Term
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Definition
| a steroid is a terpene. a terpene is a hydrocarbon derived from isoprene. |
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Term
| animal steroids include (3) |
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Definition
| sterols (cholesterol), bile acids, steroid hormones |
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Term
| 4 important parent ring structures |
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Definition
| cholestane, androstane, pregnane, estrane. |
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Term
| 5beta-dihydrotestosterone |
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Definition
| has no biological activity because it cannot interact with androgen receptor. active stereochemical form is 5alpha-dihydrotestosterone |
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Term
| cholesterol is synthesized where? (4) |
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Definition
| virtually all tissues, but especially in liver, adrenal cortex and gonads and placenta. |
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Term
| cholesterol synthesis requires (2) |
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Definition
| reducing equivalents (provided by NADPH) and energy derived from CoA and ATP |
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Term
| where in cell is cholesterol synthesized? |
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Definition
| cytoplasm - cytosol and er |
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Term
| HMG Coa synthase is ____ for cholesterol synthesis and ____ for ketoacid synthesis |
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Definition
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Term
| key rate limiting reaction in cholesterol synthesis |
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Definition
| HMG CoA reductase > makes mevalonate, which makes IPP which condenses to squalene, which cyclizes (hydroxylation) into lanosterol > cholesterol |
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Term
| how is HMG CoA reductase controlled |
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Definition
| predominantly at the expression level (regulation of mRNA abundance) and at the activity level (reversible phosphorylation) |
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Term
| precursor for steroid hormone synthesis |
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Definition
| cholesterol, except for vitamin D (whose precursor is 7-dehydrocholesterol) (need light to make vitamin D) |
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Term
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Definition
| cortisol and aldosterone and androstenedione |
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Term
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Definition
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Term
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Definition
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Term
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Definition
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Term
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Definition
| excreted as bile salts and bile acids |
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Term
| steroid hormone biosynthesis |
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Definition
| cholesterol from sER transported to mitochondria for side chain cleavage, makes pregnenolone, which returns to sER for further synthetic steps |
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Term
| steroid hormone biosynthesis in the gonads |
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Definition
| pregnenolone -> androgens, estrogens and progestins |
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Term
| steroid hormone biosynthesis in adrenal cortex |
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Definition
| pregnenolone goes back to mito for production of glucocorticoids and mineralocorticoids |
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Term
| steroid-secreting cells have abundant |
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Definition
| sER and tubular-vesicular cristae |
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Term
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Definition
| cyp, p450, cyp450. a large and diverse family of hemoproteins that often form electron transfer chains |
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Term
| most common reaction catalyzed by cyp |
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Definition
| monooxygenase reaction: R + O2 + NADPH = R-OH + H20 + NADP+ |
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Term
| p450scc / old names / regulation |
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Definition
| p450 side-chain cleavage enzyme. catalyzes cholesterol > progesterone. also referred to as CYP11A1 or 20-22 desmolase. regulated by LH in gonads and by ACTH in adrenal cortex |
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Term
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Definition
| steroid acute regulatory protein: facilitates transfer of hydrophobic cholesterol across the OMM to the IMM |
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Term
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Definition
| location of p250scc; this is where metabolism of cholesterol to pregnenolone occurs |
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Term
| lipoidal congenital adrenal hyperplasia |
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Definition
| mutations in StAR. no steroid hormones can be synthesized. all individuals are phenotypic females with salt-wasting crises. fatal if not treated during infancy |
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Term
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Definition
| lack of c7-reductase to make cholesterol from 7-dehydrocholesterol. retardation, ambiguous genitalia in males, abnormal face, low circulating cholesterol |
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Term
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Definition
| no c21-hydroxylase to make cortisol or aldosterone from progesterone. => abundance of androgens, > virilization of female infants, salt-wasting crises. can be treated with glucocorticoid and mineralocorticoid replacement. |
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Term
| 5alpha-reductase deficiency |
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Definition
| AR mutation in 5alpha-reductase-2. males are undervirilized but virilize at puberty. born with blind vaginal pouch, no mullerian derivatives, normal testes and wolffian derivatives. |
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Term
| biological actions of steroid hormones are determined by |
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Definition
| specificity and tissue localization or steroid hormone receptors |
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Term
| major course of vitamin d metabolites |
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Definition
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Term
| major source of retinoic acid |
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Definition
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Term
| major sources of progestins, estrogens, androgens |
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Definition
| p: ovary, placenta. e: ovary, placenta, testis. a: ovary, testis. |
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Term
| action of steroid hormone receptors requires (3) |
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Definition
| hsp70,90; coactivators (SRC); and a specific DNA binding element (zinc finger) = HIGHLY specific |
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Term
| complete androgen insensitivity / old name |
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Definition
| old name - testicular feminization. x-linked recessive disorder expressed in 46XY. mutation in androgen receptor gene. breasts, no pubic/axillary hair, primary amenorrhea, blind vaginal pouch. testes. wolffian derivatives absent, mullerian derivatives absent or vestigial. |
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Term
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Definition
| 2-5% increase in androgen receptor saturation; competitively inhibiting function of glucocorticoid receptor in muscle stops cortisol from breaking down muscle = higher net positive nitrogen balance |
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Term
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Definition
| 14-demethylation of lanosterol = cholesterol |
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Term
| ligand activated transcription factors |
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Definition
| steroid hormone receptors |
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