Facts of the Matter
Facts of the Matter
Sugar is essential to life
and yummy to eat, tooEveryone likes sugar! Because it's sweet. But sugar is much more than that. Sugar is truly the essence of life, and not just to those of us with a sweet tooth. Indeed, there are many kinds of sugar besides sucrose, which is the cane sugar that sweetens our coffee, pastries and other goodies.
All sugars belong to a category of nutrients we know as carbohydrates, meaning that the sugar molecules are made of carbon, hydrogen and oxygen atoms. There are many different ways to arrange these three atoms. Certain arrangements form the compounds that chemists call sugar.
Although all sugar molecules are similar in shape, the number of atoms and the way they are arranged differ from one sugar to another.
Simple sugars are rings of carbon atoms with hydrogen and oxygen atoms sticking out like toothpicks in a doughnut. Complex sugars such as sucrose are built from simple sugars by connecting them into various configurations.
Glucose, also known as dextrose, is a simple sugar. It is the most abundant organic chemical on the planet and perhaps the most important as well. It is the primary sugar produced by photosynthesis and the ultimate source of energy in cells. The glucose molecule stores energy from the sun in a form that can be transported to plant and animal cells. Their cells release the energy through metabolism and use the energy to power the cells and to build proteins and other essential biochemicals. In insects and animals, digestive enzymes break down complex sugars into simple sugars; ultimately all sugars are converted to glucose, which is carried to cells in animals and plants.
Like glucose, the names of common sugars all end in -ose, as in fructose, sucrose, maltose and lactose. Sucrose is the complex sugar that cane and beets produce by linking molecules of glucose and fructose. Fructose is a simple sugar that is modified from glucose as fruits ripen. In addition to fructose, each type of fruit produces additional sugars that give that fruit its unique taste.
Maltose is complex sugar formed when the starchy pulp of grains such as wheat, barley and rice breaks down as the seed sprouts. It is the 'malt' from which beer is brewed.
Lactose is milk sugar. It is a complex sugar that must be broken down to simple sugars by a digestive enzyme that most children have but which is not in the digestive repertoire of lactose-sensitive adults.
When many molecules of glucose are joined end to end, they form the complex carbohydrates we call starch. Still longer chains of linked glucose form the various plant fibers that support good health. Longer yet, and there is the cellulose in the wood fibers of our furniture and buildings.
As important as they are in providing energy, sugars are much more than just vehicles for its storage and transportation. Ribose and deoxyribose, both simple sugars, are part of the genetic information of a cell. They are important components of the DNA and RNA molecules that hold the blueprint and assembly instructions for building, growing and maintaining entire organisms.
It is clear that sugars are essential to life. Along with amino acids, they are all that is needed to build and maintain life, whether it be a single-cell or complex multicellular beings such as ourselves. Both amino acids and complex sugars have been observed in deep space, in comets and on meteorites, opening the distinct possibility that the earth was bombarded with the materials of life early in its history. It's just possible that genesis came from the heavens after all!
We could all be a little smarter, no? Richard Brill picks up
where your high school science teacher left off. He is a professor of science
at Honolulu Community College, where he teaches earth and physical
science and investigates life and the universe.
He can be contacted by e-mail at rickb@hcc.hawaii.edu