In E. coli, three structural genes (A, D, and E) encode enzymes A, D, and E, respectively. Sequence O is an operator. The sequences are in the order O- A- D- E on the chromosome. The three enzymes encoded by A, D, and E catalyze the biosynthesis of valine. Mutations at the A, D, E, and O were isolated to study the production of enzymes A, D, and E when cellular levels of valine were low (T. Ramakrishnan and E. A. Adelberg. 1965. Journal of Bacteriology 89:654-660). Amounts of the enzymes produced by partial-diploid E. coli with various combinations of mutations are shown in the following table. Amount of enz produced Genotype E D E* D* A* O*/E* D* 1. 2,40 2.00 A* O* E* D* A* O"/E* D* 2. 35.80 38.60 A* O* E* D A* O I 3. E* D* A" O* 1.80 1.00 E* D* A O / 4. 35.30 38.00 E* D A* O* E D* A* O / 5. 2.38 38.00 E* D A* O*
Bacterial Genomics
The study of the morphological, physiological, and evolutionary aspects of the bacterial genome is referred to as bacterial genomics. This subdisciplinary field aids in understanding how genes are assembled into genomes. Further, bacterial or microbial genomics has helped researchers in understanding the pathogenicity of bacteria and other microbes.
Transformation Experiment in Bacteria
In the discovery of genetic material, the experiment conducted by Frederick Griffith on Streptococcus pneumonia proved to be a stepping stone.
Plasmids and Vectors
The DNA molecule that exists in a circular shape and is smaller in size which is capable of its replication is called Plasmids. In other words, it is called extra-chromosomal plasmid DNA. Vectors are the molecule which is capable of carrying genetic material which can be transferred into another cell and further carry out replication and expression. Plasmids can act as vectors.
Is the regulator protein that binds to the operator of this operon a repressor (negative control) or an activator (positive control)? Explain your reasoning.
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