9 Imagine a species that uses a different genetic code in wh

9) Imagine a species that uses a different genetic code, in which codons are only 2 base pairs long. How many amino acids could that species have? Remember that it needs a start codon and a stop codon. Design a genetic code for this organism. Make a drawing (schematic) that depicts transcription and translation, including a 6 bp long double stranded DNA molecule and at least 8 labels.

Solution

Dear student theee a group of separate questionz posted separately. I would try to answer more than one.

11.

Silent mutation: Type of mutation in which mutation does not significantly alter the phenotype of an organism.

Codon GUA codes for valine. If A in this codon is replaced by G, the resulting codon will be GUG. This codon will still code for valine and it will not cause any change in the phenotype or protien coded. This type of mutati9n is called as silent mutation.

Substitution mutation: Mutation in which there occurs substitution of one base for another such as switching an A to a G. Such a substitution could change a codon to one that encodes a different amino acid and cause a small change in the protein produced.

For example in beta chain of normal haemoglobin, sequence CTC is transcibed into codon GAG which codes for glutamic acid. Due to susbtitution of T with A in DNA, sequence CTC is changed into CAC which is transcribed into Codon GUG which codes for Valine. This results in the production of faulty haemoglobin molecule called as sickle cell haemoglobin.

Non sense mutation: A nonsense mutation is a point mutation in a sequence of DNA that results in a premature stop codon, or a nonsense codon in the transcribed mRNA. The altered DNA sequence prematurely signals the cell to stop building a protein. This type of mutation results in a shortened protein that may function improperly.

Suppose a DNA sequence TTCTTTCTC will be transcribed into codon AAG AAA and GAG. These three codons will code for amino acid Lysine , lysine and glutamic acid. Due to susbtitution of C at the 7th position with A it will change DNA sequence into TTCTTTATC, that will be transcribed into codon AAG, AAA and UAG. Since UAG is a stop codon it will tetminate poplypeptide chain synthesis after coding two amino acids.

Deletion: type of mutation in which a base or small segment of DNA is deleted or lost.