1 - Biological Molecules Flashcards
Condensation
Release of water molecule during the joining together of two or more molecules
Hydrolosis
Water molecule is added or used to break bonds
Carbohydrates
Molecules made up of carbon, hydrogen, and oxygen.
Polymers
Contain glycosidic bonds
Energy sources and structural materials
Monosaccharides
Single monomer of a carbohydrate
(CH2O)n where 3 < n < 7
Reducing sugars
Glucose
Fructose
Galactose
Disaccharides
Double sugars formed from two monosaccharides in a condensation reaction
maltose (alpha glucose + alpha glucose)
sucrose (alpha glucose + fructose)
Polysaccharides
Large molecules formed from many monosaccharides
Eg Starch, Cellulose, Glycogen
Glycosidic Bond
Any bond between carbohydrates
Alpha and Beta Glucose
Alpha: Hydrogen above
Beta: Hydrogen below
Amylose
Type of starch
1-4 glycosidic bonds between alpha glucose
Compact helical shape
Amylopectin
Type of starch
1-4 and 1-6 glycosidic bonds between alpha glucose
Highly branched structure
Cellulose
Made up of beta glucose molecules
Long, layered, unbranched chains that are grouped together to form microfibrils
Every other beta glucose is rotated 180 degrees
Hydrogen bonds make cellulose strong and ideal for structural support
Glycogen
1-6 glycosidic bonds between alpha glucose
Less dense and more soluble compared to starch
Similar structure to amylopectin
Lipids
Insoluble in water
Soluble in organic solvents (alcohols, acetate)
Hydrogen, Carbon, Oxygen
High proportion hydrogen, low proportion oxygen
Examples: Triglycerides, waxes, steroids, cholesterol
Can be identified as a carboxylic acid or RCOOH (R group is an acid group at the end of a fatty acid chain which differs in every type of lipid)
Uses:
Energy source
Waterproofing
Insulation
Protection
Triglyceride
Glycerol backbone bonded to three fatty acid chains
OH group in fatty acid bonds with one of the OH groups in glycerol in a condensation reaction
Types of Fatty Acids
Saturated:
Only single bonds
Unsaturated:
Double bonds between carbon atoms
Can be either cis (hydrogen above) or trans (hydrogen above and below)
Phospolids
Similar to triglycerides
Only two fatty acid chains
Polar phosphate group joined to third hydroxyl group
Tail (fatty acid): Hydrophobic
Head (phosphate): Hydrophilic
Proteins
Diverse group of large and complex polymers made up of long chains of amino acids
Used for:
Structure (tissues, muscles, ligaments, skin)
Catalysts (enzymes)
Signalling (hormones and receptors)
Immune system (antibodies)
Protein Structure
Primary - amino acid sequence (peptide bonds between amino acids formed by condensation reactions)
Secondary - hydrogen bonds within polypeptide chain create alpha helix or beta pleated sheets
Tertiary- complex folding of polypeptide chain due to R-R interactions (hydrophobic, disulfide, ionic)
Quaternary- interactions between polypeptides
Fibrous Proteins
Formed from parallel polypeptide chains held together by cross-links. These form long, rope-like fibres, with high tensile strength and are generally insoluble in water.
Examples:
Collagen
Keratin
Silk
Globular Proteins
Spherical shape caused by tightly folded polypeptide chains
The chains are usually folded so that hydrophobic groups are on the inside, while the hydrophilic groups are on the outside. This makes many globular proteins soluble in water.
Examples:
Hormones
Enzymes
Transport proteins
Benedict’s Test
Add Benedict’s reagent to a sample solution in a test tube
Heat the test tube in a water bath or beaker of water that has been brought to a boil for a few minutes
If a reducing sugar is present, a coloured precipitate will form
Green, yellow, red
Benedict’s Test for Non-Reducing Sugars
Add dilute hydrochloric acid to the sample and heat in a water bath that has been brought to the boil
Neutralise the solution with sodium hydrogencarbonate
Then carry out Benedict’s test as normal
(heat with acid, neutralise, carry out test as normal)
