AP BIOLOGY

Detailed explanation-1: -The mRNA is then pulled through the ribosome; as its codons encounter the ribosome’s active site, the mRNA nucleotide sequence is translated into an amino acid sequence using the tRNAs as adaptors to add each amino acid in the correct sequence to the end of the growing polypeptide chain.

Detailed explanation-2: -During translation, ribosomal subunits assemble together like a sandwich on the strand of mRNA, where they proceed to attract tRNA molecules tethered to amino acids (circles). A long chain of amino acids emerges as the ribosome decodes the mRNA sequence into a polypeptide, or a new protein.

Detailed explanation-3: -During transcription, the enzyme RNA polymerase (green) uses DNA as a template to produce a pre-mRNA transcript (pink). The pre-mRNA is processed to form a mature mRNA molecule that can be translated to build the protein molecule (polypeptide) encoded by the original gene.

Detailed explanation-4: -1) The anticodon of an incoming tRNA pairs with the mRNA codon exposed in the A site. 2) A peptide bond is formed between the new amino acid (in the A site) and the previously-added amino acid (in the P site), transferring the polypeptide from the P site to the A site. 3) The ribosome moves one codon down on the mRNA.

Detailed explanation-5: -A gene sequence is converted into a polypeptide sequence via two processes: Transcription – making an mRNA transcript based on a DNA template (occurs within the nucleus) Translation – using the instructions of the mRNA transcript to link amino acids together (occurs at the ribosome)