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Biochem Flashcards

1
Q

Which hormone increases water absorption in the kidneys? A. Aldosterone B. Androgens C. Cortisol D. PTH E. Calcitonin

A

Aldosterone

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2
Q

ACTH stimulates the secretion of which of the following? A. Glucocorticoids B. Epinephrine C. Thyroxine D. Luteinizing hormone

A

Glucocorticoids

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3
Q

Which of the following is false information about growth hormone? A. Acts on the liver, stimulating it to release several polypeptide hormones B. Stimulates amino acid uptake and protein synthesis in target cells C. Stimulates cell growth (cell size and number), especially in muscle and bone D. It has no role in fat breakdown E. Stimulates protein synthesis

A

has no role in fat breakdown

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4
Q

Steroid hormone precursors are converted to active hormones and diffuse out of the parent cell by which of the following pathways? A. Simple diffusion B. Facilitated diffusion C. Exocytosis D. Carrier proteins E. Na+-K+ ion channels

A

Simple diffusion

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5
Q

Increased reabsorption of water from the kidney is the major consequence of which of the following hormones? A. Cortisol B. Insulin C. Vasopressin
D. Aldosterone E. Glucagon

A

Vasopressin

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6
Q

Which of the following is the pituitary hormone that triggers the release of thyroid hormone from the thyroid gland? A. Thyroid stimulating hormone (TSH) B. Adrenocorticotropic hormone (ACTH) C. Follicle stimulating hormone (FSH) D. Luteinizing hormone (LH) E. Growth hormone (GH)

A

Thyroid stimulating hormone (TSH)

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7
Q

Growth hormone is released by which of the following? A. Somatostatin B. Growth hormone releasing hormone C. Prolactin release inhibiting hormone D. Luteinizing releasing hormone

A

Growth hormone releasing hormone

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8
Q

ACTH stimulates the secretion of which of the following? A. Glucocorticoids B. Epinephrine C. Thyroxine D. Luteinizing hormone

A

Glucocorticoids

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9
Q

Beta-cells of islet of Langerhans of the pancreas secrete which hormone? A. Insulin B. Glucagon C. Somatostatin D. Pancreatic polypeptide

A

Insulin

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10
Q

Which is the target tissue of insulin? A. Red blood cells B. Renal tubular cells C. GI tract epithelial cells D. Liver

A

D. Liver

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11
Q

Untreated diabetes mellitus results in what condition? A. Rapid uptake of sugar B. Low blood glucose level C. Decrease urine output D. Presence of glucose in urine

A

Presence of glucose in urine

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12
Q

Changes in what condition increase the primary stimulus for insulin secretion? A. Blood level of epinephrine B. Blood level of glucagon C. Blood level of glucose D. Water intake

A

Blood level of glucose

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13
Q

Hormone receptors possess all the following properties except which one? A. All of them are proteins B. They possess a recognition domain C. They bind hormones with a high degree of specificity D. Number of receptors in a target cell is constant

A

D. Number of receptors in a target cell is constant

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14
Q

Melatonin is synthesized in which part of the body? A. Hypothalamus B. Posterior pituitary gland C. Pineal gland D. Melanocytes

A

Pineal gland

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15
Q

Which hormone is secreted from anterior pituitary? A. Growth hormone B. Vasopressin C. Oxytocin D. Epinephrine E. Glucagon

A

Growth hormone

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16
Q

Which of the following is not one of the anterior pituitary hormones? A. Growth hormone B. Thyroid stimulating hormone C. Adrenocorticotropic hormone
D. Antidiuretic hormone E. Gonadotropins

A

Antidiuretic hormone

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17
Q

Acromegaly results due to excessive release of which of the following? A. Thyroxine B. Growth hormone C. Insulin D. Glucagon E. Noradrenaline

A

Growth hormone

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18
Q

ACTH stimulates the secretion of which of the following? A. Glucocorticoids B. Prolactin C. Thyroxine D. Luteinizing hormone E. Oxytocin

A

Glucocorticoids

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19
Q

Epinephrine stimulates glycogenolysis in which organ? A. Liver B. Muscle C. Liver and muscle D. Kidney E. Brain

A

Liver and muscle

20
Q

Excess secretion of thyroid hormones causes what disease state? A. Hyperthyroidism B. Myxoedema C. Cretinism D. Cushing syndrome E. Dwarfism

A

Hyperthyroidism

21
Q

-cells of islet of Langerhans of the pancreas secrete which hormone? A. Insulin B. Glucagon C. Somatostatin
D. Pancreatic polypeptide E. Triiodotronine

A

Insulin

22
Q

A 43-year-old man comes to the emergency room with a headache and blurred vision. He complains that his wedding ring no longer fits him, and that his favorite hat no longer fits on his head. His wife feels that his nose has become wider, and he is diagnosed acromegaly. Which of the following metabolic effects would you expect in this patient? A. Decreased protein synthesis B. Inhibition of gluconeogenesis C. Inhibition of lipolysis D. Increased protein synthesis E. Gigantism

