An Important Difference Between a Class I and Class II

question 54

Multiple Choice

An important difference between a class I and class II aminoacyl-tRNA synthetase is:

• A) The two classes proceed through different aminoacyl-AMP intermediates.
• B) Class I synthetases first attach the amino acid to the 2'-hydroxyl on ribose, whereas class II attach them to the 3'-hydroxyl.
• C) Class I synthetases attach amino acids to the 5'-end of the tRNA, whereas class II attach them to the 3'-end.
• D) The 5'-end of the tRNA molecule is phosphorylated only for those tRNAs recognized by class I synthetases.
• E) None are true.

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Definitions:

Insulation

Materials or substances used to prevent the transfer of heat, electricity, or sound from one area to another.

Lipids

A group of naturally occurring molecules that include fats, waxes, sterols, fat-soluble vitamins, and others, serving as a major energy source and structural components of cells.

Glycogen

A multibranched polysaccharide of glucose that serves as a form of energy storage in animals and fungi.

Carbohydrates

Organic compounds made up of carbon, hydrogen, and oxygen atoms, serving as a major energy source for the body.