher than the pKa of the guanidine side chain of arginine.
B.
pKa of the α-amino group is lower than the pKa of ε- amino group.
Among the given statements, statement 4 describes the pKa amino groups in proteins.
Which one of the following non-covalent interactions between two non-bonded atoms A and B is most sensitive to the distance between them?
A and B are permanent dipoles and are involved in hydrogen bonding
A and B are fully ionized and are involved in salt bridge formation
A and B are uncharged and repel each other.
A and B are uncharged and attract each other
A protein has 30% alanine. If all the alanines are replaced by glycines.
helical content will increase
β-sheet content will increase
there will be no change in conformation
the alanine-substituted protein will be less structured than the parent protein
σ-subunit of E. coli RNA Polymerase DOES NOT
initiate transcription and fall off during elongation.
increase affinity of the core enzyme to the promoter
binds to DNA, independent of the core enzyme
ensures specificity of transcription by interacting with the core enzyme
Origin of replication usually contains
GC rich sequences
Both AT and GC rich sequences
No particular stretch of sequences
AT rich sequences
You have created a fusion between the top operon, which encodes the enzymes for tryptophan biosynthesis, under the regulatory control of the lac operator. Under which of the following conditions will tryptophan synthase be induced in the strain that carries the chimeric operator fused operons?
only when both lactose and glucose are absent
only when lactose is absent and glucose are present
only when lactose is absent and glucose is present
only when lactose is present and glucose is absent.
Which of the following pairs of subcellular compartments is likely to have the same pH and electrolyte composition?
cytosol and lysosomes
cytosol and mitochondrial intermembrane space
cytosol and endosome
mitochondrial matrix and intermembrane space.
What is the effect of 2, 4-dinitrophenol on mitochondria?
Blocks ATP synthesis without inhibiting electron transport by dissipating the proton gradient.
Blocks electron transport and ATP synthesis by inhibiting ATP-ADP exchange across the inner mitochondrial membrane.
Blocks electron transport and proton pumping at complexes I, II and III
interacts directly with ATP synthase and inhibits its activity.
The gel to liquid crystalline transition temperature (Tm) of phospholipids is dependent on the fatty acid composition. Considering this, Tm of
all the phospholipids will be identical
DPPC will be lowest and DOPC will be highest.
POPC and DOPC will be identical and lower than DMPC or DPPC
DOPC will be lowest and DPPC will be highest.
Regarding microtubule assembly and disassembly during cell division, which will be the most appropriate answer?
Once formed, kinetochore microtubules depolymerize at the plus ends throughout mitosis.
Once formed, kinetochore microtubules polymerize at the plus ends throughout mitosis.
Kinetochore microtubules polymerize at their plus ends up to anaphase, at which point they begin to depolymerize.
Kinetochore microtubules polymerize at their minus ends up to cytokinesis, at which point they depolymerize.