Enzymes: Study with Video Lessons, Practice Problems & Examples

Enzymes are biological catalysts that accelerate chemical reactions without being consumed. They convert substrates, the reactants in enzymatic reactions, into products efficiently. Key functions of enzymes include protein synthesis, DNA replication, and food digestion. Environmental factors like temperature, pH, and reactant concentration significantly influence enzyme activity, with extreme conditions potentially leading to denaturation, which impairs function. Understanding these concepts is crucial for grasping metabolic processes and maintaining homeostasis in living organisms.

Enzymes

In this video, we're going to begin our lesson on enzymes. An enzyme is defined as a molecule that catalyzes or speeds up a chemical reaction and is able to speed up the chemical reaction without being consumed by the chemical reaction, which means that the enzyme is not going to be altered by the end of the reaction. If we take a look at our image down below, notice that we're comparing a non-enzymatic reaction that has no enzyme to an enzymatic reaction that does have an enzyme. Notice on the left over here, we're showing you some reactants, the starting material or the ingredients for a reaction being converted into the products over here on the right, but notice that no enzyme is involved. And typically, when there's no enzyme involved, then the reaction is going to occur really, really slow, too slow for life to be able to rely on reactions that do not have enzymes.

Notice that over here on the right, we're showing you the same reaction. This time, notice that an enzyme is present, and the enzyme is represented by this structure that you see down below. The enzyme's job, its function, is to catalyze or speed up the chemical reaction so that it occurs much faster. You can see that the same reaction is able to occur at a much faster rate thanks to the enzyme.

Enzymes are all about catalyzing or speeding up chemical reactions. It's also important to note that the term "substrates" refers to the reactants of a chemical reaction that is catalyzed by an enzyme. If an enzyme is involved, then the reactants are referred to specifically as substrates. So, you can see that the substrates are pretty much the same thing as the reactants, and really the only difference is that "substrates" implies that an enzyme is involved, whereas "reactants" does not necessarily imply that an enzyme is involved. This here concludes our brief introduction to enzymes and how they act as catalysts to speed up chemical reactions, and substrates are the reactants of an enzymatic reaction.

As we move forward in our course, we'll be able to get some practice applying these concepts and we'll also learn a lot more about enzymes. So, I'll see you all in our next video.

Functions of Enzymes

So now that we know that enzymes are catalysts and they speed up chemical reactions to make those reactions go faster, in this video, we're going to introduce some of the functions of enzymes. It turns out that enzymes actually have a wide variety of functions in living cells. We're not going to talk about all of the different functions that enzymes can have, but some of those functions include the following three functions that we're showing you down below. The first is going to be building proteins. Enzymes are involved with building proteins and making sure that proteins are built at a fast rate.

You can see here that the enzyme is this little choo choo looking train here, and this choo choo looking train here is an enzyme that's called a ribosome, which is specifically going to be used to build proteins using messenger RNA. We'll be able to talk about this process of building proteins later in our course. But for now, what you can see here is that enzymes are involved with building proteins. This here represents the enzyme and it's building this protein that you see here. Enzymes are also really important for copying DNA. You can see in this image that the DNA is being copied or duplicated so that there are two copies of the DNA.

This is something that enzymes are involved with and help to make sure that this process occurs at a fast enough rate. Last but not least, enzymes are also involved with the digestion of food. When we eat our foods, enzymes are involved with breaking down the foods that are in our stomachs. You can see over here, this represents a picture of our stomachs, and the food that is in our stomachs is going to be broken down using enzymes, and enzymes speed up the reactions that break down the foods we digest. This here concludes our brief introduction to some of the functions that enzymes have, but the idea is that they are going to speed up chemical reactions and are involved with a wide variety of functions in living cells.

I'll be able to see you guys in our next video.

Which of the following are examples of the functions of enzymes?

• A. A lactase enzyme breaking down lactose sugar in the small intestine.
• B. A DNA polymerase enzyme synthesizing new strands of DNA.
• C. A lipase enzyme breaking down fats (lipids) in the small intestine.
• D. A helicase enzyme unraveling DNA so it can be replicated.
• E. All of the above.

Environmental Factors Affecting Enzyme Activity

In this video, we're going to talk about some environmental factors that affect enzyme activity. Enzyme activity is defined as a measure of the amount of product that is produced by an enzyme in a certain amount of time. If an enzyme produces a lot of product within a given amount of time, the enzyme has a lot of activity. But, if the enzyme only produces a little bit of product within a given amount of time, then the enzyme only has a little bit of activity. Many environmental factors can affect an enzyme's activity.

We're not going to talk about all the factors that can affect an enzyme's activity, but we will discuss three of those factors. These include the temperature, as the first environmental factor. The temperature can either include high temperatures, low temperatures, or temperatures in between the two. Another thing that could potentially affect the enzyme's activity is going to be the pH of the solution, whether the pH is acidic, neutral, or basic. Last but not least, the third environmental factor that we're going to talk about that affects enzyme activity is the concentration of reactants.

Depending on the concentration of reactants, the enzyme will have either high or low activity. It's also important to recall from our previous lesson videos that several environmental factors like high temperatures or even acidity can cause a protein to denature. Most enzymes are proteins, and thus, several environmental factors can cause enzymes to denature as well. Recall that denatured proteins or enzymes will lose their shape. When they lose their shape, they lose their function.

