Organic Chemistry

Projects

Properties of Water

Solutions

Buffers

Organic Chemistry Facts

Elements
Organic Groups
Proteins
Carbohydrates
Lipids
Nucleic Acids

Organic Chemistry Sites

Protein Structure and Function. Univ. Wisco.
Carbohydrate Structure and Function. Texas A&M University.
Lipid Structure and Function. Texas A&M University.
Nucleic Acid Structure. Univ. Wisco.
Atoms, Molecules, Water, pH. Clermont College.
pH Regulation During Excercise. Washington Univ.

References:

Biology, 5th ed.. Campbell, Reece, and Mitchell . Benjamin/Cummings, Publ. 2001.

Chemistry and The Living Organism. Bloomfield, Molly M. John Wiley & Sons. 1977.


Return SAS Home
e-mail Kevin C. Hartzog

Organic Moleucles


Carbohydrates:

Elements: C, H, and O.

Function: Energy, structure

Carbohydrates are sugars and starches. The most basic structure consist of 3-6 carbons, but we are going to concentrate upon sugars that form a either a pentagon ring (5-carbon sugars) or a hexagon ring (6-carbon sugars). These sugars are named pentoses and hexoses respectively. The sufix –oses refers to sugar, and prefix refers to the number of carbons. One corner of the ring has an oxygen, so that one carbon group lies outside of the ring. Attached to each carbon is a hydroxyl group, and a hydrogen. If you said that carbohydrates had a primary structure, akin to proteins, it would be the order of the sugars, the pentoses and the hexoses. The simplest sugars are monosaccharides (mono–: one; –saccaharides: sugar). Among the hexoses, sugars having six carbons, there are glucose, galactose, and fructose. Both glucose and galactose have very similar structures, and only differ in the arrangement of on hydroxyl group on the 4th carbon. Fructose looks more like glucose than galactose, but it differs from glucose by having a hydroxyl group on the 1st carbon, with its 2nd carbon having the double bond with oxygen.

Four common monosaccharide hexoses (simple structure)

Glucose

Galactose

Fructose

Simple diagram of glucose, galactose, and fructose not showing the hexagon shape.

 

Four common monosaccharides hexoses (ring structure)

Glucose

Galactose

Fructose

Simple diagram of glucose, galactose, and fructose showing the hexagon shape.

Two common pentoses found in living organisms are ribose and deoxyribose. Ribose and deoxyribose differ in that ribose has a hydroxyl group attached to its 2nd carbon, while deoxyribose has two hydrogens.

Two common monosaccharides pentoses (ring structure)

Ribose

Deoxyribose

 

Two sugars bonded together for the next simplest sugar, disaccaharides (di–: two; –saccaharides: sugars). Two common disaccharides are lactose, milk sugar, and sucrose, table sugar. Lactose is found in mammals milk, made in the mammary glands from glucose and galactose. Sucrose is found in fruits vegetables, and honey, and is made from glucose and fructose.

Two common disaccharides (ring structure)

Lactose

Sucrose

 

The largest carbohydrates are polysaccharides (poly–: many; –saccaharides: sugars). Polysaccharides are long chains of sugars, bonded together. Two common polysaccharides are starch and cellulose. Both polysaccharides are made from long chains of glucose, but they differ in how those glucose molecules are bonded together. In starch, glucose are linked by an a (1-4) bond, while in cellulose, glucose are linked by a b (1-4) bond. In both, the 1st carbon of one glucose is bonded to the 4th carbon of the next glucose molecule. But how those carbons bond differ by where they hold onto each other. Not all polysaccharides are made merely of chains of sugars. Some, like glycogen, have many branches of sugars running off of a main branch.

Two common polysaccharides (ring structure)

Starch (amylose)

Cellulose

 

Glycogen

 

Polysaccharides provide mid-term energy storage and structural components to organisms. Starch is used to store energy in plant cells. In plant cells, you can seen starch granules in some organelles. Glycogen forms similar midterm storage in animals. In mammals, glycogen takes up 5% of the liver by weight, and 0.5% of muscles by weight. Cellulose is a sturdy molecule that’s insoluble in water, forming the main structural fibers for plant cells' walls.