18. Summary
Transcription begins in the cell nucleus when RNA polymerase breaks apart the
DNA strand and then makes mRNA strand. After the RNA polymerase breaks apart the
strand, it will reform the hydrogen bonds. As the RNA polymerase is going through the
strand, it will synthesis the top strand. Thymine is now replaced with uracil. So now,
Adenine and uracil pair together and guanine and cytosine pair together. Once the
RNA polymerase reaches the termination sequence it breaks off and the mRNA strand
goes out of the nucleus through a nuclear pore. That will end the process of
transcription. To begin translation in the cytoplasm, the bottom strand of the original
DNA strand will be put into groups of three called codons. The first group is called the
start codon and will always be the letters TGA and the start codon is the last group of
three which can be paired in three different ways. A ribosome with a large subunit and
a small subunit will come and bring a tRNA molecule which will bring the anti codons
down to the strand with an amino acid. As the third tRNA molecule comes, the one in
the front will fall off leaving only the amino acid. As this process continues, once it
reaches the stop codon, there will not be a tRNA molecule for the stop codon, it will
just stop and what will be left will be the polypeptide bond. The final protein in its
tertiary structure is the single polypeptide chain also known as the backbone with one
or more protein secondary structures.