Sucrose is the chemical name for table sugar, a calorie-providing carbohydrate that occurs naturally in fruit and is a common food additive. Like all carbohydrates, sucrose provides 4 calories per gram consumed. If you eat more sucrose than your cells need, they can store the excess in the form of fat.
Sucrose
The sucrose molecule is a disaccharide, meaning it's a carbohydrate made up of two smaller sugar units. The specific smaller units making up sucrose are glucose, which is ubiquitous in nature, and fructose, or fruit sugar. Its chemical formula is C12H22O11, which is identical to that of other common dietary sugars, including lactose, or milk sugar. Sucrose is much sweeter than lactose and many other sugars because it binds tightly to the sweetness receptor in the mouth.
Digestion and Absorption
Your small intestine can't absorb sucrose directly. Instead, when you eat it, you have to break it into its glucose and fructose components -- which your small intestine can absorb -- using the enzyme sucrase. Once you've absorbed glucose and fructose into the bloodstream, your cells take the smaller sugar units up according to their need. They can then burn these smaller sugars for energy or convert them into other chemical forms.
Burning Sugars
Both glucose and fructose react with various enzymes in cells to produce energy -- a total of 4 calories per gram. A calorie is a measure of heat or energy; food calories contain enough energy to heat a liter of water by 1 degree Celsius. You can use the calories of energy liberated from sucrose to produce body heat or provide for cellular energy needs; cells use energy to make molecular products, communicate and produce movement.
Other Uses
You can store the calories in sucrose for later use if you don't need them right away. One storage form is called glycogen; this is a carbohydrate made by the liver and muscles, and provides for cellular needs during times of fasting. Alternately, you can convert glucose and fructose from sucrose into triglycerides, which are fat molecules that you store in adipose tissue. You can then break down fat if you're calorie-deficient later on.
References
- "Human Physiology"; Lauralee Sherwood, Ph.D.; 2004
- "Biochemistry"; Reginald Garrett, Ph.D. and Charles Grisham, Ph.D.; 2007
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