|
Enzymes are fascinating biological molecules that play a crucial role in speeding up chemical reactions in living organisms. They act as catalysts, which means they help speed up reactions without being consumed or permanently altered themselves. Enzymes make it possible for the chemical processes in our bodies to happen at a speed that is essential for life.
To understand how enzymes work, let's use a simple analogy: Imagine you have a lock (the chemical reaction) that requires a specific key (the reactants) to open it and produce a valuable item (the product). However, the key is too big, and you can't insert it into the lock easily. This is where the enzyme (a specialized key cutter) comes into play. 1. Substrate and Active Site: The reactants in a chemical reaction are called substrates, and the region of the enzyme where the substrates bind and the reaction takes place is known as the active site. The active site is a specifically shaped pocket on the surface of the enzyme that accommodates the substrates, like a lock and key fit. 2. Enzyme-Substrate Complex: When the substrates come into contact with the enzyme, they fit into the active site like a key fitting into a lock. This interaction creates an enzyme-substrate complex. 3. Reaction and Product Formation: During the reaction, the substrates are transformed into products. The enzyme plays an active role in this process by facilitating the breaking and forming of chemical bonds between the substrates. After the reaction, the enzyme releases the products and is now free to aid in the next reaction. 4. Enzyme Recycling: The enzyme is not consumed during the reaction, so it can be used repeatedly. This efficiency is one of the reasons why enzymes are essential in living organisms. They enable biochemical reactions to occur at a rate that is necessary for maintaining life processes. Enzymes are highly specific, meaning each type of enzyme is designed to catalyze a specific reaction or a group of related reactions. This specificity is due to the precise shape of the enzyme's active site, which allows only certain substrates to fit into it. In summary, enzymes work by providing an optimal environment for chemical reactions to occur, lowering the activation energy required for the reaction to proceed. They do so by binding to the substrates and forming an enzyme-substrate complex, which facilitates the reaction and leads to the formation of products. Enzymes are essential for the proper functioning of living organisms and are involved in a wide range of biochemical processes in our bodies. |
Enzymes are proteins and as such they only work because they have a very specific shape.
|
During cellular respiration, multiple reactions occur that ultimately take glucose and oxygen molecules and rearrange them into water and carbon dioxide.
REMEMBER - Cellular Respiration -
REMEMBER - Cellular Respiration -
But sometimes these reactions do not occur perfectly. Instead of forming water, sometimes hydrogen peroxide (H2O2) is formed instead. Hydrogen peroxide is dangerous to cells. Too much hydrogen peroxide results in cell death.
Hydrogen peroxide naturally breaks down into water and oxygen gas. This is good because water and oxygen are not dangerous to our cells. But this natural process takes way too long. If it builds up, the hydrogen peroxide would kill our cells long before it naturally breaks down into water and oxygen. But our cells have evolved a way to speed up this natural reaction.
Catalase is an enzyme (protein) that speeds up the breakdown of hydrogen peroxide into water and oxygen. Enzymes are protein "tools" and like tools, they assist in the reaction but are not used up in the reaction. A single hammer can hammer in many nails. In the same way, catalase isn't used up in the reaction. It can speed up the breakdown of many molecules of hydrogen peroxide. The specific reaction we will be looking at is:
2H2O2 → 2H2O + O2 (gas)
Hydrogen peroxide naturally breaks down into water and oxygen gas. This is good because water and oxygen are not dangerous to our cells. But this natural process takes way too long. If it builds up, the hydrogen peroxide would kill our cells long before it naturally breaks down into water and oxygen. But our cells have evolved a way to speed up this natural reaction.
Catalase is an enzyme (protein) that speeds up the breakdown of hydrogen peroxide into water and oxygen. Enzymes are protein "tools" and like tools, they assist in the reaction but are not used up in the reaction. A single hammer can hammer in many nails. In the same way, catalase isn't used up in the reaction. It can speed up the breakdown of many molecules of hydrogen peroxide. The specific reaction we will be looking at is:
2H2O2 → 2H2O + O2 (gas)
Yeast are microorganisms made of single cells. Yeast perform cellular respiration, which means they accidentally make hydrogen peroxide. In order to get rid of the dangerous hydrogen peroxide, yeast also makes catalase enzymes.
For this lab, you will be measuring the rate of the reaction using yeast as the source of catalase and 3% hydrogen peroxide solution. The yeast are trapped in spheres that sink in hydrogen peroxide. The catalase, made by the yeast, breaks down the hydrogen peroxide into water and oxygen gas. The oxygen gas causes the yeast to float. The faster the oxygen gas is made the faster the yeast will float. You will be timing how long it takes for the yeast to reach the surface of the hydrogen peroxide.
For this lab, you will be measuring the rate of the reaction using yeast as the source of catalase and 3% hydrogen peroxide solution. The yeast are trapped in spheres that sink in hydrogen peroxide. The catalase, made by the yeast, breaks down the hydrogen peroxide into water and oxygen gas. The oxygen gas causes the yeast to float. The faster the oxygen gas is made the faster the yeast will float. You will be timing how long it takes for the yeast to reach the surface of the hydrogen peroxide.
Materials:
For each temperature, you will do the following:
Make sure you are on the correct tab for your class period and that you put the data into the column with your name at the top. This will allow us to make sure everyone is collecting suitable data.
If you are virtual, you will use the recordings of the lab below. There are two videos, each with 5 trials. You will need to watch each video five times in order to record the time for each yeast sphere independently. (HINT: It will be easier to time the yeast spheres if you make the video full-screen on your device.)
- Yeast/alginate spheres
- 50 ml graduated cylinder
- 1% hydrogen peroxide
- Forceps (tweezers)
- Timer/stopwatch - you can use your phone
- 1 paper towel
- Ruler
For each temperature, you will do the following:
- Pour approximately 50ml of 1% hydrogen peroxide into a 50ml graduated cylinder.
- Measure the height of the liquid in the graduated cylinder. Record the height, in centimeters, in the data table.
- Using forceps, gently remove one yeast sphere from the petri dish. Leave the rest of the yeast in the petri dish so they stay hydrated.
- Drop the sphere into the graduated cylinder. As soon as the sphere touches the bottom of the graduated cylinder, start the timer. Stop the timer when the sphere reaches the surface of the hydrogen peroxide. Record the time (in seconds) in your data table. Only put numbers into the data table - ie. if it takes 12 seconds to reach the surface put the number "12" into the data table, not "12 seconds".
- Use forceps to remove the yeast sphere from the graduated cylinder and place it on a paper towel.
- Repeat the procedure for a total of 10 different yeast spheres.
- Dispose of the yeast spheres in the trash. (Do NOT pour them down the drain!)
- Pour the hydrogen peroxide into the class waste container (Do NOT pour it down the drain!)
Make sure you are on the correct tab for your class period and that you put the data into the column with your name at the top. This will allow us to make sure everyone is collecting suitable data.
If you are virtual, you will use the recordings of the lab below. There are two videos, each with 5 trials. You will need to watch each video five times in order to record the time for each yeast sphere independently. (HINT: It will be easier to time the yeast spheres if you make the video full-screen on your device.)
|
|
|