Answer:
Nucleus
the central and most important part of an object, movement, or group, forming the basis for its activity and growth.
Nucleolus
a small dense spherical structure in the nucleus of a cell during interphase.
Answer:
a. The operon is under positive control
a.) Loss of enzyme synthesis results from loss of regulatory R gene product which is regulated in the presence of Tis ophane for transcription. Absence of (Tis), transcription is positively controlled by regulatory Rprotein
b.) The proposed model reveals Tis / B complex prevents Tis enzymes from undergoing transcription through the RB operator by binding to the B region
the role of the R protein is
-decrease affinity of Tis / B complex to B region of RB
-bind to the R region on RB
- change the conformation of B region
- yield decreased affinity of Tis / B complex when R gene is lacking preventing transcription in the process
Effects of the RB mutations is that R protein will not bind to Tis / B complex to reduce transcription
Answer:
Topoisomerase
Explanation:
Topoisomerases are enzymes that produce changes in the topology of the DNA during replication, transcription, traduction, or reparation processes. They can cut one or both strands and in order to relieve torsional stresses in the supercoiled structure of DNA. With this, they help to maintain the chromosome's integrity. There are two types of topoisomerases: topoisomerase I (it cuts only one strand of DNA) and topoisomerase II (it is able to cut both strands of DNA).
Antibiotics are ineffective against viruses because viruses do not have cells. Viruses are infectious agents that live within the cells of other living things. Antibiotics work by breaking down the cell walls of bacteria or interfering with the bacteria's ability to repair its cell's DNA, according to How Stuff Works.
