Answer:
The correct answer is B high levels of lactose and high levels of cyclic AMP.
Explanation:
Lac operon contain 3 regulatory genes and 3 structural genes.In presence of lactose the repressor molecule that is encoded by Lac I gene cannot bound to the operator region.
Bacause the lactose interact with the repressor and change its conformation so that it cannot repress the expression of the structural genes of lac operon.
On the other hand cyclic AMP is a positive regulator of lac operon .The interaction of cyclic AMP with the promoter region of lac operon stimulates the binding of RNA polymerase in the promoter region to boost the expression of structural genes of lac operon such as Lac Z,Lac Y and Lac A.
Answer:
The lytic cycle.
Explanation:
<u>HIV is a retrovirus</u> that has a special enzyme called transcriptase reverse, which can synthesize DNA using RNA as a template. This replication system is particularly useful for the virus because the DNA synthesized from the RNA viral genome can be then integrated into the human chromosomes and stay inactive for years. This is called a lysogenic cycle and is characterized by a latency of the virus and an integration to the host DNA.
When there is a triggering event, <u>this latent virus can be excised from the human chromosome and start producing copies of itself using the host machinery.</u> <u>Then the virions are assembled and after that they lyse the host cell and release new infective units that can then infect neighboring cells. </u>This is called the lytic cycle of the virus and is the reproduction cycle that occurs when a person moves into the acquired immunodeficiency syndrome (AIDS) stage of HIV infection.
Answer:
Burning fossil fuels like coal and oil puts more carbon dioxide into our atmosphere. NASA has observed increases in the amount of carbon dioxide and some other greenhouse gases in our atmosphere. Too much of these greenhouse gases can cause Earth's atmosphere to trap more and more heat. This causes Earth to warm up.