Compounds
Organic & Inorganic Compounds
There is no single "official" definition of an organic compound. Some textbooks define an organic compound as one that contains one or more C-H bonds. Some says C-C bonds should be present. Others state that if a molecule contains carbon it is organic.
The "C-H" definition excludes compounds that are historically and practically considered organic. Neither urea nor oxalic acid is organic by this definition.
So we don’t need to indulge into this vast argument. In short most carbon-containing compounds are organic, and almost all organic compounds contain at least a C-H bond or a C-C bond. A compound does not need to contain C-H bonds to be considered organic (e.g., urea), but many organic compounds do.
All compounds except organic compounds are inorganic compounds. Some says inorganic compounds are synthesized by geological system and they don’t have biological origin but some minerals have biological origins.
Organic Compounds are responsible for life on this earth. We will discuss some organic compounds and their role in living system.
These are -
- Carbohydrates
- Lipids
- Proteins
- Enzymes
- Hormones
- Nucleic Acids
- Vitamins
In this article we discuss carbohydrates.
Carbohydrates
Carbohydrates are hydrates of carbon always in the form of
Cx(H2O)y
But all compounds in this form are not carbohydrates. There are some exceptions also. For example
Formaldehyde (HCHO or CH2O) and Acetic acid (CH3CooH or C2H4O2)
These compounds also maintain the above format but these are not carbohydrates.
On the contrary 2-deoxiribose (C5H10O2) is a carbohydrate but does not maintain the above format.
In carbohydrates hydrogen to oxygen ratio is always 2:1. Carbohydrates are oxidized in the cells to release energy. Examples of carbohydrates are sugars, starch, and cellulose.
Carbohydrates are of two types.
| Sugars | Polysaccharides |
|---|---|
|
|
Sugars
Sugar can further be classified into monosaccharide and Disaccharides.
Monosaccharide
These are the simplest form of carbohydrate and hence cannot be further divided into smaller carbohydrates like other carbohydrates. They have a suffix –ose. General formula of a monosaccharide is C6H12O6 but exceptions are also there. Most important are pentose and Hexose. Pentose sugars have 5 carbon and hexose sugars have 6 carbon.
Three simple sugars are-
1. Glucose
Most common and simplest sugar found in organisms. It is considered fuel for living system.
2. Fructose
It is the sweetest of all the sugars. Common in plants and is popularly called fruit sugar. If any fruit or vegetable tastes sweet it is because of fructose.
3. Galactose
Simple sugar found in milk
RNA is made up of Ribose which is a monosaccharide.
DNA is made up of Deoxyribose which is also a monosaccharide.
Ribulose is also a monosaccharide which is responsible for CO2 fixation in photosynthesis.
Disaccharides
These are also called double sugar. General formula is C12H22O11. There are three disaccharides.
Sucrose
This is the sugar that we use in our daily life. It is obtained from sugarcane. It is made up of two simple sugars (Glucose + Fructose).
Lactose
It is also called milk sugar. It is made up of two monomers (Glucose + Galactose).
Maltose
It is an intermediate product during the digestion of carbohydrates and made up of two monomers of Glucose (i.e., Glucose + Glucose).
Polysaccharides
These are carbohydrates having more than 2 monomers (simple sugar). Do not confuse this with oligosaccharides. Oligosaccharides are subset of polysaccharides. Oligosaccharides are nothing but polysaccharides mainly having 3-to-9 monomers or simple sugars. Some refer polysaccharides are carbohydrates having more than 10 monomers.
It can further be classified into storage polysaccharide and structural polysaccharide.
Storage Polysaccharides
These are starch and glycogen.
Starch
These are stored carbohydrates in plant. These are stored in a specialized cell called parenchymatous cell. It has general formula (C6H10O5)n. Startch are of two types Amylose and Amylopectin.
1. Amylose
It is straight chain glucose polymer.
2. Amylopectin
It is branched chain glucose polymer. Don’t confuse amylopectin is a carbohydrate not a protein.
Glycogen
This is the form in which animals store their carbohydrates. Glycogens are branched chain glucose polymer. It is mainly stored in liver. Some are also stored in muscles.
Structural Polysaccharides
These are cellulose and chitin.
Cellulose
These are polymers of glucose. Cell wall of plants and capsule of bacteria consist of cellulose. These are not digested in our food canal but acts as roughage (roughage are substances which helps in retaining water in our body) as these are fibrous and absorb lot of water and retains it. Vegetable, food, corn, dalia are sources of roughage. Cabbage is best source of roughage. DNA paper used for blotting/ fixing is made up of nitrocellulose.
Chitin
It is a nitro glucose polymer. Hard covering of insects and fungus is consisting of chitin. It is similar to cellulose. Because both contributes structure and strength and protect the organism.
Metabolism of Carbohydrates
Carbohydrate metabolism denotes the various biochemical processes responsible for the formation, breakdown and inter conversion of carbohydrates in Living Organisms.
Anabolism
Photosynthesis
It is responsible for starch formation. Here glucose molecules combine together to form starch.
Glucose (many molecules) --photosynthesis à Starch
Glycogenesis
It is responsible for glycogen formation. Here glucose molecules combine together to form glycogen. Hence it reduces glucose concentration.
Glyconeogenesis
When glucose is formed from non-carbohydrate molecules it is called glyconeogenesis. Here new formation of glucose is coming into existence so neo (new) is there with the name.
Catabolism
Glycolysis
It is breakdown of glucose. Hence results in lower concentration of glucose in the body.
Glycogenolysis
Glycogen breakdown is called glycogenolysis and glucose is produced. Hence it is responsible for higher concentration of glucose in body.