Species a diverged from species b 60,000 years ago. on a particular gene, they have 15 nucleotide differences. how many nucleotide differences do you expect they will have in another 240,000 years (300,000 years since divergence)?

The given question says that b species diverged around 60,000 year ago from species a. Since the divergence, they have a nucleotide difference of 15 nucleotide.

We need to find out the nucleotide difference in another 240,000 year, which means a total of 300,000 year since divergence.

The nucleotide difference in 60,000 years = 15 nucleotide.

The nucleotide difference in 1 year =  nucleotide.

The nucleotide difference in 300,000 years = nucleotide.

The nucleotide difference in 300,000 years = 75 nucleotide.

Hence, after another 240,000 years or 300,000 years since divergence, the species and species b would show a difference of 75 nucleotide.

In another 240,000 years, there would be 60 nucleotide difference, as 15 of the nucleotide are already different in initial 60,000 years from the total of 75 nucleotide difference in 300,000 years. So, 60 (75-15) nucleotide difference would be observed in next 240,000 years.

step 1: initiation

initiation is the beginning of transcription. it occurs when the enzyme rna polymerase binds to a region of a gene called the promoter. this signals the dna to unwind so the enzyme can ‘‘read’’ the bases in one of the dna strands. the enzyme is now ready to make a strand of mrna with a complementary sequence of bases.

step 2: elongation

elongation is the addition of nucleotides to the mrna strand. rna polymerase reads the unwound dna strand and builds the mrna molecule, using complementary base pairs. there is a brief time during this process when the newly formed rna is bound to the unwound dna. during this process, an adenine (a) in the dna binds to an uracil (u) in the rna.

step 3: termination

termination is the ending of transcription, and occurs when rna polymerase crosses a stop (termination) sequence in the gene. the mrna strand is complete, and it detaches from dna.