carbohydrates

Examples of carbohydrates in the following topics:

• Carbohydrates: Sources, Uses in the Body, and Dietary Requirements

  • Carbohydrates, which break down to glucose, are a major source of energy for humans, but are not an essential nutrient.
  • Carbohydrates are a common source of energy in living organisms , however, a carbohydrate is not an essential nutrient in humans.
  • Carbohydrate and protein contain 4 kilocalories per gram, while fats contain 9 kilocalories per gram.
  • Organisms typically cannot metabolize all types of carbohydrate to yield energy.
  • Called "dietary fiber," these carbohydrates enhance digestion, among other benefits.

• Importance of Carbohydrates

  • Carbohydrates are, in fact, an essential part of our diet; grains, fruits, and vegetables are all natural sources of carbohydrates.
  • Carbohydrates have been a controversial topic within the diet world.
  • Calorie-wise, a gram of carbohydrate provides 4.3 Kcal.
  • Without the consumption of carbohydrates, the availability of "instant energy" would be reduced.
  • Eliminating carbohydrates from the diet is not the best way to lose weight.

• Metabolism of Carbohydrates

  • Organisms break down carbohydrates to produce energy for cellular processes, and photosynthetic plants product carbohydrates.
  • Carbohydrates are one of the major forms of energy for animals and plants.
  • Plants build carbohydrates using light energy from the sun (during the process of photosynthesis), while animals eat plants or other animals to obtain carbohydrates.
  • Plants store carbohydrates in long polysaccharides chains called starch, while animals store carbohydrates as the molecule glycogen.
  • Plants and some other types of organisms produce carbohydrates through the process called photosynthesis.

• Contour Plots

  • Consider the Figure 1 that contains data on the fat, non-sugar carbohydrates, and calories present in a variety of breakfast cereals.
  • Each line shows the carbohydrate and fat levels for cereals with the same number of calories.
  • Note that the number of calories is not determined exactly by the fat and non-sugar carbohydrates since cereals also differ in sugar and protein.
  • A contour plot showing calories as a function of fat and carbohydrates
  • A contour plot showing calories as a function of fat and carbohydrates with areas shaded.

• Glucose

  • Carbohydrates are the most abundant class of organic compounds found in living organisms.
  • Carbohydrates are called saccharides or, if they are relatively small, sugars.
  • Several classifications of carbohydrates have proven useful, and are outlined in the following table.
  • Carbohydrates have been given non-systematic names, although the suffix ose is generally used.
  • The most common carbohydrate is glucose (C6H12O6).

• Digestive Processes of the Small Intestine

  • The small intestine uses different enzymes and processes to digest proteins, lipids, and carbohydrates.
  • The three major classes of nutrients that undergo digestion are proteins, lipids (fats), and carbohydrates.
  • Pancreatic amylase breaks down some carbohydrates (notably starch) into oligosaccharides.
  • Other carbohydrates pass undigested into the large intestine, where they are digested by intestinal bacteria.
  • Some carbohydrates, such as cellulose, are not digested at all, despite being made of multiple glucose units.

• 3D Plots

  • Figure 1 shows a 3D scatter plot of the fat, non-sugar carbohydrates, and calories from a variety of cereal types.
  • A 3D scatter plot showing fat, non-sugar carbohydrates, and calories from a variety of cereal types
  • An alternative 3D scatter plot showing fat, non-sugar carbohydrates, and calories.

• Carbohydrate Molecules

  • Carbohydrates can be represented by the stoichiometric formula (CH2O)n, where n is the number of carbons in the molecule.
  • Therefore, the ratio of carbon to hydrogen to oxygen is 1:2:1 in carbohydrate molecules.
  • The origin of the term "carbohydrate" is based on its components: carbon ("carbo") and water ("hydrate").
  • Carbohydrates are classified into three subtypes: monosaccharides, disaccharides, and polysaccharides.
  • Carbohydrates serve various functions in different animals.

• Fluid Mosaic Model

  • The fluid mosaic model describes the plasma membrane structure as a mosaic of phospholipids, cholesterol, proteins, and carbohydrates.
  • The proportions of proteins, lipids, and carbohydrates in the plasma membrane vary with cell type.
  • Carbohydrates are the third major component of plasma membranes.
  • These carbohydrate chains may consist of 2–60 monosaccharide units and can be either straight or branched.
  • These carbohydrates on the exterior surface of the cell—the carbohydrate components of both glycoproteins and glycolipids—are collectively referred to as the glycocalyx (meaning "sugar coating").

• Types of Biological Macromolecules

  • Biological macromolecules, the large molecules necessary for life, include carbohydrates, lipids, nucleic acids, and proteins.
  • If we were to string many carbohydrate monomers together we could make a polysaccharide like starch.
  • The carbohydrate monosaccharides (fructose and glucose) are joined to make the disaccharide sucrose.
  • Carbohydrates, proteins, and nucleic acids are built from small molecular units that are connected to each other by strong covalent bonds.