ISC 11>Content>Unit-4>Biomolecules

Scope of syllabus

Biomolecules: 

• Carbohydrates- General classification and functions of: monosaccharides (glucose, ribose and deoxyribose), disaccharides (maltose, lactose and sucrose), polysaccharides (glycogen, starch, cellulose, inulin, and chitin).
• Proteins- Amino acids – (structure: glycine, alanine, serine); amino acids as zwitter-ion; examples of acidic, basic, neutral, sulphur containing amino acids; essential and nonessential amino acids; levels of protein structure (primary, secondary, tertiary and quaternary); functions of proteins.
• Lipids – classification, structure and functions of fats and oils ​ 

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• Nucleotides and nucleic acids – structure and functions of DNA, types of RNA. Differences between DNA and RNA

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Biomolecules
The molecules occurring in living organisms are called biological molecules.

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Basics of biochemistry

A. Common elements

• Oxygen (O), carbon (C), hydrogen (H), and nitrogen (N) make up 96% of most living organisms.
• Trace elements are elements that are necessary, but present in very small quantities.(1% of the body weight)

1. Sulphur: an important element in some amino acids.
   
2. Calcium: used during nerve impulses 
3. Iron: found in hemoglobin (oxygen transport protein)
4. Sodium: needed for a nerve impulse 
5. Phosphorus: in cell membrane structures and DNA
   

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2. Chemical bonding

• Molecules are made of two or more atoms bonded together through electron interactions.
• A substance made of atoms of different elements is a compound.
• Attractive forces (chemical bonds) hold atoms together in molecules.

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3.  Polarity:  Electrons in a covalent bond may be equally or unequally shared between the atoms

Non-polar covalent bond: 
atoms share electrons evenly

Polar covalent bond: atoms share electrons unequally, so there is a slight difference in charge between the two poles of the bond

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4. Carbon

Why Is Carbon So Important?

• Carbon atoms are versatile and can form up to four bonds (single, double, or triple) and rings..
• Functional groups in organic molecules confer chemical reactivity and other characteristics.
• Functional groups are specific groups of atoms within molecules that are responsible for the characteristic chemical reactions of those molecules
  

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5. Condensation and hydrolysis
Condensation: A chemical reaction in which two molecules combines to form single molecule, with the loss of a small molecule (Water)
Hydrolysis: A reaction in which water is used to split a substance into smaller particles.

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Micromolecules and macromolecules

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Carbohydrates            Lipids               Proteins               Nucleic acids