There are two classes of snoRNPs involved in rRNA processing in nucleolus. 

The box H/ACA snoRNPs are involved in pseudouridylylation, and box C/D snoRNPs function in 2-O-methylations.

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#Unit 1. Molecules and their Interaction Relevant to Biology

Steroids derived from cholesterol.

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#Unit 1. Molecules and their Interaction Relevant to Biology

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#Unit 1. Molecules and their Interaction Relevant to Biology

β-Carotene is the precursor of vitamin A1.
Oxidation at C-15 converts retinol to the aldehyde, retinal, and further oxidation produces retinoic acid, a hormone that regulates gene expression. 

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Some other biologically active isoprenoid compounds or derivatives.

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#Unit 1. Molecules and their Interaction Relevant to Biology

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#Unit 1. Molecules and their Interaction Relevant to Biology

In most mammalian tissues, ubiquinone (also called coenzyme Q) has 10 isoprene units.

Dolichols of animals have 17 to 21 isoprene units (85 to 105 carbon atoms), bacterial dolichols have 11, and those of plants and fungi have 14 to 24.