Refer to this portion of a dichotomous key to answer the question.1. (a) has a single dorsal fin ® 5 (b) has a double dorsal fin ® 25. (a) has a small fin on back near tail ® 6 (b) has no fin on back near tail ® 76. (a) has barbs near the mouth ® catfish (b) does not have barbs near the mouth ® 107. (a) tail is asymmetrical ® sturgeon (b) tail is symmetrical ® 8what would the result be when identifying a fish with a single dorsal fin, no fin on its back near the tail, and a tail that is asymmetrical?

Sturgeon

Explanation:

The key has a series of dichotomies which are decisions that need to be made at different points and thus decide whether to go on one direction or the other until you reach one end of the key or the other. In this case, one end leads to Sturgeon and the other to Catfish. Both fish are similar in that they have a shark-like body. However, the sturgeon is the one that has a combination of the characters: A single dorsal fin, no fin on its back near the tail, and an asymmetrical tail (one lobe is longer than the other).

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.