Transcription and Translation

2.6.1. Compare the structure of RNA and DNA.
RNA has the ribose sugar while the DNA has the deoxyribose sugar in its structure. RNA is only one single strand while DNA has a double helix with two strands. Also, the thymine nucleotide of DNA is replaced by uracil in RNA (uracil, like thymine, attaches to adenine by hydrogen bonds).

2.6.2. Outline the DNA transcription in terms of the formation of an RNA strand complementary to the DNA strand by RNA polymerase.
The synthesis of RNA uses DNA as a template. First, the two strands of DNA are separated in a specific place. Then, with the help of RNA polymerase, RNA nucleotides attach to thier complimentary bases on one side of the exposed DNA strand. This creates a single strand of complimentary nucleotide bases. After this is done, the RNA molecule separates from the DNA.


2.6.3. Describe the genetic code in terms of codons composed of triplets of bases.

The genetic code for an amino acid is contained in DNA as a series of three nitrogenous bases. Each of these triplets (codons) code for a particular amino acid.


2.6.4. Explain the process of translation, leading to peptide linkage formation.
After transcriptions, the mRNA moves out of the nucleus into the cytoplasm where the mRNA attaches ro a ribosome. In the cytoplasm there are transfer RNA (tRNA) molecules. These molecules are composed of a short RNA molecule folded into a specific shape. Each tRNA molecule is shaped so that it bonds to a certain amino acid. Each tRNA moelcule also has an anticodon which compliments a certain mRNA codon. Once the mRNA attaches to a ribosome, it acts as a sort of conveyor belt. The tRNA molecules attach to the mRNA according to the complimentary nature of their bases. For example, a tRNA molecule with the anitcodon ACC will carry the amino acid tryptophan. This tRNA molecule will attach to the codon UGG on the mRNA because UGG compliments ACC. After two tRNA molecules are attached to the mRNA, they bond and the first tRNA molecule is released. Then another tRNA molecule connects to the mRNA etc, and the polypeptide is created.

2.6.5. Define the terms degenerate and universal as they relate to the genetic code.
Degenerate means that multiple triplets code for the same amino acid. For example, UUU and UUC both code for phenylalanine. Univeral refers to the fact that this genetic code occurs in all living organisms.

2.6.6. Explain the relationship between one gene and one polypeptide.
One gene corresponds to one polypeptide. It does not, however, always code for a protein, because many proteins consists of more than one polypetide