Engage: Breaking It Down With Biostones
*Note* Do not try this at home.
These days, many companies use enzymes instead of stones to make stone-washed jeans. Read the article "Stone" Washing Jeans: Cellulases to see how working smarter, not harder makes a difference.
Explore: Rapid Reactions Investigation
You saw in the last section that enzymes are used to create a stone-washed effect in denim jeans using a fungal enzyme to break down dyes. This should give you an idea about one characteristic of enzymes, the ability to break something down. This observation might lead you to ask questions such as
Some of these questions are searchable online or in a library, and some you can answer by designing a laboratory investigation.
- Do all enzymes break things down?
- Can an enzyme break down more than one substance?
- After a substance breaks down, does the enzyme break down, too?
- Do enzymes work only at certain temperatures?
- How does the concentration of an enzyme affect a reaction?
In the investigation video below, students focus on the last question in the list, "How does the concentration of an enzyme affect a reaction?" If you think about it, manufacturers of stone-washed jeans probably asked the same question but in a different way such as, "How can we make stone-washed jeans lighter or darker?"
Pay close attention to the investigation to find out how concentration of an enzyme affects a reaction.
Many times lab investigations bring up more questions than answers. This leads a curious person into further research. He might design additional investigations, search the web, visit a library, or talk to an expert.
Additional questions might be
- How do enzymes work?
- Do all organisms have enzymes?
- What type of chemical are they?
- Is there ever a time that enzymes don't work?
In this animated activity, you will answer the question "Is there ever a time that enzymes don't work?" This time, the independent variable in the investigation is change in temperature. Let's ask the question another way: "How well does an enzyme reaction work if the temperature is increased?" To find out, click the letters displayed across bottom and count the number of reactions that take place.
Explain: Enzymes Increase Efficiency
Cells are possibly the smallest chemical factories in the world, and yet they are exquisitely efficient and productive. They build chemical compounds (anabolism) from imported raw materials and also break down larger molecules (catabolism) to access the necessary elements and energy to help maintain proper function. Cellular chemical processes are referred to as metabolism.
Metabolic reactions require a great amount of energy to take place (activation energy or EA). One way cells manage metabolic reactions is through the presence of enzymes. Enzymes are a type of protein that helps control and manage cell metabolism by making chemical reactions happen more efficiently than if the cell functioned without them. Enzymes lower activation energy normally required for chemical reactions to take place.
Enzyme compounds are three-dimensional molecules that have special bonding areas called active sites. At the active site of some enzymes, large molecules are broken into smaller molecules (catabolism). Other enzymes bond small molecules together to make larger compounds (anabolism). The molecules an enzyme metabolizes are known as substrates.
The shape of an enzyme’s active site is matched to the shape of the molecule it metabolizes. The substrate bonds to the active site, and the enzyme molecule firms up the attachment. If possible, take a moment to shake hands with someone. The way hands fit together and firm up in a hand shake is similar to how an enzyme-substrate complex bonds. This is called an “induced fit.”
Enzymes function best in specific conditions. However, environmental factors within the cell can affect how well an enzyme functions. High temperatures can denature (break down) an enzyme, changing its shape. Most enzymes work best in environments where pH range is 6 – 8. Higher or lower values in cells negatively affect enzyme function and, thus, cell function. An exception is digestive enzymes in the human stomach which work best in pH 2. Some enzymes work only in the presence of two other types of compounds, cofactors (such as zinc or iron) and coenzymes (such as vitamins). Other compounds inhibit enzyme function by either blocking the active site (competitive inhibitor) or bonding to the enzyme and changing its shape (noncompetitive inhibitor).
Enzymes are often referred to as catalysts because they increase efficiency in chemical reactions without being affected. Because of enzymes, cells can manage millions of chemical reactions per second without breaking a sweat. Because of enzymes, cells can harvest energy and raw materials from the food you eat and build a better you.
Elaborate: Enzymes in the Real World
Missouri Business enewsletter to read about how one couple's "greentech" startup company is becoming a big success by producing enzymes to help break down toxic wastes. Enzymes are big business in a variety of applications besides jeans, thanks to scientists who work in the field of molecular biology. Click
Now that you have read the article, do you have new questions? How does a company control enzyme production? How do the owners know which enzyme does what? How do the owners make enough enzymes to create a business and keep it going?
Let's go back to the scientists that started studying enzymes and the organisms that produce them. But before you proceed, there are a few things you will need to review
- Enzymes are a type of protein.
- Cells make proteins.
- DNA in cells has genetic codes for protein production.
- Genes code for enzymes.
Now you are ready to consider a specialized group of enzymes called restriction enzymes. Restriction enzymes are used to study gene expression of DNA sequences from the genomes of many organisms, including humans. It is because of the discovery of restriction enzymes that enzymes in general have become big business.
|This image is in the public domain courtesy of NASA.
Watch the three videos from Nature.com to get a better understanding of what restriction enzymes are and how they work.
Check out the "Related Items" section at the bottom of the page for additional articles about how other types of enzymes are used in the real world.