Description : Binding of insulin to its receptor activates (A) Adenylate cyclase (B) Guanylate cyclase (C) Phospholipase C (D) Tyrosine kinase
Last Answer : Answer : D
Description : Which of the following statement(s) is/are true concerning cell membrane receptors? a. The largest family of cell surface receptors are the G-protein-linked receptors b. Activities of the ... through the use adenylate cyclase d. Tyrosine kinase receptors are considered G-protein-linked receptors
Last Answer : Answer: a, c All water-soluble regulatory molecules bind to the cell surface receptor proteins. Binding of the appropriate ligand evokes an intracellular signal which usually regulates ... are adenylate cyclase, which converts ATP to cAMP, and the polyphosphoinositide-specific phospholipase C
Description : Adenylate cyclase is activated by (A) GDP-bearing α-Subunit of G-protein (B) GTP-bearing α-Subunit of G-protein (C) GDP-bearing γ-Subunit of G-protein (D) GTP-bearing γ-Subunit of G-protein
Last Answer : Answer : B
Description : Rod cells possess a trans-membrane protein which is (A) Adenylate cyclase (B) Transducin (C) Rhodopsin (D) B as well as C
Last Answer : Answer : C
Description : The best understood intracellular messenger is cyclic AMP (cAMP). Which of the following statement(s) concerning this intracellular messenger is/are correct? a. Intracellular cyclic AMP is constantly ... of adenylate cyclase d. cAMP is the only cyclic nucleotide active as an intracellular messenger
Last Answer : Answer: a, b The prototypic intracellular messenger is cAMP. To function as a mediator, the concentration of cAMP must change rapidly. In resting cells, cAMP is continuously being degraded by ... produce cGMP. Intracellular calcium ions also serve as second messengers in a large number of cells
Description : Phosphorylated IRS-1 activates GRB-2 which is (A) G-protein receptor binding protein-2 (B) Growth factor receptor binding protein-2 (C) Growth hormone receptor binding protein-2 (D) Glucocorticoid receptor binding protein-2 226 MCQs IN BIOCHEMISTRY
Description : cAMD is destroyed by (A) Adenylate cyclase (B) Phosphodiesterase (C) Synthetase phosphatase (D) Synthetase kinase
Description : Whcih of the following hormone does not activate adenylate cyclase? (A) Epinephrine (B) Glucagon (C) Parathyroid hormone (D) Insulin
Description : Adenylate cyclase is activated by (A) Insulin (B) Glucagon (C) Prostaglandin E1 (D) Ca2+ ions
Description : Cyclic AMP is formed from ATP by the enzyme adenylate cyclase which is activated by the hormone: (A) Insulin (B) Epinephrine (C) Testosterone (D) Progesterone
Last Answer : B
Description : Which of the following is activated by Cholera toxin? 1) Adenylate cyclase 2) Guanlyate cyclase 3) Peroxisome proliferator receptor (PPAR) gamma 4) Sodium/potassium ATPase 5) The glucose-sodium transporter
Last Answer : Answers-1 Cholera toxin activates adenylate cyclase with generation of cAMP.
