Enzymes Flashcards
What is an Enzyme?
An enzyme is a biological catalyst because it speeds up the rate of reaction but remains unchanged at the end of reaction.st
state some important functions of enzymes.
They are globular proteins and fold up into precise shapes.
Almost all metabolic reactions that take place in living organisms are catalysed by enzymes.
Mostly the names of the enzymes end with ase- Amylase andATPase.
what are intracellular and extracellular enzymes?
give examples
Those enzymes which work inside cell is called intracellular. Enzymes that are excreted by cells and catalyse reactions outside cell are known as extracellular enzymes. Digestive enzymes in our gut are example of extracellular enzymes.
State the lock and key hypothesis.
Enzymes have specific feature called active site. The active site of an enzyme is a region to which another molecule or molecules can bind. This molecule is substrate of enzyme.
The shape of the active site allows substrate to fit perfectly. The idea enzyme has particular shape into which substrate fits exactly is known as lock and key hypothesis.
deduce what is meant by the enzyme substrate complex
The substrate is key whose shape fits the lock of enzyme. The substrate is held in place by temporary bonds which form between the substrate and some of the R groups the enzymes amino acids. This entire structure is termed enzyme substrate complex.
How does the enzyme show specificity?
Each enzyme will act only on one type of substrate molecule. This is because the shape of the active site will allow one shape of molecule to fit. The enzyme is said to be specific for that substrate. This is how enzyme shows specificity.
deduce what is meant by induced fit model?
Lock and key hypothesis was modified in the light of evidence that enzyme molecules are more flexible than suggested in rigid lock and key.
It is usually the same as lock and key hypothesis, but adds the idea that the enzyme and sometimes the substrate, can change shape slightly as the substrate molecule enters the enzyme, in order to ensure a perfect fit. This makes catalysis more efficient. This modern hypothesis for enzyme action is induced fir hypothesis.
What type of reactions may an enzyme molecule catalyse?
An enzyme may catalyse reaction in which substrate molecule is split into two or more molecules or alternatively it may catalyse the joining together of two molcules, as making dipeptide from two amino acids.
The enzyme substrate complex formed before the release of product. When the reaction is complete the product or products leave active site. The enzyme is unchanged in this process, so it is avaiable to receive another substrate molecule.
How an enzyme catalyses the breakdown of substrate molecule into two product molecules?
1) An enzyme has a cleft in its surface, called active site. The substrate molecule has complementary shape.
2) Random movement of enzyme and substrate brings the substrate into the active site. An enzyme substrate complex is temporarily formed. The R groups of amino acids in the active site interact with substrate.
3) The interaction of the Substrate with the active site breaks the substrate apart. An enzyme product complex is formed before the two product molecules leave the active site, leaving the enzyme molecule unchanged and ready to bind with another substrate molecule.
What is meant by activation energy?
In many chemical reactions, the substrate is not converted to a product unless some energy is added. This energy is called activation energy.
Enzymes avoid this problem because they decrease the activation energy of reactions they catalyse..They do this by holding substrate molecules together so that they can react together easily. As a result, reactions catalysed by enzymes take place at much lower temperatures.
