Catalysts are added to a reaction to decrease the activation energy. This will allow for reactants to easily overcome the energy barrier (activation energy) and carry out the reaction; therefore, the reaction will happen quicker and the rate of reaction will increase. Recall that the rate constant quantifies the rate of a reaction. Since rate of reaction and rate constant are directly proportional, addition of catalyst will lower the activation energy, increase the rate of reaction, and, subsequently, increase the rate constant.

It’s important to remember that catalysts only alter the rate of a reaction (speeds up the reaction). They have no effect on thermodynamics/equilibrium (the amount of products produced).

The speed of a reaction is increased when the amount of reactants reaching the activation energy (energy barrier) is increased. This can be done via two ways: increasing temperature or adding a catalyst. Increasing temperature will add kinetic energy to the reactant and increase the amount of reactants reaching the energy barrier. Adding a catalyst will decrease the activation energy and, subsequently, increase the amount of reactants reaching the energy barrier.

Since the temperature is kept relatively constant in the human body (due to homeostasis), the most common way human body increases the speed of a reaction is by using catalysts. Biological catalysts are called enzymes and they are usually named with the suffix -ase. The only molecule that is an enzyme in this question is DNAase, which catalyzes the hydrolysis of phosphodiester bonds in the backbone of DNA.

ATP provides energy for active reactions but it cannot speed up the reaction. Histones are proteins found in nucleus that are involved in DNA packaging. They are irrelevant to this question.

Catalysts are chemicals that function to speed up a reaction. They do not, however, change the amount of products produced (the equilibrium of the reaction). They just make it so that the equilibrium is reached at a faster rate. The main way catalysts decrease reaction rate is by lowering the activation energy. This is the energy peak required to create transition states (molecules that are in between reactants and products). Once past this peak, the transition states convert into the products. Catalysts lower this peak so that it is easier to create transition states.

As mentioned, equilibrium constant will not change because catalysts do not alter the equilibrium of the reaction. Enthalpy (change in heat) of the reaction will also remain constant because it is not altered by the catalyst.

An adiabatic reaction is characterized as a reaction that neither gains nor loses net heat. This means that the process of converting the reactants to products does not alter the heat in the system (reaction) or the surroundings; therefore, both the heat inside and outside the system will be constant.

Enzymes are biological catalysts that speed up many reactions essential for the human body. Their chemistry is the same as catalysts. They speed up reactions by lowering the activation energy of reactions. This allows reactions to easily overcome the energy barrier and create the necessary products from reactants.

Competitive inhibition decreases enzyme activity by binding to the active site of the enzyme. Recall that active sites are sites on enzymes where the substrates bind. Upon binding to the enzyme, the substrates undergo changes that facilitate and speed up the chemical reaction. A competitive inhibitor binds to this active site and prevents the substrate from binding. With no binding, the substrate will not undergo the necessary changes and, subsequently, the chemical reaction. A key characterisitic of competitive inhibitors is that the bond between the inhibitor and the active site is reversible. This means that the chemical bonds involved here are weak, reversible noncovalent bonds such as hydrogen bonds and van der Waals forces. Covalent bonds are very strong and are usually found in irreversible interactions.

Allosteric inhibitors are molecules that bind to enzymes at their allosteric site(s). In this way, the allosteric inhibiton is very similar to, and is a subset of, another type of enzyme inhibition, noncompetitive inhibition.

Recall that competitive inhibition can be overcome by increasing substrate concentration. Competitive inhibitors alter the Michaelis constant, , but maintain the  (maximum reaction rate). Inhibitors act to decrease the reaction rate. To figure out the effect of competitive inhibitors on the Michaelis constant, we need to look at the Michaelis-Menten equation.

where  is reaction rate,  is maximum reaction rate,  is substrate concentration, and  is the Michaelis constant. Since reaction rate is inversely proportional to the , competitive inhibitors will increase  and, thereby, decrease reaction rate.

To answer this question we need to first figure out the equation for slope and x-intercept of Lineweaver-Burk plot. The Linweaver-Burk plot is a graphical way to plot the Michaelis-Menten equation. It is defined as the reciprocal of Michaelis-Menten equation. Michaelis-Menten equation is as follows.

where  is reaction rate,  is maximum reaction rate,  is substrate concentration, and  is the Michaelis constant. Taking the reciprocal of this gives us

The slope, therefore, is . The x-intercept can be found by plugging in zero for the Y value (the reaction rate, ). The x-intercept is .

 The question states that the slope is  and the x-intercept is . Using the equation for x-intercept we can solve for .

Using the equation for slope we can solve for 

Recall that the addition of a noncompetitive inhibitor alters the  but not the ; therefore,  is still  after the addition of noncompetitive inhibitior.

Note that if we were asked to solve for the , we would have had to use the new slope () and the same  value ().

Noncompetitive inhibitors bind to enzymes and prevent the formation of the enzyme-substrate complex. These inhibitors bind to a location other than the active site. Upon binding, the inhibitors alter the conformation of the active site and prevent the binding of substrate. They form covalent bonds with the enzyme; therefore, these are irreversible inhibitors and are hard to remove.  and  are altered by both types of inhibitors (competitive and noncompetitive). Competitive inhibitors alter the  whereas the noncompetitive inhibitors alter the .

This implies that competitive inhibition can be overcome by increasing substrate concentration whereas noncompetitive inhibition cannot. Molecularly this makes sense. Competitive inhibitors bind reversibly to the active site and prevent binding of substrate. If we were to drastically increase its concentration, substrate will compete with and remove the competitive inhibitor from the active site. Noncompetitive inhibitors, on the other hand, alter the conformation of the active site, making it hard for substrates to bind to the active site; therefore, the substrate will not be able bind, regardless of the substrate concentration.  

Inhibitors are molecules that prevent the action of catalysts. They bind to catalysts and prevent substrate binding, thereby halting the catalytic action. Since catalysts increase the speed of a reaction, addition of an inhibitor will lower the speed of the reaction. This does not mean that the reaction will stop proceeding; it simple means that it will take longer for the reaction to complete (reach equilibrium).

Remember that a catalyst speeds up both the forward and the reverse reaction; therefore, inhibitors will slow down both reactions. As mentioned, inhibitors will only slow down the reaction. The amount of products produced (equilibrium) will not change, although it will take longer for products to form.