You are studying a new strain of E. coli that can utilize the disaccharide melibiose very efficiently. You find that utilization depends on the enzyme melibiase, which is encoded by the gene Mel1. Mel1 is not expressed unless melibiose is present in the growth medium. Next you isolate a mutation, designated MelB–, which gives uninducible melibiase activity. Mapping experiments show that MelB– is linked to Mel1. Using an F' factor that carries the chromosomal region surrounding Mel1, you perform the following genetic tests:

                      

Describe the basic genetic properties of the MelB– mutation?

#Question id: 10277

#Unit 6. System Physiology – Plant

Each of the nine glycolytic intermediates between glucose and pyruvate is phosphorylated. The phosphoryl groups seem to have many functions such as,

a) The plasma membrane generally lacks transporters for phosphorylated sugars, the phosphorylated glycolytic intermediates cannot leave the cell

b) After the initial phosphorylation, further energy is necessary to retain phosphorylated intermediates in the cell, despite the large difference in their intracellular and extracellular concentrations

c) Phosphoryl groups are essential components in the enzymatic conservation of metabolic energy, Energy released in the breakage of phosphoanhydride bonds is partially conserved in the formation of phosphate esters such as glucose 6-phosphate

d) Binding energy resulting from the binding of phosphate groups to the active sites of enzymes lowers the activation energy and increases the specificity of the enzymatic reactions

which of the following functions shows Importance of Phosphorylated Intermediates?

#Question id: 5315

#Unit 11. Evolution and Behavior

In humans, the embryonic and fetal forms of hemoglobin have a higher affinity for oxygen than that of adults. Why is this the case?

#Question id: 11311

#Unit 1. Molecules and their Interaction Relevant to Biology

How many possible stereoisomers can be possible with D-fructose?

#Question id: 4454

#Unit 3. Fundamental Processes

Correct series of sigma regions,

#Question id: 2937

#Unit 2. Cellular Organization

Separase initiates sister chromatid segregation at anaphase by cleaving: