Two tRNA molecules occupy the P and A sites in a ribosome. The amino acids they carry are joined by ...

Two tRNA molecules occupy the P and A sites in a ribosome. The amino acids they carry are joined
  by a peptide bond. What is the very next event that occurs?
  A. The tRNA in the P site detaches and leaves the ribosome.
  B. A third tRNA enters the ribosome.
  C. The ribosome moves one codon down the mRNA.
  D. The large subunit leaves the ribosome.
  E. A new amino acid is joined to the tRNA in the P site.

Question 2

The shape of a protein is ultimately determined by
  A. the interaction of R groups.
  B. interaction with other polypeptide chains.
  C. the amino acid sequence.
  D. bonds formed with other proteins.
  E. none of these.