A

Increased protein synthesis

23
Q

A 13-year-old boy has developed polydipsia, polyuria, polyphagia, and weight loss over the past few weeks. He was brought to the emer- gency room by his parents because he woke up this morning very lethargic. His blood glucose was found to be 600 mg/dL, and he was immediately placed on an insulin drip. Insulin works primarily by which one of the following mechanisms? A. Activating adenylate cyclase B. Binding to an intracellular receptor C. Activating caspases D. Producing cGMP A. Causing phosphorylation of tyrosine residues

A

Causing phosphorylation of tyrosine residues

24
Q

What molecules enable cells to respond to a specific extracellular signalling molecule? A. Specific receptor carbohydrates localized to the inner plasma membrane surface B. Plasma lipid bilayer C. Ion channels D. Receptors that specifically recognize and bind that particular messenger molecule E. Intact nuclear membranes

A

Receptors that specifically recognize and bind that particular messenger molecule

25
Q

Indicate the term generally applies to the extracellular messenger molecules that bind to transmembrane receptor proteins. A. Competitive inhibitor B. Ligand
C. Scatchard curve D. Substrate E. Cofactor

A

Ligand

26
Q

Regardless of how a signal is initiated, the ligand-binding event is propagated via second messengers or protein recruitment. What is the ultimate, or final biochemical outcome of these binding events? A. A protein in the middle of an intracellular signaling pathway is activated B. A protein at the bottom of an intracellular signaling pathway is activated C. A protein at the top of an extracellular signaling pathway is activated D. A protein at the top of an intracellular signaling pathway is deactivated E. A protein at the top of an intracellular signaling pathway is activated

A

A protein at the bottom of an intracellular signaling pathway is activated

27
Q

What features of the nuclear receptor superfamily suggest that these proteins have evolved from a common ancestor? A. They all bind the same ligand with high affinity B. They all function within the nucleus C. They are all subject to regulatory phosphorylation. D. They all contain regions of high amino acid sequence similarity/identity E. They all bind DNA

A

They all contain regions of high amino acid sequence similarity/identity

28
Q

What effect does degradation of receptor-ligand complexes after internalization have upon the ability of a cell to respond if immediately re-exposed to the same hormone? A. The cellular response is attenuated due to a decrease in cellular receptor number B. Cellular response is enhanced due to reduced receptor-ligand competition. C. The cellular response is unchanged to subsequent stimuli D. Cell hormone response is now bimodal; enhanced for a short time and thereafter inactivated

A

The cellular response is attenuated due to a decrease in cellular receptor number

29
Q

Typically, what is the first reaction after most receptor protein-tyrosine kinases (RTKs) bind their ligand? A. Receptor trimerization
B. Receptor degradation C. Receptor denaturation D. Receptor dissociation E. Receptor dimerization

A

Receptor dimerization

30
Q

Where is the kinase catalytic domain of the receptor protein-tyrosine kinases found? A. On the extracellular surface of the receptor, immediately adjacent to the ligand-binding domain B. On the cytoplasmic domain of the receptor C. On an independent protein that rapidly binds the receptor upon ligand binding D. Within the transmembrane spanning portion of the receptor

A

On the cytoplasmic domain of the receptor

31
Q

The subunits of the heterotrimeric G-proteins are called the __, __, and__ subunits. A. α, β, and χ B. α, β, and δ C. α, γ, and δ D. α, β, and γ E. γ, δ, and η

A

α, β, and γ

32
Q

Of the receptors listed below, which can directly conduct a flow of ions across the plasma membrane when bound to their cognate ligand? A. Receptor tyrosine kinases (RTKs) B. G-protein–coupled receptors (GPCRs) C. G-protein gamma α subunit. D. Steroid hormone receptors E. Ligand-gated channels

A

Ligand-gated channels

33
Q

Which of the following is not a natural ligand that binds to G protein–coupled receptors? A. Hormones B. Steroid hormones C. Chemo attractants
D. Opium derivatives E. Neurotransmitters

A

Steroid hormones

34
Q

Place the events of signalling listed below in the correct order. 1. G-protein binds to activated receptor forming a receptor–G-protein complex 2. Release of GDP by the G-protein 3. Change in conformation of the cytoplasmic loops of the receptor 4. Binding of GTP by the G-protein 5. Increase in the affinity of the receptor for a G-protein on the cytoplasmic surface of the membrane 6. Binding of a hormone or neurotransmitter to a G-protein–coupled receptor 7. Conformational shift in the α subunit of the G-protein
A. 6 – 3 – 5 – 1 – 2 – 4 – 7
B. 6 – 5 – 4 – 1 – 7 – 2 – 3
C. 6 – 3 – 5 – 1 – 7 – 2 – 4
D. 6 – 7 – 3 – 5 – 1 – 2 – 4
E. 6 – 3 – 5 – 4 – 7 – 2 – 1

