Science & Technology in Action

1st Edition

Improving Human Life


This lesson deals with the phenomenon of the living organism. It distinguishes unicellular and multicellular organisms and defines the concept of the biological catalyst. It also covers the effects of vitamins on enzymes.
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Lesson excerpt

What is life?
This lesson looks at the role of enzymes in life processes. We see what enzymes do and why it is important. We examine their characteristics and we look at why vitamins can be important for enzyme function. Scientists who work in pharmaceutical companies such as Wyeth know all about the function and role of enzymes in the human system. This knowledge enables them to produce substances such as vitamins which help us to maintain healthy bodies.

It is very difficult to define life. The classic characteristics that distinguish living from non-living matter are organisation,nutrition, excretion, response, and reproduction.

Other characteristics could be added to this list, like self-generatedgrowth and movement, capable of evolution and use ofnucleic acid (DNA, RNA) for information storage and hereditary material.

When it comes to organisation, all living organisms are composed of one or more cells. Bacteria, yeast and Amoeba are unicellular. Human beings are multicellular. Our bodies contain about 1014cells. 

What is a cell?
The cell is the functional unit of life. Its physical and chemical organisation is extremely complex. Scientists have been studying cells intensely since the first cell was identified almost 350 years ago, but it’s thought that today we understand only about 1% of cell metabolism.

What is metabolism?
Metabolism is the complete set of chemical reactions occurring within an organism in the process of living and reproducing.

Metabolism is very complex. At any instant at least 4,000 different chemical reactions are running in perfect coordination in the average human cell, and over 12,000 in a brain cell. To put this in context, remember a human cell is about 0.01 mm in diameter – about 30 would fit in single file across the full stop at the end of this sentence. 

True or False?

  1. DNA and RNA are two different types of proteins. false
  2. All bacteria are unicellular. true
  3. An enzyme is an inorganic catalyst. false
  4. After every reaction a new enzyme has to be made. false
  5. Enzymes speed up metabolism. true
  6. Enzymes cause many new reactions to take place. false
  7. The capture location in an enzyme is known as the 'reaction site'. false
  8. An enzyme can catalyse a variety of reactions. false
  9. Enzyme action is irreversible. false
  10. pH does not have any influence on enzyme action. false
  11. Enzymes allow reactions to occur at a lower temperature than normal. true
  12. Vitamin deficiency can result in reduced enzyme activity. true