Mr. T's Science Scene


So far we have been talking about sugar and its role in respiration (how the sugar is split in the cytoplasm and so forth and so on until ATP (energy) is made).  Now we will learn about sugar's distant cousins, starch, protein, and fat (lipids).  These are the four main nutrients that you get from food and which your bodies use to build you, make you work, make you grow, etc.  Other nutrients are vitamins and minerals- which help chemical reactions in your body and make up your bones- and water!

Proteins are widely distributed in nature and no living organisms are known without them.  Humans and animals use proteins for the growth and repair of tissues.  The protein-rich foods from animal sources contain complete proteins, which supply all the building blocks (amino acids) necessary in an animal’s diet.  Protein can also be found in a variety of nuts and nut products.  Proteins are used in a wide variety of chemicla and microscopic processes such as enzymes, transfer proteins, and holding DNA together.

As you eat protein (foods or food products from animals) your digestive system breaks down the animal protiens to their amino acids.  Those amino acids are distributed to your cells and "hang out" in your cytoplasm to be used by your ribosomes to make parts of you!  So you really ARE what you EAT!

Carbohydrates are the most abundant food sources of energy.  Important dietary carbohydrates are divided into two groups:

STARCHES (complex carbohydrates):  The starches, which come from plants and are broken down into sugars in plants or in other organisms, are supplied in the grains (bread, wheat, rice), the tubers (potatoes), and some rhizomes and roots.  Starch supplies long term energy.  The energy is long term because the starch molecule is a long chain of sugars!  So, the body "breaks off" a link (or sugar) from the starch molecule (chain) and THEN uses it in the mitochondria for energy.  In this way, the process of getting sugar for use in the mitochondria takes longer and lasts longer as an energy source.


SUGARS (simple carbohydrates): The sugars occur in many plants- especially fruits; the most important being sucrose (table sugar), which is obtained from sugarcane or sugar beet.  Sugars are generally sweet tasting, dissolve easily in water, and form white or clear crystals when purified.  PHOTOSYNTHESIS (using light to make sugar) serves to make sugars as a food source for plants.  Sugar supplies short term, immediate energy.  Sugar is short term energy because it is immediately used by the cell's mitochondria to make energy.  This is why "carbing up" involves the eating of pasta instead of candy!

Fats or Lipids are widely distributed in nature and are a concentrated food source of stored energy.  There are two kinds of fats, saturated and unsaturated.  Saturated fat can be found in animal products such as meat (animals) while unsaturated fats are most commonly found in plants.  Saturated fat is solid at room temperature and has a solid white appearance.  Unsaturated fat is a liquid at room temperature- like oils.  Examples of the two fats are:

Saturated ----> fat from french fries, animal fat, meat, butter, lard, et.


Unsaturated -----> oils; typically from plants



Home Unit