Enzymes - Online Tutor, Practice Problems & Exam Prep

Enzymes are biological catalysts that accelerate chemical reactions without being consumed. They convert substrates (reactants in enzymatic reactions) into products efficiently. Key functions include protein synthesis, DNA replication, and food digestion. Enzyme activity is influenced by environmental factors such as temperature, pH, and reactant concentration. Optimal conditions are crucial; deviations can lead to denaturation, reducing enzymatic function. Understanding these concepts is essential for grasping biochemical processes 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 it's 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.

Now 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, what we're showing you are 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 absolutely 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, and the same reaction over here we have, the substance being converted into the products. And this time, notice that an enzyme is present and the enzyme is represented by this structure that you see down below. And so, the enzyme's job, its function is to catalyze or speed up the chemical reaction so that it occurs much, much faster.

As a result, the same reaction is able to occur at a much, much faster rate thanks to the enzyme, and so enzymes are all about catalyzing or speeding up chemical reactions.

Now what's also important to note is that the term substrates is referring to the reactants of a chemical reaction that is catalyzed by an enzyme. And so, 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 exact thing as the reactants, and really the only difference is that substrates implies that an enzyme is involved, whereas reactants do 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.

We'll be able to get some practice applying these concepts as we move forward in our course, and we'll also get to learn a lot more about enzymes as we move forward. 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. And 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, and 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. And you can see this here represents the enzyme, and it's building this protein that you see here.

Now enzymes are also really important for copying DNA. Here, 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.

And then 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. Enzymes speed up the reactions that break down the foods that we digest.

This 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.

• 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, then 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 actually affect an enzyme's activity, and we're not going to talk about all of the factors that can affect an enzyme's activity, but three of those factors we are going to discuss below. These include the temperature, as the first environmental factor. Temperature can include high temperatures, low temperatures, or just temperatures in between the two.

Another factor that could potentially affect the enzyme's activity is the pH of the solution, whether the pH is acidic, neutral, or if the pH is basic. Lastly, the third environmental factor that we're going to discuss 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. Enzymes are mostly proteins, and several environmental factors can cause enzymes to denature as well. Denatured proteins or enzymes lose their shape and, when they lose their shape, they lose their function. Denatured enzymes, because they lose their shape, will consequently have decreased enzymatic activity.

The temperature needs to be just right in order for an enzyme to have optimal activity. If the temperature is too high or too low, then the enzyme will not have optimal activity. The same goes for the pH; it cannot be too low or too acidic, or too high or too basic. Otherwise, that will affect the enzyme's activity. There needs to be a very specific pH in order 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 products. If the concentration is too high, then that could potentially oversaturate the enzyme and also lead 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 here using one of these four potential answer options down below. 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 because the enzymes that are involved are actually going to 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 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, because the temperatures are high does not mean that catalysis is going to be unnecessary. So this is simply not true. And option d says 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 them, it 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.

• 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 in living organisms. 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, at their active site, forming an enzyme-substrate complex. This interaction facilitates the conversion of substrates into products. Importantly, enzymes are not consumed or permanently altered during the reaction, meaning they can be used repeatedly. This catalytic property is crucial for maintaining the efficiency of metabolic processes in cells.

What are the main functions of enzymes in living cells?

Enzymes perform a wide variety of functions in living cells. Three key functions include: 1) Protein synthesis: Enzymes like ribosomes facilitate the assembly of amino acids into proteins using messenger RNA as a template. 2) DNA replication: Enzymes such as DNA polymerase help in copying DNA, ensuring genetic information is accurately passed on during cell division. 3) Food digestion: Digestive enzymes break down complex food molecules into simpler forms that can be absorbed and utilized by the body. These functions are essential for growth, repair, and energy production in living organisms.

How do temperature and pH affect enzyme activity?

Temperature and pH significantly influence enzyme activity. Each enzyme has an optimal temperature and pH at which it functions most efficiently. Deviations from these optimal conditions can reduce enzyme activity. High temperatures can cause enzymes to denature, losing their shape and function. Similarly, extreme pH levels (too acidic or too basic) can alter the enzyme's structure, affecting its ability to bind substrates. Therefore, maintaining optimal temperature and pH is crucial for ensuring maximal enzymatic activity and efficient metabolic processes.

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, particularly at the active site. This loss of shape results in the enzyme's inability to bind to its substrate effectively, leading to a significant decrease or complete loss of its catalytic activity. Denatured enzymes cannot facilitate chemical reactions efficiently, disrupting metabolic processes in cells.

What are substrates in the context of enzymatic reactions?

In enzymatic reactions, substrates are the specific reactants that enzymes act upon. When a substrate binds to an enzyme's active site, an enzyme-substrate complex is formed. This interaction facilitates the conversion of the substrate into the product(s) of the reaction. The term 'substrate' is used specifically to denote the reactants in reactions catalyzed by enzymes, distinguishing them from general reactants in non-enzymatic reactions. Understanding substrates is crucial for studying how enzymes function and regulate biochemical pathways.