The diagrams show different stages of cell division in the somatic cells of a plant. the stages are not shown in order.

First would be prophase, where the nucleus is dissolved. Then comes metaphase, where the chromatin condenses into chromosomes and the chromosomes are lined up in the center. Next is anaphase, in which spindle fibers attach to the telomeres of the chromosomes and separated to opposite ends of the cell. Finally, comes Telophase and Cytokinesis, in which the entire cell pinches apart and two new nuclei are formed around the duplicated chromosomes.

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.