BIOLOGY - Ch#4
Biological Molecules
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Notes
Introduction
Foods have a mix of different nutrients in them. For the human body to remain healthy, it must
be supplied containing seven groups of substances - carbohydrates, proteins, lipids, vitamins,
mineral ions, fibre, and water.
● Carbon is present in all biological molecules in the form of chains and rings.
● H2O is also present.
● Nitrogen is present sometimes.
● Repeating subunits = monomers held together by chemical bond = polymers
● Proteins = Chains of amino acids
● DNA = Chains of nucleotides
● Polysaccharide = Chains of single sugar
Carbohydrates:
● Collectively called as saccharides.
● Mostly found in starchy foods.
● Provide calories and energy.
● The word itself tells about its composition:
○ Carbo = carbon
○ Hydrate = water
○ Made of just 3 elements - carbon, hydrogen, and oxygen
■ Atoms of hydrogen and oxygen in a ratio of about 2:1, i.e, water (H2O)
Monosaccharides
● A group of carbohydrates called simple sugars
● One sugar molecule
, ● Form the ‘building blocks’ of more complex carbohydrates.
● Glucose is an example of a carbohydrate monomer or monosaccharide.
○ Most important member of the sugar family
○ Can cross the Blood-Brain barrier and nourish the brain
● Fructose is also a monosaccharide.
○ Commonly found in honey, fruits, and root vegetables.
● Galactose
○ Known as milk sugar.
○ Known as milk sugar because it's only found in nature when it links with glucose
to form lactose.
Disaccharides
● Two monosaccharides combine to form a disaccharide.
● Examples of carbohydrates having two monomers include- Sucrose, Lactose, Maltose,
etc.
● Example#1; Lactose:
○ Galactose and glucose link to form lactose
○ Found in milk of mammals, i.e. cow and breasts
● Eg.2; Sucrose:
○ Also called table sugar
○ Disaccharide of glucose and fructose
○ Found in various fruits and vegetables e.g. sugar cane
● E.g3; Maltose:
○ 2 glucose molecules linked together
Monosaccharides and Disaccharides are readily soluble in water; H2O, and are simple.
Polysaccharides (Complex carbohydrates)
● A substance made of a chain of many monosaccharides is called a polysaccharide.
● Complex carbohydrates have two or more sugar molecules, hence they are referred to as
starchy foods.
● In complex carbohydrates, molecules are digested and converted slowly compared to
simple carbohydrates.
● They are abundantly found in lentils, beans, peanuts, potatoes, peas, corn, whole-grain
bread, cereals, etc.
Biological Molecules
___
Notes
Introduction
Foods have a mix of different nutrients in them. For the human body to remain healthy, it must
be supplied containing seven groups of substances - carbohydrates, proteins, lipids, vitamins,
mineral ions, fibre, and water.
● Carbon is present in all biological molecules in the form of chains and rings.
● H2O is also present.
● Nitrogen is present sometimes.
● Repeating subunits = monomers held together by chemical bond = polymers
● Proteins = Chains of amino acids
● DNA = Chains of nucleotides
● Polysaccharide = Chains of single sugar
Carbohydrates:
● Collectively called as saccharides.
● Mostly found in starchy foods.
● Provide calories and energy.
● The word itself tells about its composition:
○ Carbo = carbon
○ Hydrate = water
○ Made of just 3 elements - carbon, hydrogen, and oxygen
■ Atoms of hydrogen and oxygen in a ratio of about 2:1, i.e, water (H2O)
Monosaccharides
● A group of carbohydrates called simple sugars
● One sugar molecule
, ● Form the ‘building blocks’ of more complex carbohydrates.
● Glucose is an example of a carbohydrate monomer or monosaccharide.
○ Most important member of the sugar family
○ Can cross the Blood-Brain barrier and nourish the brain
● Fructose is also a monosaccharide.
○ Commonly found in honey, fruits, and root vegetables.
● Galactose
○ Known as milk sugar.
○ Known as milk sugar because it's only found in nature when it links with glucose
to form lactose.
Disaccharides
● Two monosaccharides combine to form a disaccharide.
● Examples of carbohydrates having two monomers include- Sucrose, Lactose, Maltose,
etc.
● Example#1; Lactose:
○ Galactose and glucose link to form lactose
○ Found in milk of mammals, i.e. cow and breasts
● Eg.2; Sucrose:
○ Also called table sugar
○ Disaccharide of glucose and fructose
○ Found in various fruits and vegetables e.g. sugar cane
● E.g3; Maltose:
○ 2 glucose molecules linked together
Monosaccharides and Disaccharides are readily soluble in water; H2O, and are simple.
Polysaccharides (Complex carbohydrates)
● A substance made of a chain of many monosaccharides is called a polysaccharide.
● Complex carbohydrates have two or more sugar molecules, hence they are referred to as
starchy foods.
● In complex carbohydrates, molecules are digested and converted slowly compared to
simple carbohydrates.
● They are abundantly found in lentils, beans, peanuts, potatoes, peas, corn, whole-grain
bread, cereals, etc.