A

6 – 3 – 5 – 1 – 7 – 2 – 4

35
Q

Which heterotrimeric G-proteins couple receptors to adenylyl cyclase via the activation of GTP-bound Gα subunits? A. Gs family B. Gq family C. Gi family D. G12/13 family E. Gx family

A

Gs family

36
Q

What must happen to prevent overstimulation by a hormone? A. Hormones must be degraded B. G-proteins must be recycled and then degraded C. Receptors must be blocked from continuing to activate G-proteins D. Receptors must dimerize

A

Receptors must be blocked from continuing to activate G-proteins

37
Q

Which hormone is secreted by α cells in the pancreas in response to low blood glucose levels? A. Insulin B. Glucagon C. Estradiol D. Epinephrine E. Somatostatin

A

Glucagon

38
Q

In liver cells, the expression of genes encoding gluconeogenic enzymes such as phosphoenolpyruvate carboxykinase is induced in response to which of the following molecules? A. cGMP B. Insulin C. ATP D. cAMP E. Cholesterol

A

cAMP

39
Q

What happens to protein kinase A (PKA) following the binding of cAMP? A. The regulatory subunits of PKA dissociate, thereby activating the catalytic subunits B. PKA catalytic subunits then bind to two regulatory subunits, thereby activating the catalytic subunits. C. The inhibitory regulatory subunits dissociate from the catalytic subunits, completely inactivating the enzyme D. The stimulatory regulatory subunits dissociate from the catalytic subunits, inhibiting the enzyme E. Phosphodiesterase binds to the catalytic subunits, which results in enzyme inactivation

A

The regulatory subunits of PKA dissociate, thereby activating the catalytic subunits

40
Q

Thyroid hormones are intimately involved in regulating the basal metabolic rate. Choose the wrong statement. A. Excess thyroxine shows an increased rate of O2 consumption. B. Excess thyroxine shows increased heat output (thermogenesis)
C. Excess thyroxine decreases the ATP concentration in the tissue D. Excess thyroxine causes uncoupling of oxidative phosphorylation in mitochondria E. Thermogenesis is due to an increased rate of ATP utilization by the thyroxine-stimulated tissue

A

Excess thyroxine decreases the ATP concentration in the tissue

41
Q

If a single gene contains information for synthesis of more than one hormone molecule which statement is correct? A. All the hormones are produced by any tissue that expresses the gene B. All hormone molecules are identical C. Cleavage sites in the gene product are typically pairs of basic amino acids D. All peptides of the gene product have well-defined biological activity E. Hormones all have similar function

A

Cleavage sites in the gene product are typically pairs of basic amino acids

42
Q

In the interaction of a hormone with its receptor, all of the following are true except which one? A. More than one polypeptide chain of the hormone may be necessary B. More than one second messenger may be generated C. An array of transmembrane helices may form the binding site for the hormone D. Receptors have a greater affinity for hormones than for synthetic agonists or antagonists E. Hormones released from their receptor after endocytosis could theoretically interact with a nuclear receptor.

A

Receptors have a greater affinity for hormones than for synthetic agonists or antagonists

43
Q

Some hormone-receptor complexes are internalized by endocytosis. This process may involve which of the following? A. Binding of hormone-receptor complex to a clathrin coated pit B. Recycling of receptor to cell surface C. Degradation of receptor and hormone in lysosomes D. Formation of a receptosome E. All of the above

A

All of the above

44
Q

Binding of insulin to its receptor occurs on/results in which of the following? A. Occurs on the β-subunit B. Induces autophosphorylation C. Reduces binding of cytosolic substrate proteins D. Leads only to phosphorylation of proteins E. Does not lead to release of a second messenger

A

Induces autophosphorylation

45
Q

All the following are normal events leading to secretion of aldosterone from the adrenal gland except which one? A. Renin is released by the kidney in hypovolemia B. Angiotensinogen binds to membrane receptors C. The PI cycle is activated producing IP3 and DAG D. Ca2+ levels in the cell rise E. Aldosterone is secreted into the blood

A

Angiotensinogen binds to membrane receptors

46
Q

In hypopituitarism the ovarian cycle would be affected because of the following events? A. FSH and LH are synthesized in the anterior pituitary B. Gonadotropin-releasing hormone (GnRH) from the hypothalamus stimulates the release of FSH and LH C. Inhibins would be secreted in much larger than normal amounts D. The corpus luteum would be maintained E. GnRH would bind co receptors to activate protein kinase A

A

FSH and LH are synthesized in the anterior pituitary

47
Q

The PI cycle begins with activation of phospholipase C; this initiates a sequence of events including all of the following except which one? A. Activation of IP3 by action of a phosphatase B. Increase in intracellular Ca2+ concentration C. Release of diacylglycerol (DAG) D. Activation of protein kinase C E. Phosphorylation of certain cytoplasmic proteins

A

Activation of IP3 by action of a phosphatase

305 (6 decks)

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