Description : Signal transducer for glucagons is a (A) Cyclic nucleotide (B) Phosphoinositide (C) Stimulatory G-protein (D) Inhibitory G-protein
Description : Transducin is a (A) Signal transducer (B) Stimulatory G-protein (C) Trimer (D) All of these
Description : The function of a repressor protein in an operon system is to prevent synthesis by binding to (A) The ribosome (B) A specific region of the operon preventing transcription of structural genes (C) The RNA polymerase (D) A specific region of the mRNA preventing translation to protein
Description : In the process of transcription in bacterial cells (A) Initiation requires rho protein (B) RNA polymerase incorporates methylated bases in correct sequence (C) Both the sigma unit and core ... RNA polymerase are required for accurate promotor site binding (D) Primase is necessary for initiation
Description : The only correct statement about hormone receptors is (A) Receptors for protein hormones are present in cytosol (B) Receptors for steroid hormones are membrane bound (C) Hormone-receptor binding is irreversible (D) Receptors can undergo down regulation and up regulatoin
Description : Binding of acetylcholine to its receptors increases the permeability of cell membrane to (A) Ca++ (B) Na+ (C) K+ (D) Na+ and K+
Description : Binding of gamma-aminobutyric acid to its receptors in brain increases the permeability of cell membrane to (A) Cl– (B) Na+ (C) K+ (D) Ca++
Last Answer : Answer : A
Description : Binding of catecholamines to α2− adrenergic receptors (A) Increases the intracellular concentration of cAMP (B) Increases the intracellular concentration of cGMP (C) Decreases the intracellular concentration of cAMP (D) Decreases the intracellular concentration of cGMP
Description : a2–adrenergic receptors are associated with following except (a) Increase in phospholipase C activity (b) Increase in potassium channel conductance (c) Decrease in calcium channel conductance (d) Increase in adenylyl cyclase activity
Last Answer : Ans: D
Description : Insulin increases the permeability of glucose across the plasma membrane of muscle cells by (A) Acting on adenylate cycle (B) By loosening the integrity of the membrane (C) Through Ca2 ... membrane cruting the hexose carries of intracellular organelles and making them fuse with the plasma membrane
Description : When thyroxine binding globulin and thyroxine binding pre-albumin are saturated with thyroxine, the excess hormone is transported by (A) Albumin (B) Gamma globulins (C) Transcortin (D) None of these
Description : Thyroid hormones are present in blood (A) In free form (B) In association with thyroxine binding globulin (TBG) (C) In association with thyroxine binding prealbumin (TBPA) (D) Mainly in association with TBG, partly in free form and sometimes in association with TBPA also
Description : Thyroperoxidase iodinates (A) Free tyrosine in thyroid gland (B) Tyrosine residues of thyroglobulin (C) Tyrosine residues of thyroxine binding globulin (D) Tyrosine residues of thyroxine binding prealbumin
Description : Which one of the following drugs is used in the treatment of male impotence and activates prostaglandin E1 receptors? (a) Alprostadil (b) Fluoxetine (c) Mifepristone (d) Sildenafil (e) Zafirlukast
Last Answer : Ans: A
Description : Which one of the following statements about dextromethorphan is accurate? (a) Activates kappa receptors (b) Analgesia equivalent to pentazocine (c) Highly effective antiemetic (d) Less constipation than codeine (e) Use requires a prescription
Description : In the treatment of parkinsonism, bromocriptine differs from levodopa in the following respects except: A. It does not need conversion to an active metabolite B. It has a longer duration of ... with little/antagonistic action on D1 receptors D. It does not produce behavioral/psychiatric side effect
Last Answer : D. It does not produce behavioral/psychiatric side effects
Description : Most hormone receptors are localized on the cell membrane and transduce hormone binding into altered levels of intracellular messengers. A limited number of intracellular receptors do exist. Which of ... protein serves as an inhibitor protein blocking the DNA-binding domain of the steroid receptor
Last Answer : Answer: a, d Although most hormone and other messenger receptors are extracellular, intracellular receptors have been identified. The hormone messengers involved for these receptors are primarily ... DNA-binding domain of the receptor. Activation involves the dissociation of the inhibitor protein
Description : Calcium is important in skeletal muscle contraction because it (a) binds to troponin to remove the masking of active sites on actin for myosin (b) activates the myosin ATPase by binding to it ... filament (d) prevents the formation of bonds between the myosin cross bridges and the actin filament.
Last Answer : (a) binds to troponin to remove the masking of active sites on actin for myosin
Description : Calcium is important in skeletal muscle contraction because it :- (1) binds to troponin to remove the masking of active sites on actin for myosin. (2) activates the myosin ATPase by binding to ... filament. (4) prevents the formation of bonds between the myosin cross bridges and the actin filament.
Last Answer : (1) binds to troponin to remove the masking of active sites on actin for myosin.
