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Cell Molecules Part 2 - Organic Molecules

Cell Molecules Part 2 - Organic molecules:

Chemical which contains carbon and hydrogen bond are called organic molecules. They are Carbohydrates, lipids, proteins, nucleic acids etc. They are present in protoplasm and combines with O, P, N and S over and above C and H.

Carbohydrates:

Formula – Cn (H2O) m

Types of carbohydrates:

  1. Monosaccharide:
    • Formula – (CH2O)n, value of n lies between 3 to 8
    • Simple carbohydrates
    • Contains carbonyl group (C=O)
    • Sweat in taste and soluble in water
    • Helps in energy transformation process
    • Enters in cell very easily.
    • Example – Glucose, Galactose, Ribose, Deoxyribos
  2. Disaccharides:
    • Formula – Cn(H2O)n-1
    • Two monosaccharide joins by glycosidic bond and forms disaccharides.
    • Sweat in taste and soluble in water
    • Cannot enter in cell directly.
    • Example – sucrose, maltose, lactose
  3. Polysaccharides
    • Formula – (C6H10O5)n
    • Large number of monosaccharide joins by glycosidic bond and forms a long chain called as polysaccharides.
    • Example – starch, glycogen, cellulose

Biological importance of carbohydrates:

  • Useful in energy transformation process
  • Helps in metabolism of cells and constitution of tissues
  • Helps in respiration process.
Lipids:

They are oily and viscous molecules. They are insoluble in water and soluble in organic solvents like benzene, chloroform and ether.

Types of lipids:

  • Simple lipids:
·  They are made up of alcohol and fatty acids.
·  Example – triglycerides – one molecule of alcohol (glycerol) and three molecules of fatty acids
·   Each fatty acids contains carbon witch binds with hydroxyl group of alcohol by ester bond and releases water molecules
·  Fatty acids are of two types – long chain fatty acids (more than 8 carbon atom) and short chain fatty acids (2 to 8 carbon atom)
·  Fatty acids can be either saturated or unsaturated.
·  Saturated fatty acids contains single between all carbon atom and cannot accept new hydrogen atoms.
·  Unsaturated fatty acids contain double bond between nearby carbon at one or more places and accepts new hydrogen atom.
·  Saturated fatty acids are present in solid fats and unsaturated fatty acids are present in liquid oils.


  • Complex lipids:
·  They are made up of alcohol, fatty acids and additional non-lipid constituent.
·  They are named on based of their non-lipid constituent.
·  Example – Glycolipids – carbohydrate
Phospholipids – phosphate
Lipoprotein – protein


  • Steroids:
  They are made up of only alcoholic part and called as sterols.
  They do not contain fatty acids
  Example – cholesterol, testosterol, progesterone


Biological importance of lipids:

  • It releases energy which is double than the carbohydrates
  • It stores food in form of fat and oils
  • It acts as a solvent for fat soluble vitamins like A, D, E, and K.
  • It helps in formation of enzymes and hormones
  • Phospho-lipids are used in formation of plasma-membrane and membranes of organelles.
  • Steroids are the important constituents in plasma-membrane and present in some hormones.
  • Lipids form an insulating layer around nerve fibers or under the skin and provide protection.

Self study:

Example-1: Which of the following is the example of carbohydrates?
a)  Glucose
b)  Sucrose
c)  Glycogen

d)  All of above

Answer: All of above examples are different types of carbohydrates.

Example-2:  Polysaccharide contains …………between large umber of monosaccharide molecules.
a) 
Glycosidic bond
b)  Ester bond
c)  Hydrogen bond
d)  Alcoholic bond

Answer: Polysaccharide contains glycosidic bond between large umber of monosaccharide molecules.


Example-3: Lipids are soluble in ………………
a)  Physiological solvents
b)  Inorganic solvents
c) 
Organic solvents
d)  Water

Answer: Lipids are soluble in organic solvents.


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