5 min read•june 18, 2024
Jed Quiaoit
Caroline Koffke
Jed Quiaoit
Caroline Koffke
The highly complex organization of living systems refers to the many different processes that occur within cells and organisms, such as , , and . These processes involve the participation of many different , including , which catalyze and are essential for maintaining the proper functioning of the cell or organism.
Enzyme plays an important role in the highly complex organization of living systems by allowing the cell to perform its functions more efficiently. For example, enzymes catalyze the breakdown of nutrients to generate energy, the synthesis of such as , , and , and the transfer of information between molecules. 🧬
This efficiency allows living systems to perform the wide range of chemical reactions necessary to sustain life while maintaining a relatively steady state, through constant input of energy and the exchange of macromolecules.
The constant input of energy is necessary to keep the enzymes functioning and also to power the chemical reactions that enzymes catalyze. Enzymes can be thought of as molecular machines that need energy to work properly, and their activity is usually coupled with energy-consuming reactions such as the transfer of electrons, proton, or . 🤖
The exchange of macromolecules is another important aspect of the highly complex organization of living systems. Macromolecules, such as proteins and , are constantly being synthesized, degraded, and recycled. Enzymes play an important role in this process by catalyzing the synthesis and breakdown of these molecules.
The turnover of these molecules is crucial for maintaining the balance of the cell, the growth and the response to the environment!
Simply put, catalysis is the process by which a speeds up a chemical reaction. 🏃💨
Catalysts work by providing an alternative reaction pathway with a lower . In other words, catalysts can make a reaction proceed faster by providing an easier way for the to transform into . They can do this by:
Enzymes are biomolecules that catalyze chemical reactions in cells. Just like any other catalyst in other disciplines, they do this by lowering the activation energy (the amount of energy required for a reaction to proceed) of the reaction they catalyze. This allows the reaction to occur more quickly and efficiently.
Enzymes are specific for the reactions they catalyze and the substrates (remember: substrates = reactants) they act on. They do this by having a unique three-dimensional structure that allows them to bind to the substrates in a specific way, a process called . This binding forms an intermediate complex called the , which is more reactive than the substrate alone. 🧊
As the enzyme catalyzes the reaction, the substrate is converted into products, which then dissociate from the enzyme, leaving it free to bind to another substrate molecule. Enzymes can be reused several times in this way.
The rate of an enzyme-catalyzed reaction is affected by several factors, including the concentration of substrate, the presence of or , and the temperature and pH of the environment.
An increase in substrate concentration can lead to an increase in the rate of an enzyme-catalyzed reaction, up to a certain point, after which the rate levels off. This is known as the .
Inhibitors are molecules that bind to enzymes and decrease the rate of reaction. They can do this by binding to the active site of the enzyme and preventing substrate binding, or by altering the shape of the enzyme so it cannot bind to the substrate.
Activators are molecules that bind to enzymes and increase the rate of reaction. They can do this by increasing the stability of the enzyme-substrate complex, making it more likely that the substrate will bind to the enzyme.
The temperature and pH of the environment also affect enzyme activity. Most enzymes have an and pH at which they function best. At temperatures or pHs outside this range, the enzyme may become denatured, or lose its shape, and can no longer function.
A few substances act to inhibit or activate the processes of enzymes. While there are many environmental factors that can alter an enzyme’s ability to function, explained next, there are also certain molecules that can act to change the process as well. A chart of these molecules is shown below. 😡
A scientist wants to study the effect of pH on the activity of an enzyme called "Protein X." He prepares a solution of the enzyme at a concentration of 0.1 mg/mL and adds it to a reaction mixture containing the substrate for the enzyme. He then measures the rate of the reaction at different pH levels. The table below shows his results.
pH | Reaction Rate (mM/min) |
7.0 | 0.10 |
7.5 | 0.15 |
8.0 | 0.20 |
8.5 | 0.15 |
9.0 | 0.10 |
Based on these results, answer the following questions:
** Check out the AP Bio Unit 3 Replays or watch the 2021 Unit 3 Cram**