The instigators ...
Adrian Whyte and Joanna Johnson, Contributor

Students participating in a cheerleading competition.

BIOLOGY IS the study of living things. We also study the interaction of living things with their environment. For this level of biology we tend to focus on the characteristics of living things.

During your study of CXC biology, it is not only important that you know what process is going on, but you should also be able to describe the steps of the process, explain its importance and state where it is happening.

Apart from studying the characteristics of living things, there are some fundamental topics that need to be understood in all clarity since they are the threads which hold the various areas of biology together. For this reason we will be starting our studies on one of these foundation topics: A study of enzymes.

One fundamental thing about ALL organisms is that they all contain enzymes, and furthermore they all need enzymes for their survival.

Reactions that take place within any organism (metabolic), that sustain its life, take place in the presence of enzymes. Without the presence of enzymes, metabolic reactions would be extremely slow that life would not exist.

Consider the following:

Fighting was never a common problem at Blank high for many years. Yes, there were a lot of arguments but rarely a punch thrown. This all stopped since the new year when some new students joined the school. Interestingly enough, the new students were never caught fighting; however, whenever or wherever a punch is thrown both Amy Lace and Eu Race were always present.

Though Amy and Eu never actually took part in the fight; it was found that they were the ones who would prompt arguing students into a fight.

Question: What substance in all organisms behaves like Amy Lace and Eu Race?
Answer: Enzymes

EXPLANATION:

Though Amy and Eu never took part in a fight, they were always the ones responsible getting a fight started. Well this is how enzymes work; they never take part in a reaction but they are responsible for getting the reaction to occur.

From our story Amy and Eu represent the enzymes, in that they cause a reaction (the fight) to occur, without taking part in the reaction.

WHAT ARE ENZYMES?

* Enzymes are biological molecules that cause a reaction to occur, but remain unchanged at the end of the reaction.

* Virtually every reaction that occurs within a living organism is brought about by an enzyme

PROPERTIES OF ENZYMES:

* they are proteins ­ made in all cells from amino acids
* they have an active site ­ this is where a reaction takes place
* they are specific ­ each enzyme can only control one type of reaction
* they are reusable ­ because they are not changed or damaged by a reaction
* they work best at a particular temperature (optimum temperature)
* they work best at a particular pH (optimum pH)
* they are denatured (destroyed) at high temperatures

Q1 Identify two processes in plants and animals that require the use of an enzyme.

HOW DOES TEMPERATURE AFFECT AN ENZYME?

AT LOW TEMPERATURES

* there is a lower rate of reaction as there is less heat (kinetic) energy, therefore, both the enzyme and substrate will move slowly

* increasing the temperature provides more energy (kinetic energy) therefore, both enzyme and substrate will move faster

* the faster movement of the enzyme and
substrate increase the chance of them colliding into each other; the more collision the faster the rate of reaction until optimum temperature is reached.

AT HIGH TEMPERATURES

* the heat energy makes the bonds holding the protein structure (enzyme) vibrate

* the vibration breaks the bonds, which changes the shape of the protein (enzyme)

* the change in shape of the enzyme denatures (destroys) it

* these changes in the enzyme and the active site cause the substrate to no longer fit

* it the substrate no longer fits the enzyme is unable to function, no reaction.

Q2 State TWO factors that affect the way enzymes work.

Q3 Explain the effect of the factors you identified.

Q4 How would you account for the changes you would observe in a Temperature vs. Rate of reaction graph?

KEY TERMS TO KNOW:

* Substrate
* Denature
* Active site
* Optimum temperature

* Adrian Whyte and Joanna Johnson teach Biology at Ardenne High School.