Description : The following is true of loperamide except: A. It is absorbed from intestines and exerts centrally mediated antidiarrhoeal action B. It acts on the opioid receptors in the gut C. It increases ... of the intestines D. It inhibits intestinal secretion by binding to calmodulin in the mucosal cells
Last Answer : A. It is absorbed from intestines and exerts centrally mediated antidiarrhoeal action
Description : Astimulatory G-protein transduces the signals from (A) α1-and β1-adrenergic receptors (B) α2-and β2-adrenergic receptors (C) α1-and α2-adrenergic receptors (D) β1-and β2-adrenergic receptors
Description : All the following statements about hormones are true except (A) All of them require specific carriers in plasma (B) All of them require specific receptors in target cells (C) Some of them are subject to feedback regulation (D) Some of them increase the transcription of certain genes
Description : Binding of growth hormone to its receptor results in increased transcription of (A) c-fos gene (B) c-myc gene (C) p-53 gene (D) None of these
Description : The ‘rho’ (ρ) factor is involved (A) To increase the rate of RNA synthesis (B) In binding catabolite repressor to the promoter region (C) In proper termination of transcription (D) To allow proper initiation of transcriptide
Description : Transcription of structural genes of lac operon is prevented by binding of the repressor tetramer to (A) i gene (B) Operator locus (C) Promoter (D) z gene
Description : Hormone receptors that stimulate cAMP production (A) are part of a complex of two proteins that transform the external signal into internal cAMP production (B) are proteins distinct and separate from those ... binding of the hormone (D) are not very specific and bind a number of different hormones
Description : Phosphoinositide cascade is activated on binding of catecholamines to (A) α1-Adrenergic receptors (B) α2-Adrenergic receptors (C) β1-Adrenergic receptors (D) β2-Adrenergic receptors
Description : The following are true about the thyroid hormone a. iodide ions enter the follicle cells by passive diffusion b .T4 and T3 bind to the receptors in nuclei c. thyroxine, once ... thyroglobulin until released d. a greater proportion of tri-iodothyronine is formed when iodine is deficient
Last Answer : T4 and T3 bind to the receptors in nuclei
Description : The receptor transduction mechanism with the fastest time-course of response effectuation is: A. Adenylyl cyclase-cyclic AMP pathway B. Phospholipase C-IP3: DAG pathway C. Intrinsic ion channel operation D. Protein synthesis modulation
Last Answer : C. Intrinsic ion channel operation
Description : Protein bound iodine is _________ bound to protein. (A) Iodine (B) Thyroid hormones (C) Thyroxine (D) Tri iodo thyronine
Description : Which of the following statements is correct? (A) Thyroxine inhibits utilization of glucose (B) Insulin increases utilization of glucose (C) Glucagon promotes muscle glycogenolysis (D) Insulin inhibits lipogenesis from carbohydrates
Description : Which does NOT occur in a cell stimulated by a steroid hormone? A) The steroid hormone enters the cell by crossing the plasma membrane. B) The hormone binds to a receptor molecule in the ... activates certain genes. E) DNA is transcribed, mRNA is translated, and the result is protein synthesis.
Last Answer : C) The second messenger cyclic AMP is stimulated by the hormone-receptor complex. D) The hormone-receptor complex binds the chromatin and activates certain genes.
Description : a1 – receptors are coupled with _______ G protein. (a) Gs (b) Gi (c) Gq (d) Go
Last Answer : Ans: C
Description : The following are true about the aqueous: a. the protein content of aqueous is about 1/5 that of the plasma b. the main type of protein found in the aqueous is transferrin c. Ig G is found in the aqueous d. stimulation of 2 receptors reduces aqueous production
Last Answer : stimulation of 2 receptors reduces aqueous production
Description : Which one of the following drugs does NOT act through G-Protein coupled receptors? (A) Epinephrine (B) Insulin (C) Dopamine (D) TSH
Last Answer : (B) Insulin
Description : The following statement about histamine is not correct: A. It is the sole mediator of immediate hypersensitivity reaction B. It plays no role in delayed hypersensitivity reaction C. It serves as a neurotransmitter in the brain D. All types of histamine receptors are G protein coupled receptors
Last Answer : A. It is the sole mediator of immediate hypersensitivity reaction
Description : Agonist induced autophosphorylation, internalization and down regulation is a distinctive feature of: A. G-protein coupled receptors B. Intrinsic ion channel containing receptors C. Tyrosine protein kinase receptors D. Receptors regulating gene expression
Last Answer : C. Tyrosine protein kinase receptors