Chapter 2: Biological Molecules Flashcards
(43 cards)
Test For Starch
Iodine Solution, Turns from Brown -> Blue/ Black.
Test For Proteins
Biuret Reagent, Turns from Blue -> Purple if protein is present.
Test For Reducing Sugars
Add Benedicts Reagent to sample, heat it up, if colour change from blue to brick red, reducing sugar is present. Colour may vary from red (highest conc) to orange to yellow to green to blue (lowest conc).
Test For Lipids
Ethanol Emulsion Test, Add ethanol to sample and mix it up. If cloudy white emulsion forms, lipids are present.
Test For Non Reducing Sugars
Add Dilute HCl to sample to hydrolyze the non reducing sugar, then heat up and then add Na2CO3 to neutralize. Add Benedicts Reagent, Heat up and observe colour change.
α-glucose and β-glucose
Structural Isomers
The difference is the position of the hydroxyl group at the first carbon atom. In α-glucose the OH is below the ring, in β-glucose, the OH is above the ring.
Monomer
A monomer is a small, single unit or molecule that can join together with other similar or different molecules to form a larger structure, called a polymer.
Polymer
A polymer is a large molecule composed of many repeated subunits (monomers) linked together through covalent bonds.
Macromolecule
A macromolecule is a very large molecule, typically composed of thousands of atoms, formed by the polymerization of smaller units (monomers)
Monosaccharide
A monosaccharide is the simplest form of carbohydrate and consists of a single sugar unit. It cannot be hydrolyzed into simpler sugars.
Disaccharide
A disaccharide is a carbohydrate composed of two monosaccharide units joined together by a glycosidic bond
Polysaccharide
A polysaccharide is a carbohydrate made up of many monosaccharide units linked together, forming long chains.
Condensation Polymerisation
A chemical reaction where two or more monomers combine to form a larger polymer, releasing a small molecule (often water) as a byproduct.
Hydrolysis
A chemical reaction where water is used to break down a compound into smaller units, reversing condensation polymerization.
Reducing Sugar Examples
Glucose, Fructose, & Maltose
Non Reducing Sugar Example
Sucrose
Glycosidic Bond
A covalent bond formed between two monosaccharides through a condensation reaction, resulting in the release of water.
Example :
Sucrose (glucose + fructose) has an α-1,2-glycosidic bond.
Maltose (glucose + glucose) has an α-1,4-glycosidic bond.
Structure : (- O -)
Molecular Structure of Starch
Starch consists of two components: Amylose, a linear polymer of α-glucose with α-1,4-glycosidic bonds, and Amylopectin, a branched polymer with both α-1,4 and α-1,6-glycosidic bonds.
Function of Starch
Serves as the primary energy storage polysaccharide in plants, allowing for compact storage and easy breakdown of glucose when energy is needed.
Molecular Structure of Glycogen
A highly branched polymer similar to amylopectin, consisting of α-glucose units linked by α-1,4 and α-1,6-glycosidic bonds, with branches occurring every 8-12 glucose units.
Function of Glycogen
Found in Liver : Primary energy storage polysaccharide in animals, allowing for rapid mobilization of glucose for quick energy needs, such as during exercise.
Molecular Structure of Cellulose
A linear polymer of β-glucose linked by β-1,4-glycosidic bonds, forming strong hydrogen bonds with adjacent chains to create microfibrils.
Function of Cellulose
Provides structural support to plant cell walls, maintaining cell shape and integrity, and contributing to the strength of plant tissues.
Triglycerides
Non-polar and hydrophobic molecules. Composed of one glycerol molecule and three fatty acids. Formed through a condensation reaction where each fatty acid forms an ester bond with the glycerol.
