Question

Q1/ Some bacteria can live in very extreme conditions. How can they survive?

Q2/ How can the process of competitive inhibition be deactivated?

Answer 1

1.There are organisms that can survive in harsh extreme conditions. These are known as extremophiles. They can be categorized as :

Acidophiles: Can live in low pH conditions (acidic). These organisms can survive at a pH range of 0-5. They have adapted themselves to survive in such conditions by either strengthening their cell membranes (produce biofilsm) which provides protection or by regulating the internal pH by pumping out protons from the intracellular space and hence controlling the pH of the cytoplasm near to neutral.

Alkaliphile: Can survive in high pH by regulating their internal pH. Moreover, they express enzymes which can withstand such high pH.

Psychrophiles: are organisms that can thrive in low temperatures and are usually found in deep sea/ocean. To adapt in such extreme conditions these type of organisms have the ability to develop glycerol or antifreeze proteins which can lower the freezing point of water.

Thermophiles: are organisms that can flourish at very high temperatures. These thermophiles can express heat resistant protein and thus consists of enzymes that are very well adapted for heat or high temperature.

In conclusion, the extremophiles have adapted to the extreme conditions mainly through the expression of proteins that are required to therive in such conditions.

2.  Competitive inhibition: In order to regulate the enzymes cells either promote or inhibit them. Competitive inhibition involves the inhibition of enzyme through various substrate analogs (inhibitors) that can bind to the active site of the enzyme and inhibits the formation of enzyme-substrate complex and ceases the reaction. The inhibitor molecule competes with the substrate to inhibit the reaction.

During the competitive inhibition the Km (substrate concentration at which the reaction rate is half of Vmax) of the  reaction increases while there is no change in the Vmax or the velocity of the reaction.

here in the figure, the comparison between the enzyme kinetics of an inhibited and normal enzyme is shown where it can be observed that the competitively inhibited enzyme has a higher Km. the competitive inhibitor does not change the Vmax as it cannot change the catalysis in the enzyme substrate complex as it binds only to the enzyme and not the ES complex.

This inhibition can be reversed by increasing the concentration of substrate which results in the increased probability of substrates to bind with the enzyme and diminish the effect of the inhibitor.