A biologist wishes to take a useful gene found in pine trees and introduce it into some bacterial cells. Her experimental procedure is given below.

1. Use a restriction enzyme to cut a gene out of the pine tree DNA.
2. Use a restriction enzyme to cut open a plasmid.
3. Treat the plasmid with DNA ligase.
4. Mix the desired gene and plasmid together.
5. Introduce the plasmid into bacterial cells.
Which steps should be switched in the biologist's procedure?

A. 3 and 4
B. 1 and 3
C. 2 and 3
D. 4 and 5

option A

Explanation:

In carrying out these experimental procedure, the same restriction enzyme that is used to cut out the gene of interest should also be the same used for the cutting of the plasmid to generate sticky ends. Then the desired gene is inserted into the cut plasmid  then treatment with DNA ligase. Purified DNA ligase is utilized in gene cloning to join/ligate DNA molecules together forming a recombinant DNA. Thus, step 3 should be carried out after step 4.

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.