For each description, write whether it is diffusion, osmosis or active transport 1. If an animal cell is placed in distilled water, water will move into the cell, causing the cell to swell and burst.

2. A cell has a 50% sugar solution. It is in a beaker that has 10% sugar solution. Sugar moves from the cell to the beaker.

3. A cell is observed to have no sugar inside when it is placed into a concentrated sugar solution. After 10 minutes, there is sugar inside the cell. How did the sugar get into the cell?

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.