Table 1 shows mRNA codons and the amino acids they code for:
| 1st base | 2nd base: U | 2nd base: C | 2nd base: A | 2nd base: G | 3rd base |
|---|---|---|---|---|---|
| U | Phe | Ser | Tyr | Cys | U |
| U | Phe | Ser | Tyr | Cys | C |
| U | Leu | Ser | Stop | Stop | A |
| U | Leu | Ser | Stop | Trp | G |
| C | Leu | Pro | His | Arg | U |
| C | Leu | Pro | His | Arg | C |
| C | Leu | Pro | Gln | Arg | A |
| C | Leu | Pro | Gln | Arg | G |
| A | Ile | Thr | Asn | Ser | U |
| A | Ile | Thr | Asn | Ser | C |
| A | Ile | Thr | Lys | Arg | A |
| A | Met (Start) | Thr | Lys | Arg | G |
| G | Val | Ala | Asp | Gly | U |
| G | Val | Ala | Asp | Gly | C |
| G | Val | Ala | Glu | Gly | A |
| G | Val | Ala | Glu | Gly | G |
A molecular biologist investigated mutations affecting a specific beta-tubulin protein in yeast cells. This polypeptide is normally 445 amino acids long.
The genetic code is described as degenerate. Explain what is meant by this term and use a specific example from Table 1 to support your explanation.
Calculate the minimum number of bases in the coding region of the mRNA (excluding start and stop codons) required to synthesize this polypeptide.
Using Table 1, identify which of the following options represents a single-base substitution mutation in the DNA template strand that would cause a change from cysteine (Cys) to tryptophan (Trp):
