Which of the following statements are true?
1) All organisms use the same codons as STOP codons during the process of translation.
2) Exons are sequences found on the rRNA molecules that are expressed during translation.
3) The genomes of some organisms code for non-standard amino acids, amino acids that are not one of the 20 amino acids associated with animal translation.
4) Reverse transcriptase uses RNA as a template to produce a molecule of cDNA.
5) The start codon of an mRNA molecule codes for the same amino acid in all organisms.