Below are dna sequences for two species. identify how closely the species are related and what proves the relationship. species a tagcttagggacgg species b taccttagggacgg a)the species are not closely related because their nucleotide sequences are almost identical. b) the species are closely related because their nucleotide sequences are nearly identical. c) the species are not closely related because there are many differences between their nucleotide sequences. d) the species are closely related because they have the same number of nucleotides in their nucleotide sequences.

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.

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