Answer: the amino acid phenylalanine.
- A the amino acid proline
- B the amino acid phenylalanine
- C a chain-terminating signal
- D the amino acid methionine
Correct answer: B. the amino acid phenylalanine
Explanation: Using a synthetic poly-U mRNA, Nirenberg and Matthaei obtained a polyphenylalanine chain, establishing that UUU codes for phenylalanine.
Helicase unwinds the double helix at the replication fork; one new strand (leading) is synthesised continuously toward the fork, while the other (lagging) must be made in short, separate Okazaki fragments because DNA polymerase only adds nucleotides 5'→3'.
Concept context
DNA structure, replication, transcription, translation, the genetic code, and gene regulation (lac operon). The single most important chapter for NEET molecular biology.