Term
| True or False. Cholesterol from diet is packaged into VLDL along with TAG in the liver. |
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Definition
| False. Cholesterol that is synthesized in the liver is packaged into VLDL along with TAG. Cholesterol from diet and TAG are packaged into chylomicrons in intestinal cells. |
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Term
| Identify the steroid hormones that derive from cholesterol |
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Definition
| progesterone, 17 B-estradiol, testosterone, cortisol, aldosterone, 1,25-dihydroxy-vitamin D3, dehydroepiandroesterone |
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Term
| Identify the vitamin that derives from a cholesterol-like precursor |
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Definition
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Term
| Identify the mechanisms by which the activity of HMG-CoA reductase (rate-limiting step enzyme in cholesterol biosynthesis) is regulated |
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Definition
-regulated by the concentration of mevalonate, cholesterol, AMP, and sterols
-sterols inhibit enzyme mRNA production -> decreased enzyme synthesis
-mevalonate produces nonsterol metabolites that inhibit translation
-high levels of products, mevalonate and cholesterol, lead to enzyme degradation
-AMP-activated protein kinase phosphorylates HMG-CoA reductase and inhibits it ; cholesterol synthesis ceases when ATP is low
- high cholesterol levels inhibits the enzyme by decreasing transcription of genes for the enzyme |
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Term
| Predict the effects of elevated cholesterol on the activity of HMG-CoA reductase |
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Definition
| -decreases transcription of the enzyme and increases degradation |
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Term
| Describe the major functions of bile acids |
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Definition
-metabolize lipids
-only way for cholesterol to be excreted |
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Term
| Predict the effects of increased cholesterol on the activity of 7-alpha-hydroxylase |
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Definition
| excess cholesterol activates 7-alpha-hydroxylase which results in increased bile acid synthesis/utilization |
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Term
| Predict the effects of increased cholesterol on the activity of ACAT |
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Definition
| Excess cholesterol activates ACAT which results in increased cholesterol storage |
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