Biochemistry: Lecture 2 Flashcards
(17 cards)
Which of the following best describes the relationship between a hormone and its receptor?
A) Enzyme-substrate interaction
B) Antibody-antigen type relationship
C) Ligand-gated ion channel binding
D) Second messenger cascade activation
B) Antibody-antigen type relationship
All hormone receptors possess at least two functional domains. Which of the following accurately describes these domains and their functions?
A) Catalytic domain for signal amplification and binding domain for hormone inactivation.
B) Recognition domain responsible for binding the hormone ligand and effector domain for downstream protein modification.
C) Recognition domain that binds the hormone ligand and a signaling region that couples hormone recognition to an intracellular function.
D) Transmembrane domain for cellular localization and a regulatory domain for receptor internalization.
C) Recognition domain that binds the hormone ligand and a signaling region that couples hormone recognition to an intracellular function.
The response of a target cell to a hormone is LEAST dependent on which of the following factors?
A) The number of available receptors on the cell surface.
B) The concentration of the circulating hormone.
C) The presence of other hormones that do not bind to the receptor.
D) The presence of agonists or antagonists for the receptor.
C) The presence of other hormones that do not bind to the receptor.
Down-regulation of hormone receptors leads to which of the following cellular responses?
A) Increased sensitivity to the biosignaling agent.
B) A prolonged and enhanced response to the hormone.
C) Decreased sensitivity to the biosignaling agent, preventing overreaction from prolonged exposure.
D) An increase in the number of receptors on the cell surface.
C) Decreased sensitivity to the biosignaling agent, preventing overreaction from prolonged exposure.
Give an example of a disease that has a down- regulation mechanism of hormone receptors.
Type II DM
The decrease in insulin receptors in muscle cells saturated with glycogen is an example of:
A) Up-regulation
B) Desensitization with constant receptor numbers
C) Down-regulation
D) Increased gene expression of insulin receptors
C) Down-regulation
Which of the following is a characteristic of desensitization in the context of hormone receptors?
A) An increase in the number of receptors on the cell surface.
B) A decrease in the rate of receptor removal from the cell surface.
C) The number of receptors present typically remains constant.
D) Increased hormone binding affinity to its receptor.
C) ) The number of receptors present typically remains constant.
Other characteristics:
— Hydrophilic hormone enhance internalization of bound surface receptors
— lipophilic hormones have inhibitor proteins that inhibit the HR complex inhibiting the signaling of the receptors.
Radioimmunoassay (RIA) is a technique used for hormone quantitation that relies on:
A) The enzymatic conversion of a substrate to produce a detectable signal.
B) The fluorescence properties of the hormone molecule itself.
C) The competition between radioactive and unlabeled antigen for antibody binding sites.
D) The agglutination of particles coated with hormone in the presence of specific antibodies.
C) The competition between radioactive and unlabeled antigen for antibody binding sites.
In a Radioimmunoassay (RIA), the amount of antibody-bound radioactive antigen is typically measured to:
A) Directly quantify the concentration of the unlabeled antigen in the sample.
B) Determine the total amount of antigen present in the sample, both labeled and unlabeled.
C) Assess the nonspecific binding of the radioactive antigen in the absence of antibody.
D) Indirectly quantify the concentration of the unlabeled antigen by observing its displacement of the radioactive antigen.
D) Indirectly quantify the concentration of the unlabeled antigen by observing its displacement of the radioactive antigen.
Enzyme-linked Immunosorbent Assay (ELISA) differs from Radioimmunoassay (RIA) primarily in:
A) The requirement for highly purified antigen or antibody preparations.
B) The principle of direct binding between an antibody and its antigen.
C) The method used for detection of the bound analyte (enzymatic reaction vs. radioactivity).
D) The ability to generate a standard curve for quantitative measurements.
C) The method used for detection of the bound analyte (enzymatic reaction vs. radioactivity).
A major advantage of using an ELISA over an RIA for hormone measurement is:
A) Higher accuracy and specificity in hormone detection.
B) The long half-life of the detection label compared to radioactive isotopes.
C) Lower cost and complexity of the assay procedure.
D) The ability to directly measure the biological activity of the hormone.
B) The long half-life of the detection label compared to radioactive isotopes.
Other advantages:
No exposure to radioactivity
Easier to adapt into kits that RIA
RIA advantage: More specific
Which of the following can cause immunoassays to not always correlate with the biological activity of hormones?
A) The inability of immunoassays to detect hormones at low plasma levels.
B) The lack of specificity of antibodies for their target hormone.
C) The presence of hormone-binding plasma proteins that may render hormones inactive but still measurable by RIA.
D) The instability of hormones during the immunoassay procedure.
C) The presence of hormone-binding plasma proteins that may render hormones inactive but still measurable by RIA.
A Scatchard plot is a graphical representation used to analyze:
A) The enzymatic activity of hormone receptors.
B) The pharmacokinetic properties of hormones.
C) Receptor-ligand binding assay parameters.
D) The gene expression levels of hormone receptors.
C) Receptor-ligand binding assay parameters.
List the conditions need to utilized the Scatchhard Plot.
- Identical binding sites
- Binding of receptor to binding site must not change the affinity of the other free ones.
- Must follow the law of mass order
- Steady state equilibrium
In a Scatchard plot, the slope of the linear relationship between bound/free ligand concentration and bound ligand concentration is related to:
A) The total number of ligand-binding sites (n).
B) The maximum binding capacity (VMAX).
C) The affinity constant (Ka) or dissociation constant (Kd).
D) The rate of ligand-receptor association.
C) The affinity constant (Ka) or dissociation constant (Kd).
A key assumption underlying the classic Scatchard plot interpretation is:
A) The presence of multiple ligand-binding sites with different affinities.
B) Negative cooperativity between ligand-binding sites.
C) That the receptor has identical and noncooperative binding sites for the ligand.
D) That measurements are taken under non-equilibrium conditions.
C) That the receptor has identical and noncooperative binding sites for the ligand.
What can be inferred from a curved Scatchard plot?
A) The presence of a single class of non-interacting binding sites.
B) That the receptor-ligand interactions strictly obey the law of mass action.
C) The existence of two or more ligand-binding sites with different affinities or homogenous sites with negative cooperative binding.
D) That the measurements were performed at steady-state equilibrium.
C) The existence of two or more ligand-binding sites with different affinities or homogenous sites with negative cooperative binding.
