What animals such as jellyfish or worms may be preserved as carbonaceous films in black shales.?

mollusks.

Explanation:

Mollusks and other soft-bodied animals as jellyfish or worms may be preserved as carbonaceous films in black shales.

These animals generally have a body divided into: head, foot and visceral mass. The sense organs are found in the head. The foot is responsible for the movements and, in some animals, like the octopus, it can be replaced by the tentacles. The visceral mass is where all the organs are located.

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.