Codon bias can be seen in a genome i. What causes the higher mutation rate from
ID: 132312 • Letter: C
Question
Codon bias can be seen in a genome i. What causes the higher mutation rate from G to A and C to T? ii. What causes the higher frequency of select tBNAs within a cell? ii. Why are some codons less prone to translation errors? Gene trafficking has occurred multiple times in evolutionary history, including the transfer of multiple genes required for the large, quaternary-structured RUBISCO from the plastids to the plant nucleus. From an evolutionary standpoint, what BENEFIT is derived from the plant from having to produce some of the individual proteins for this important plant enzyme? Sulfate must be reduced to sulfite before it can be metabolized to produce sulfur-containing chemicals (such as the amino acid cysteine). What evolutionary benefit would be provided to the plastid for being the sole site for sulfate reduction in plants? i. ii.Explanation / Answer
1 (i) A transition mutation is the replacement of a purine base by the other purine base (G replaced by A) and pyrimidine base (C replaced by T). Transition mutations are much more common in most of the species. Reasons are
(ii) In order to insure survival of cells accurate and efficient translation machinery is required. The information encoded in mRNA sequences has to be translated into proteins. To ensure accuracy several mechanisms has been evolved include substrate recognition and proofreading steps. Therefore there is high selection rate of tRNAs within the cell.
(iii) Some codons are less prone to translational error because they change the identity of encoded protein and thus terminate translation. Therefore the error is not carried forward in the genome.
2.(ii) Since the plastids are the sole site for sulfate reduction in plants therefore with evolution these plastids have some how