Exam 5 Review:  Chapter 16:  Hormone Biochemistry

biogenic amines - A diverse group of small molecules, derived from precursors which are amino acids, which play regulatory roles in various cellular metabolic pathways; included are amine hormones and amine neurotransmitters.

tyrosine - A phenolic amino acid C₉H₁₁NO₃ that is a precursor of several important substances (as epinephrine and melanin

peptide hormone - Any member of the chemical group or subgroup of hormones which are synthesized by covalently linking a few, approximately a dozen (from 3 to ~20), amino acids together in a chain.

protein hormone - Any member of the chemical group or subgroup of hormones which are synthesized by covalently linking a many (>20, usually more than a hundred), amino acids together in a chain.

eicosanoids - Any of a class of local hormone compounds, e.g., prostaglandins, leukotrienes, and thromboxanes, derived from polyunsaturated fatty acids, typically from arachidonic acid, a cell membrane lipid, and involved regulating target cellular activity

transport proteins - Integral proteins of cell membranes which assist in the movement of molecules across cell membranes; they are highly selective and specific as to the ions or molecules they can assist; they may participate in passive or active transport mechanisms and may be in the form of carriers, channels, or transporters.

lipid soluble hormones - A descriptive name for those hormones which will dissolve in nonpolar solvents; the most common examples are the steroid hormones synthesized from cholesterol.

steroids - The group name for those lipid-soluble hormones and drugs which are synthesized using the cholesterol molecule as the precursor substance.

cyclic AMP (cAMP) - A cyclic monophosphate mononucleotide of adenosine which is formed from ATP by the catalytic action of the enzyme adenyl cyclase and which, as a second messenger, is responsible for the intracellular mediation (usually a stimulatory control) of hormonal effects on various cellular processes, e.g., lipid metabolism, membrane transport, and cell proliferation.

protein kinases - A diverse group of regulatory cellular proteins which are enzymes which take other cellular proteins as their substrates and either phosphorylate or dephosphorylate those substate proteins to increase or decrease their metabolic activity; protein kinases play an intermediate role in the action of hormone stimulated enzyme cascades.

G proteins - Any of a group of integral proteins in cell membranes which, upon activation by the arrival and binding of a hormone to its cell surface receptor, initiate a series of molecular events inside the cell membrane which lead to the formation of a cytoplasmic second messenger substance.

cyclic GMP  (cGMP) - A cyclic monophosphate mononucleotide of guanosine which is formed from GTP by the catalytic action of the enzyme guanyl cyclase and which, as a second messenger, is responsible for the intracellular mediation (usually an inhibitory control) of hormonal effects on various cellular processes, e.g., lipid metabolism, membrane transport, and cell proliferation.

IP₃ = inositol triphosphate - A second messenger molecule which is a phosphorylated alcohol (derived from a B vitamin) which binds with receptors on smooth endoplasmic reticulum to stimulate the release of calcium ions as a part of the amplification of a hormone's regulation of cellular enzymes.

calmodulin - A second messenger molecule which is a calcium-binding protein which regulates cellular metabolic processes, e.g., muscle-fiber contraction, by modifying the activity of specific calcium-sensitive enzymes.

Compare and Contrast:

2.  how lipid soluble hormones differ from water soluble hormones (in terms of accomplishing their effects)

 

Lipid Soluble Hormones

Water Soluble Hormones

1.  lipid soluble hormones diffuse through the target cell plasmalemma directly into the cytoplasm 2.  they bind to a cytoplasmic or nuclear receptor inside the target cell 3.  the hormone-receptor complex moves to DNA within the nucleus, binding to specific genetic blueprints for proteins 4.  the hormone-receptor complex initiates transcription of the specific gene(s); the mRNAs migrate to the cytoplasm, complex with ribosomes and translation, i.e., synthesis of the new protein occurs

1.  water soluble hormones cannot diffuse through the target cell plasmalemma 2.  they bind to a target cell surface receptor (membrane protein) 3.  hormone-receptor complex formation triggers membrane activity (G-protein activation, etc.) and, ultimately, activation of a membrane-bound enzyme which synthesizes a second messenger molecule within the cytoplasm 4.  the second messenger initiates a cascade such as the activation of enzyme catalyzed metabolic pathways

List and Describe:

16.  three examples of hormones which belong to each of the four chemical classes:  amine, peptide, protein, and steroid.

 

Hormone Chemical Class	Hormone Examples
Amine	PIH, thyroxine = tetraiodothyronine = T4 & triiodothyronine = T3, epinephrine = adrenalin, norepinephrine
Peptide	GHRH, GHIH = somatostatin, TRH, GnRH, CRH, oxytocin (OT), antidiuretic hormone (ADH) = vasopressin
Protein	human growth hormone (hGH), thyroid-stimulating hormone (TSH), follicle-stimulating hormone (FSH), luteinizing hormone (LH), prolactin (PRL), adrenocorticotropic hormone (ACTH), melanocyte stimulating hormone (MSH), calcitonin = thyrocalcitonin, parathyroid hormone = parathormone (PTH), glucagon, insulin, inhibin, relaxin
Steroid	aldosterone, cortisol, cortisone, hydrocortisone, estrogens, progesterone, androgens, e.g., testosterone,

Sketch and label:

3.  the action of a first messenger/second messenger system in controlling a target cell's response to hormone stimulation.

4.  the interaction of a steroid hormone, its cytoplasmic receptor, and subsequent gene activation.