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After the primary structure comes the secondary structure. The original chain begins to twist. It's as if you take a piece of string and twist one end. It slowly begins to curl up. In the amino acid chain, each of the amino acids interacts with the others and it twists like a corkscrew or a flat folded sheet.


Let's move on to the tertiary structure of proteins. By now you're probably getting the idea that proteins do a lot of folding and twisting. The third step in the creation of a protein is the tertiary structure when the amino acid chains begin to fold even more and bond using more bridges (the disulfide bridges).


We can finally cover the quaternary structure of proteins. Quaternary means four. This is the fourth phase in the creation of a protein. In the quaternary structure, several amino acid chains from the tertiary structure fold together in a blob. They wind in and out of each other. You heard it right. Blob is the scientific term.



In our class, we often talk about reactions and the molecules that change in those reactions. Those changes don't happen on their own. If you leave a blob of protein in a Petri dish, will it just break down to the amino acids? No. What will do it? Enzymes! Enzymes are the biological substance (proteins) that act as catalysts and help complex reactions occur everywhere in life.


When you go home at night and the door is locked, can it open itself? Nope. You need a key that is just the right shape to fit in that lock. Otherwise, you're stuck in the cold. (to fit= to be the right size and shape for (someone or something) ▪ The suit fits him perfectly. ▪ I hope this key fits the lock. ▪ The two pieces fit each other perfectly. ▪ These shoes fit perfectly. ▪ This calculator will fit nicely/neatly in your shirt pocket. ▪ pants that fit tightly/loosely = tight-fitting/loose-fitting pants ▪ The two pieces fit together perfectly. ◊Something that fits (you) like a glove fits (you) very well.
▪ That suit fits him like a glove). Enzymes work in a similar way (locks and keys). Enzymes complete very specific jobs and do nothing else. They are very

specific locks and the compounds they work with are the special keys. In the same way there are door keys, car keys, and bike-lock keys, there are enzymes for neural cells, intestinal cells, and your saliva.

Here's the deal: there are four steps in the process of an enzyme working.
1. An enzyme and a substrate are in the same area. The substrate is the biological molecule that the enzyme will attack.
2. The enzyme grabs onto the substrate with a special area called the active site. The active site is a specially shaped area of the enzyme that fits around the substrate. The active site is the keyhole of the lock.
3. A process called catalysis happens. Catalysis is when the substrate is changed. It could be broken down or combined with another molecule to make something new.
4. The enzyme lets go. Big idea. When the enzyme lets go, it returns to normal, ready to do another reaction. The substrate is no longer the same. The substrate is now called the product.


Good question! We know what you're thinking. What if enzymes just kept going and converted every molecule in the world? They would never stop... like a monster! There are many factors that can regulate enzyme activity, including temperature, activators, pH levels, and inhibitors.


Date: 2016-01-03; view: 592

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