There Are 61 MRNA Codons That Specify an Amino Acid

question 30

Multiple Choice

There are 61 mRNA codons that specify an amino acid, but only 45 tRNAs. This is best explained by the fact that ________.

• A) some tRNAs have anticodons that recognize 4 or more different codons
• B) the rules for base pairing between the third base of a codon and tRNA are flexible
• C) many codons are never used, so the tRNAs that recognize them are dispensable
• D) the DNA codes for all 61 tRNAs, but some are then destroyed
• E) competitive exclusion forces some tRNAs to be destroyed by nucleases

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Definitions:

Afferent Fibres

Afferent fibres are nerve fibers that carry sensory information from the body's periphery towards the central nervous system.

Sleep Spindles

Sudden surges of oscillatory brain activity observed during stage 2 of non-REM sleep, associated with learning and memory consolidation.

Stage 2 Sleep

A phase of sleep characterized by the presence of sleep spindles and K-complexes, indicating a deeper sleep than stage 1.

REM Sleep

A phase of sleep characterized by rapid eye movement, dreaming, and increased brain activity similar to the waking state.