Which one of the following accurately describes the lac operon?

a. the repressor is freed from the operator when lactose is present.
b. rna polymerase transcribes the lac genes when lactose isn't present.
c. the repressor protein binds to the operator when lactose is present.
d. rna polymerase is prevented from transcribing the lac genes when lactose is present.

es the lac operon?

The correct option is A)  The repressor is freed from the operator when lactose is present.

Lac operon is an example of inducible operon in bacteria. It is used for the metabolism and transport of lactose. It consists of three structural gene, an operator, a promotor, and a regulatory element. Regulatory element produces active repressor, which binds to operator and turns off the operon.

In the presence of lactose, repressor becomes inactive and operon is turned on as transcription and translation of the structural genes takes place. Therefore, repressor can not bind to the operator in presence of lactose. Thus, repressor is freed from the operator when lactose is present.

Thus, the statement A) accurately describes Lac operon.

c.) polymerase chain reaction

- "unlike the original dna fingerprinting method, dna profiling does not use restriction enzymes to cut the dna. instead it uses the polymerase chain reaction (pcr)? to produce many copies of specific str sequences. pcr is an automated procedure that generates lots of copies of a specific sequence of dna."

the answer is z.

the human body has five levels of organization. level 1: cells. cells are the basic units of life and form the first level of organization. cells in the human body have specific functions. examples include nerve cells, blood cells, liver cells, and so on.