Biochemistry LE 1: Introduction to Hormones

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What is the typical concentration range of hormones and other signals?

Micromolar (10–6 mol/L)

Molar (1 mol/L)

Millimolar (10–3 mol/L)

Nanomolar (10–9 mol/L) or picomolar (10–12 mol/L) (correct)

What is the purpose of multilayered signal transduction cascades?

To delay the signal

To amplify the original signal (correct)

To reduce the original signal

To change the type of signal

What is the role of the receptor in signal transduction?

Only signal transducer

Both signal transducer and signal amplifier (correct)

Only signal amplifier

Neither signal transducer nor signal amplifier

What is the product of the reaction catalyzed by adenylate cyclase?

cAMP Signup and view all the answers

What is activated by cAMP?

Protein kinase A Signup and view all the answers

What is the result of protein kinase A phosphorylating proteins?

Very large amplification Signup and view all the answers

What is the reactant in the cyclization reaction catalyzed by adenylate cyclase?

ATP Signup and view all the answers

What type of bond is formed in the cyclization reaction?

Phosphodiester bond Signup and view all the answers

What happens to blood glucose levels when glycolysis is suppressed and gluconeogenesis is increased?

Increased Signup and view all the answers

What is activated in the presence of light in the process of vision?

Rhodopsin Signup and view all the answers

What is the effect of increased GMP levels on Na+ channels?

Closure Signup and view all the answers

What is the role of phosphodiesterase in the phototransduction cascade?

Conversion of cGMP to GMP Signup and view all the answers

What is the effect of hyperpolarization on neurotransmitter release?

Decreased release Signup and view all the answers

What happens to the hormone-receptor complex after it forms?

It binds to certain segments of DNA Signup and view all the answers

What is the outcome of the transmission of light impulses to the brain?

Visual interpretation Signup and view all the answers

What happens to the Na+ channels in the dark state?

Opening Signup and view all the answers

What is the result of transcription and translation of the hormone-receptor complex in the nucleus?

Protein synthesis Signup and view all the answers

What is the outcome of the recovery of the rods and cones in the dark state?

Recovery into a passive, dark, and inactive state Signup and view all the answers

What does KD represent in the kinetics of hormone-receptor binding?

The hormone concentration at which half of the receptors are filled Signup and view all the answers

What is the characteristic of the upward slope of the hyperbolic curve?

First-order kinetics Signup and view all the answers

What happens to the reaction at point C in the kinetics of hormone-receptor binding?

The reaction reaches saturation point Signup and view all the answers

What is the relationship between Bmax and KD?

Bmax and KD are similar to Vmax and Km of simple enzymes Signup and view all the answers

What is the function of receptors in hormone signaling?

To transmit signals from hormones Signup and view all the answers

What type of protein are receptors in hormone signaling?

Transmembrane protein Signup and view all the answers

What is the typical state of an Intrinsic Tyrosine Kinase Receptor (ITKR) in the absence of hormone binding?

Monomer Signup and view all the answers

What event triggers the transfer of the γ-phosphate group from ATP via the ITKR activity?

Dimerization of the receptor Signup and view all the answers

What is the role of phosphorylated tyrosine in the signaling pathway?

To serve as a docking site for the intracellular signal transducer or adaptor protein Signup and view all the answers

What is the function of the Intrinsic Tyrosine Kinase Receptor (ITKR) in insulin signaling pathways?

To regulate glucose uptake Signup and view all the answers

What is the structure of the insulin receptor?

Dimer Signup and view all the answers

What is the result of tyrosine phosphorylation in insulin signaling pathways?

Recruitment of multiple adaptor proteins Signup and view all the answers

What is the result of insulin binding to the ITKR?

Dimerization of the receptor Signup and view all the answers

What is the function of SH2 domain-containing proteins in insulin signaling pathways?

To serve as intracellular signal transducers or adaptors Signup and view all the answers

What is the composition of the insulin receptor in the membrane?

A preformed dimer with each half containing an α- and a β-subunit Signup and view all the answers

What happens to the tyrosine residues in the cytoplasmic domain after insulin binding?

They undergo phosphorylation Signup and view all the answers

What is the effect of autophosphorylation of β-subunits?

Activation of the receptor Signup and view all the answers

What binds to the phosphotyrosines on the receptor?

IRS and SH2 Signup and view all the answers

What is the outcome of phosphorylation of tyrosine residues?

Activation of signal transduction Signup and view all the answers

What is the final outcome of the signaling cascade initiated by insulin binding?

Activation of gene expression Signup and view all the answers

What is the role of insulin receptor substrate (IRS)?

To activate insulin signaling Signup and view all the answers

What is the location of the tyrosine kinase activity?

In the cytoplasmic domain Signup and view all the answers

What is the effect of insulin binding to its receptor?

Dimerization and phosphorylation of tyrosine residues Signup and view all the answers