Carbohydrates

• Monosaccharides are simple sugars that cannot be broken down into simpler molecules by hydrolysis.
• Carbohydrate is the most abundant organic compound on earth.
• Carbohydrates constitute 75% by mass of dry plant materials.
• Plants have two main uses for the carbohydrates they produce: cellulose and starch.
• A carbohydrate is a polyhydroxy aldehyde, polyhydroxy ketone, or a compound that yields those upon hydrolysis.
• Cellulose is a carbohydrate that serve as structural elements.
• Starch is a carbohydrate that provides energy for the plants.
• Glucose has an aldehyde group therefore it is considered as polyhydroxy aldehyde.
• Fructose has a ketone group therefore it is considered as polyhydroxy ketone.
• Monosaccharide is a carbohydrate that contains a single polyhydroxy aldehyde or polyhydroxy ketone.
• Pure monosaccharides are water-soluble, white, and crystalline solids.
• A carbohydrate that has three to seven carbon atoms is a monosaccharide.
• Oligosaccharide is a carbohydrate whose molecules are composed of a relatively small number of monosaccharide units ranging from two to ten.
• Disaccharide is a common type of oligosaccharide.
• Disaccharide is a carbohydrate that is formed by the condensation of two monosaccharides.
• Sucrose and Lactose is a form of a disaccharide.
• Sucrose is also called table sugar.
• Lactose is commonly known as milk sugar.
• A polysaccharide is a polymeric carbohydrate that contains several thousand monosaccharide units.
• Examples of a polysaccharide are cellulose and starch.
• Most monosaccharides exist in two forms; left-handed and right-handed.
• Mirror image is a reflection of an object in a mirror.
• Superimposable and non-superimposable mirror images are types of mirror images.
• Superimposable mirror image refers to images that coincide at all points when the images are laid upon each other.
• Non-superimposable mirror image refers to images that do not coincide when laid upon each other.
• Chiral center refers to an atom that has four different groups.
• If mirror images are not superimposable it refers to chiral molecules.
• Achiral molecules have no chiral center and are superimposable.
• Glyceraldehyde is an example of chiral monosaccharide.

  
• Monosaccharides may contain more than one chiral center.
• The body's response to the right-handed form of the hormone epinephrine is 20 times greater than in the response to the left-handed monosaccharides.
• Plants produce only right-handed monosaccharides.
• Human hands are example of non-superimposable mirror images.
• Stereoisomers are isomers that have the same molecular and structural formulas but differ in the orientation of atoms in space.
• Structural features that generate stereoisomers:

  1. presence of chiral center in a molecule
  2. presence of ''structural rigidity'' in a molecule
• There are two types of stereoisomers: enantiomers and diastereomers.
• Structural rigidity is caused by the restricted rotation of chemical bonds.
• Enantiomers are stereoisomers whose molecules are non-superimposable mirror images of each other.
• Diastereomers are stereoisomers whose molecules are not mirror images of each other.
• Cis isomers are molecules with the same connectivity of atoms. They feature the same side groups placed on the same side of a double bond.