After DNA is transcribed into RNA, the RNA goes through post-transcriptional modifications and is then sent out of the nucleus to the cytoplasm. From there, the mRNA is brought to the ribosomes, some located on the rough endoplasmic reticulum and some free-floating, in order to be translated into proteins. Proteins are then packaged and transported to their respective locations for usage.

The nucleolus is responsible for synthesizing and assembling ribosomal subunits. The nucleus houses DNA and is the site of transcription, but not translation. Mitochondria are essential for cellular respiration and ATP synthesis. Lysosomes digest cellular wastes and defective proteins.

Elongation continues until a stop codon occupies the A-site of the ribosome. The stop codon is a three-base signal present within the mRNA. There are three stop codons: UAG, UAA, and UGA.

There are three principle steps to translation. Initiation occurs when the ribosomes encounters the start codon, AUG, and recruits a methionine tRNA. Elongation of the polypeptide occurs as the ribosomes continues to recruit tRNA molecules and build the peptide chain. Termination occurs when the ribosome encounters a stop codon and releases the completed polypeptide.

Missense mutations are point mutations that cause a single amino acid in a protein to be changed. This may or may not affect the functionality of the protein. When one amino acid is replaced by another amino acid from the same class, such as replacing one polar amino acid with another, functionality is usually retained. When an amino acid from a different class is used, such as replacing an acidic amino acid with a basic amino acid, the protein folding may be affected and functionality may fail.

The other answers describe other types of mutations. Silent result in no change to the protein primary structure. Nonsense mutations cause early termination. Frameshift mutations shift the reading frame of the codon sequence, severely altering the protein composition.

The three steps for the elongation process of translation are codon recognition, peptide bond formation, and translocation. These steps essentially correspond to the different tRNA positions in the ribosome. tRNA enters and matches the codon of the mRNA strand. A peptide bond is then formed between the tRNA amino acid and the ribosomal amino acid chain. The empty tRNA and peptide strand then shift to make room for the next residue to enter to ribosome structure.

RNA spicing occurs in the nucleus as part of post-transcriptional modification. Introns are removed to generate a mature mRNA strand before translation can occur.

Transcription leads to the production of hnRNA (heterogeneous nuclear RNA), which primarily consists of pre-mRNA and must go through processing and modification to form mRNA and leave the nucleus.

The other three choices, mRNA (messenger RNA), tRNA (transfer RNA), and rRNA (ribosomal RNA), all play active roles in the process of translation. mRNA serves as the codon template. tRNA matches anticodons to mRNA and carries amino acids. rRNA forms a large part of the ribosome structure and plays a functional role as the site of translation.

Translation is the process of making a polypeptide chain from an mRNA template. No new molecules of RNA or DNA are synthesized during this process. tRNA is used to bring amino acids to the ribosome, binding an anticodon to the exposed codon of mRNA. The amino acid is then released from the tRNA and added to the growing chain of amino acids attached to the ribosome. When the ribosome reaches a stop codon, it releases the mRNA strand and amino acid sequence. The amino acid sequence is the final result of translation, and is known as a polypeptide.

Polypeptides can then undergo folding to become functional proteins. All enzymes are proteins, but not all proteins go on to become enzymes; some serve other functions.

The mRNA strand is translated into a protein using triplets, or three nucleotides. Each triplet is called a codon. Messenger or mRNA codons bind to complementary anti-codons on tRNA molecules, which carry the corresponding amino acids.

The wobble position refers to the ability of the third position nucleotide of the codon and first position nucleotide of the anticodon tRNA sequence (when reading in a 5’ to 3’ direction) to exhibit non-standard base pairing. This allows fewer tRNA molecules to exist because a tRNA molecule is able to bind to more than one codon, which increases efficiency.

During the elongation stage of translation, GTP is used to provide the energy to translocate a tRNA molecule from the A-site to the P-site. GTP is also required to move the ribosome down the mRNA strand to the next codon.

In translation, stop codons within the mRNA strand signal the termination of the protein sequence to be translated. The stop codon nucleotide triplets are UAG, UGA, and UAA. Stop codons do not bind to an anticodon within a tRNA molecule, but rather to release factors. Release factors are proteins that recognize stop codons. The binding of release factors triggers the disassembly of the translational apparatus.