Which pair exhibits linkage isomerism?
SCN− binds via S or N, showing linkage isomerism.
Ref: NCERT Class 12 Chemistry > Chapter 5: Coordination Compounds > Topic: Isomerism - Optical Isomerism and Linkage Ionisation Solvate
#ligand binding
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Riboswitch ligand binding occurs at
A canonical riboswitch comprises two functionally separable domains fused in single transcript. The 5' aptamer domain folds into highly specific pocket with conserved nucleotides and tertiary interactions that selectively bind metabolite via hydrogen bonding and stacking with nanomolar to micromolar affinity. Aptamer architecture often pre-organized to reduce entropic cost of binding. Ligand recognition stabilizes alternative base-pairing pattern in adjacent expression platform downstream. As sensor module, aptamer itself does not regulate but communicates ligand occupancy through allosteric s
Ref: Alberts et al., Molecular Biology of the Cell, 7th ed., Chapter 6: RNA Regulation, Riboswitch Aptamer Domain
Loss of receptor-mediated signal transduction of ligand is most likely due to which mutations?
B and C, is consistent with established principles of cell signaling, receptor pharmacology and cellular regulation. Experimental measurements of binding parameters, genetic loss-of-function studies and pharmacological interventions all converge on the same interpretation. Related options address neighboring concepts but do not satisfy the precise criterion stated in the question.
Ref: NCERT Biology Class 11–12 Alberts et al Molecular Biology of the Cell Lodish et al, Molecular Cell Biology Cooper & Hausman, The Cell Abbas et al., Cellular and Molecular Immunology (for immunology sections)
Insulin receptor exists in which state before ligand binding?
Preformed dimer, is consistent with established principles of cell signaling, receptor pharmacology and cellular regulation. Experimental measurements of binding parameters, genetic loss-of-function studies and pharmacological interventions all converge on the same interpretation. Related options address neighboring concepts but do not satisfy the precise criterion stated in the question.
Ref: NCERT Biology Class 11–12 Alberts et al Molecular Biology of the Cell Lodish et al, Molecular Cell Biology Cooper & Hausman, The Cell Abbas et al., Cellular and Molecular Immunology (for immunology sections)
RTKs are activated mainly by
ligand-induced dimerization, is consistent with established principles of cell signaling, receptor pharmacology and cellular regulation. Experimental measurements of binding parameters, genetic loss-of-function studies and pharmacological interventions all converge on the same interpretation. Related options address neighboring concepts but do not satisfy the precise criterion stated in the question.
Ref: NCERT Biology Class 11–12 Alberts et al Molecular Biology of the Cell Lodish et al, Molecular Cell Biology Cooper & Hausman, The Cell Abbas et al., Cellular and Molecular Immunology (for immunology sections)
Hill plot is used to study
The Hill plot is a logarithmic transformation used to quantify cooperativity in ligand binding. The slope of the linear region, the Hill coefficient nH, exceeds unity for positive cooperativity and is less than unity for negative cooperativity. An nH of 1 recovers the non-cooperative Langmuir isotherm. The analysis therefore provides a convenient numerical index of cooperative interactions among binding sites.
Ref: NCERT Biology Class 11–12 Alberts et al Molecular Biology of the Cell Lodish et al, Molecular Cell Biology Cooper & Hausman, The Cell Abbas et al., Cellular and Molecular Immunology (for immunology sections)
Cell surface receptors mainly bind
Hydrophilic ligands cannot cross the plasma membrane and therefore bind cell-surface receptors that transmit the signal into the cell. Hydrophobic ligands such as steroid hormones readily diffuse across the bilayer and bind intracellular receptors that often function as ligand-activated transcription factors. This physicochemical distinction dictates the location and primary mechanism of receptor action.
Ref: NCERT Biology Class 11–12 Alberts et al Molecular Biology of the Cell Lodish et al, Molecular Cell Biology Cooper & Hausman, The Cell Abbas et al., Cellular and Molecular Immunology (for immunology sections)
Higher Kd means
The equilibrium dissociation constant Kd is the ratio of the dissociation rate constant to the association rate constant. A higher numerical value of Kd therefore indicates that dissociation is favored relative to association, resulting in weaker net binding. Affinity is consequently the reciprocal of Kd. This inverse relationship is fundamental to the quantitative interpretation of all reversible ligand–receptor interactions.
Ref: NCERT Biology Class 11–12 Alberts et al Molecular Biology of the Cell Lodish et al, Molecular Cell Biology Cooper & Hausman, The Cell Abbas et al., Cellular and Molecular Immunology (for immunology sections)
Equilibrium dialysis is used to study
Equilibrium dialysis separates free ligand from receptor-bound ligand by a semi-permeable membrane that retains the macromolecule. After equilibrium is established, measurement of ligand concentrations on both sides of the membrane allows calculation of bound and free concentrations. The method remains a classical, assumption-light approach for determining binding isotherms and extracting Kd and Bmax values.
Ref: NCERT Biology Class 11–12 Alberts et al Molecular Biology of the Cell Lodish et al, Molecular Cell Biology Cooper & Hausman, The Cell Abbas et al., Cellular and Molecular Immunology (for immunology sections)
Negative slope in Scatchard plot indicates
Because the Scatchard slope equals –1/Kd, the negative sign is an intrinsic feature of the plot for any saturable binding interaction. The absolute magnitude of the slope is the reciprocal of Kd and therefore reports affinity. A larger absolute value of the negative slope indicates higher affinity. The sign itself does not convey additional information beyond the inverse relationship with the dissociation constant.
Ref: NCERT Biology Class 11–12 Alberts et al Molecular Biology of the Cell Lodish et al, Molecular Cell Biology Cooper & Hausman, The Cell Abbas et al., Cellular and Molecular Immunology (for immunology sections)
Scatchard plot uses bound/free ligand on
In the classic Scatchard representation the ratio of bound ligand to free ligand is plotted on the ordinate (y-axis) against the concentration of bound ligand on the abscissa. This arrangement yields a straight line whose slope equals –1/Kd and whose x-intercept equals total receptor number. Correct orientation of the axes is required for proper interpretation of affinity and capacity parameters.
Ref: NCERT Biology Class 11–12 Alberts et al Molecular Biology of the Cell Lodish et al, Molecular Cell Biology Cooper & Hausman, The Cell Abbas et al., Cellular and Molecular Immunology (for immunology sections)
Equation for fractional saturation is
Fractional saturation Y is defined as the concentration of ligand-bound receptor divided by the total receptor concentration, Y = [RL]/([R] + [RL]). Under equilibrium mass-action kinetics this expression simplifies to Y = [L]/(Kd + [L]). The equation predicts a hyperbolic binding isotherm whose midpoint occurs when free ligand concentration equals Kd, providing a direct experimental route to affinity determination.
Ref: NCERT Biology Class 11–12 Alberts et al Molecular Biology of the Cell Lodish et al, Molecular Cell Biology Cooper & Hausman, The Cell Abbas et al., Cellular and Molecular Immunology (for immunology sections)