Question

1. A researcher has developed an experiment to measure the activity of an important liver enzyme. She adds the substrate for the enzymatic reaction to the dish of cells, then measures the appearance of the reaction products. The results are graphed as the amount of product on the y axis versus time on the x axis. The researcher noted four sections of the graph. For a short period of time, no products appeared (section A). In section B, the reaction rate was quite rapid (the slope of the line was steep). After some time, the reaction slowed down considerably (section C), although products continued to appear (the line was not flat). Still later, the reaction resumed its original rapid rate (section D). Draw the graph, and propose a model to explain the molecular events underlying this interesting reaction profile.

1. What do you think is meant by enzyme saturation? Why is it that when an enzyme is saturated, the only way to increase the productivity of a reaction is to add more enzyme?

1. Hemoglobin is a protein found in red blood cells that binds to oxygen which in turn carry oxygen through the circulatory systems to cells in the body. Hemoglobin has four sites or heme groups where oxygen binds. Interestingly, when one oxygen molecule binds to a single heme group, all the other heme groups become more receptive to oxygen. How might you explain this given some of the themes we’ve discussed in this class?

1. Much of the nucleotide sequences of DNA is non-coding sequences (they don’t code for a protein or RNA molecule). Many biologists feel these non-coding sequences might function more as a structural component for the DNA molecule. Evidence of this comes from the DNA of thermophilic (heat-loving) bacteria, which tend to have a greater percentage of C-G pairing in their non-coding sequences in comparison to non-thermophilic bacteria. Can you identify the relationship between G-C abundance and a structural function in thermophilic bacterium?

Answer 1

Enzymatic saturation is a particular point where the reaction rate becomes maximum without any further increase at that specific point of substrate concentration.

On addition of substrate in the above experiment at first the rate of reaction get increased upto a point when all enzymes sites are occupied.The higher the substrate concentration the greater will be rate of enzyme reaction upto a point where all enzyme active sites are utilised to catalyse reaction.Finally they reaches a saturation point.Here the reaction starts proceeding at its maximum rate.When all the enzymes get substrates each,the reaction rate plateaus .

Beyond the saturation point the increasing substrate concentration will not increase rate of reaction since all the enzymes are working at its maximum rate and it need to be reused to act on additional substrate.To increase reaction rate increase the enzymeconcentration. Hence only way to increase rate of reaction is addition of enzymes.

Haemoglobin containing cells include A9 dopaminergic neurones present in lungs , hepatocytes etc.Haemoglobin contain 4 globular protein subunits where each contain a protein chain connected with protein prosthetic heme group.

Thermophilic bacterias are hyperthermophilic as it lives at very hot environment.The DNA polymerase gets incubated even without loss of activity and also can withstand temperature of 100 degree Celsius.The percentage of GC of thermophilic bacterium at its average is 48.41.The variation in GC concentration causes substitutional assymetry.

Inevede in Contents a la High L- effect YuuN on Recetion ensy Substrate concentration