Denatured enzymes, because they lose their shape, therefore have decreased enzymatic activity. Basically, the temperature needs to be just right for an enzyme to have optimal activity. If the temperature is too high or even too low, the enzyme will not have optimal activity. The same goes for the pH. The pH cannot be too low or too acidic, or too high or too basic. Otherwise, that will affect the enzyme's activity and there needs to be a very specific pH for the enzyme to work optimally or at its best. The same goes for the concentration of reactants. If the concentration of reactants is too low, then the enzyme will not be able to produce a lot of product. If the concentration of reactants is too high, that could potentially oversaturate the enzyme, leading to the enzyme not working properly. This concludes our introduction to how environmental factors can affect enzyme activity, and we'll be able to get some practice applying these concepts as we move forward in our course.

So, I'll see you all in our next video.

Enzymes Example 1

So here we have an example problem that wants us to complete this sentence using one of these four potential answer options below. And it says, certain species of bacteria are able to perform metabolic reactions involving enzymes in hot springs where the temperatures are really hot because of which one of these reasons. Now the reason that bacteria are able to perform metabolic reactions in hot springs is that the enzymes that are involved actually have optimal temperatures that are really, really high. So their enzymes have high optimal temperatures. And so, these enzymes are going to work best in temperatures that are really high.

And so the correct answer here to this example problem is going to be option c. Now looking at some of the other options such as option b, it says, high temperatures make catalysis unnecessary, but really this is not true. Even in high temperatures, bacteria and other forms of life are going to require enzymes to catalyze their reactions. And so just because the temperatures are high does not mean that catalysis is going to be unnecessary. So this is simply not true.

And option d, it states that their enzymes are completely insensitive to temperatures, but this is also not going to be true. Enzymes are always going to be sensitive to their environments. And so, these enzymes that have high optimal temperatures, if we were to remove these bacteria from the hot springs and put them into a glacially cold environment, then those enzymes would not work the same. So it's not that their enzymes are insensitive to temperature.

It's just that their enzymes have high optimal temperatures. So option d here is not going to be correct. And then option a says that they are able to maintain a lower internal temperature, but bacteria that are in hot springs are really going to have the same temperature as their outside environment. And so this is really not going to be the reason for why these enzymes are capable of working properly in hot springs. And so once again, the correct answer to this problem here is because their enzymes have high optimal temperatures.

And so that concludes this example, and I'll see you all in our next video.

Which characteristics are likely associated with an enzyme isolated from a human stomach where conditions are strongly acidic.

• A. An enzyme that functions properly at 70 degrees Fahrenheit and at a neutral pH.
• B. An enzyme that functions properly at 98 degrees Fahrenheit and at an acidic pH.
• C. An enzyme that functions properly at 98 degrees Fahrenheit and at a neutral pH.
• D. An enzyme that functions properly at 70 degrees Fahrenheit and at an acidic pH.

Here’s what students ask on this topic:

What are enzymes and how do they function as catalysts?

Enzymes are biological molecules, typically proteins, that act as catalysts to speed up chemical reactions without being consumed in the process. They function by lowering the activation energy required for a reaction to occur, allowing the reaction to proceed more quickly. Enzymes bind to specific reactants, known as substrates, and convert them into products through a series of steps. This process is highly efficient and specific, meaning each enzyme typically catalyzes only one type of reaction. By facilitating these reactions, enzymes play crucial roles in various biological processes, including metabolism, DNA replication, and protein synthesis.

What are the main functions of enzymes in living cells?

Enzymes have several critical functions in living cells. Firstly, they are involved in protein synthesis, where they help build proteins by facilitating the translation of messenger RNA. Secondly, enzymes play a key role in DNA replication, ensuring that genetic information is accurately copied and passed on during cell division. Lastly, enzymes are essential for the digestion of food, breaking down complex molecules into simpler ones that can be absorbed and utilized by the body. These functions highlight the importance of enzymes in maintaining cellular processes and overall homeostasis.

How do temperature and pH affect enzyme activity?

Temperature and pH are critical factors that influence enzyme activity. Each enzyme has an optimal temperature and pH at which it functions most efficiently. Deviations from these optimal conditions can lead to decreased enzyme activity. High temperatures can cause enzymes to denature, losing their shape and functionality. Similarly, extreme pH levels, whether too acidic or too basic, can also denature enzymes. Therefore, maintaining the right temperature and pH is essential for optimal enzyme activity and overall metabolic efficiency.

What is enzyme denaturation and how does it affect enzyme activity?

Enzyme denaturation refers to the structural alteration of an enzyme, typically caused by extreme environmental conditions such as high temperature or extreme pH levels. When an enzyme denatures, it loses its specific three-dimensional shape, which is crucial for its catalytic function. As a result, the enzyme can no longer bind to its substrate effectively, leading to a significant decrease or complete loss of its catalytic activity. Denaturation is usually irreversible, meaning the enzyme cannot regain its original structure and function once denatured.

What are substrates in the context of enzymatic reactions?

In the context of enzymatic reactions, substrates are the specific reactants that an enzyme acts upon. When an enzyme catalyzes a reaction, it binds to its substrate(s) to form an enzyme-substrate complex. This binding facilitates the conversion of substrates into products through a series of chemical steps. The term 'substrate' is used specifically to indicate that an enzyme is involved in the reaction, distinguishing it from general reactants in non-enzymatic reactions. Understanding substrates is crucial for studying enzyme specificity and function.