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Biological
molecules structure and functions
Joanna
George-Johnson, Contributor
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| Taking
notes is an important part of the academic process as these male students at Bridgeport
High School show. - Anthony Minott/Freelance Photographer | There
are some molecules that can be found in all organisms. Today we will look at a
few in detail. There
are two categories of these molecules: organic and inorganic. Organic
molecules: these molecules contain the element carbon, hydrogen and oxygen.
The molecule MUST have carbon and hydrogen. However, the organic molecules found
in most organisms also contain oxygen. Inorganic
molecules: these molecules do not contain carbon and hydrogen in their structure.
Note well, they may have carbon or hydrogen but never the two at the same time.
The
main molecules are: - Water
- Carbohydrates
- Proteins
- Lipids
(fats)
- Deoxyribonucleic
acid (DNA)
Water
This
molecule is one of the most important molecules in life. It makes up over 70 per
cent of the human body. It is involved in ALL metabolic reactions that occur in
both plants and animals. It is important for maintenance of the blood consistency.
It also
help with the maintenance of the body temperature and many other functions. (The
details of why it is such a special molecule in life involve more advanced study
and won't be focused on here.) Formula:
H2O 
Carbohydrates
Carbohydrates
are a large group of molecules that perform a few functions. Structure
of Carbohydrates: All
carbohydrates contain the elements carbon, hydrogen and oxygen. The simplest of
carbohydrates are called monosaccharides. The ability of monosaccharides to join
together leads to the formation of many types of carbohydrates. One of the most
known monosaccharides is glucose. When
glucose and fructose (a next type of monosaccharide) join together, a next well
known molecule is formed - sucrose. Sucrose is the sugar that most of us use to
sweeten our beverages and desserts, etc. Therefore,
small carbohydrates are sugars. The larger carbohydrates include starch - found
in plants - and is made from lots of glucose molecules joining together. Glycogen
is also a very important carbohydrate. It is found in animal cells. It is very
similar to starch, and like starch, is made by many glucose molecules joined together.
There
is also cellulose, also found in plants. It is a large carbohydrate. As carbohydrates
get larger, they are no longer sweet. Large
carbohydrates are made by the joining of many monosaccharides; the result molecule
is called a polysaccharide. 
Function
- The
main function of carbohydrates is to provide energy for the organism.
- In
the case of cellulose, the carbohydrate performs a structural function to plants.
This molecule accounts for the rigidity of plant cells.
Dietary
sources of carbohydrates include cakes, breads, yam, potato and any other starchy
foods. Adenosine
Triphosphate (ATP) ATP
is a molecule found in all cells. It is the energy currency of all living things!
Just as a car uses gasolene as an energy source, living things uses ATP to carry
out all activities and reactions. Therefore, from a bacterium to a human being
or a plant, we all use the same energy currency! Questions
1.
Give two other sources of carbohydrates. 2.
Determine what type of molecule is a) water b) carbohydrate. 3.
In what metabolic process is the energy from carbohydrates is released? Joanna
George-Johnson teaches at Ardenne High School.
Email: Masterbio@gmail.com.
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