Topic 1 - Biological molecules Flashcards
Hydroxyl group OH
This is a simple chemical group consisting of oxygen creating a covalent bond with hydrogen. ‘R’ can be anything and varies
Carboxyl group COOH
Made of one carbon atom boded with hydroxide and oxygen and ‘R’ where there are two bonds with oxygen .
Amine group NH2
Here, the nitrogen is bonded with 2 hydrogen atoms and “R” which can vary
Alpha glucose
complex molecule that has 6 carbon atoms, type of hexose sugar. It can form the polymer carbohydrate - e.g. starch, cellulose
Beta glucose
Complex molecule, the same as alpha glucose but the OH and H swap in the first carbon atom in the sequence
Fatty acid
Complex molecule, contains a carboxyl group on its end. It can be unsaturated (has double bonds) or saturated (no double bonds). It creates lipids
Amino acid
Complex molecule, contains amine group and carboxyl group with a carbon in the middle, bonded with the amine group, carboxyl group, hydrogen and ‘R’. It forms proteins
Ribose
Complex molecule, type of pentose sugar.
Creates RNA and DNA
Hydrogen bond
A hydrogen bond between water occurs when a slightly negatively charged water molecule is attracted to a slightly positively charged hydrogen atom in a water molecule
Monosaccharide
Single sub unit of sugar, for instance glucose, which can join together through condensation reaction to form a disaccharide or a polysaccharide
Disaccharide
A disaccaride is 2 monosaccharides joined together through a condensation reaction. A disaccharide can split back into 2 monosaccharides through a hydrolysis reaction
Polysaccharide
Many monosaccharides joined together through a condensation reaction. A polysaccharide can be broken down into a disaccharide and then broken again into monosaccharides through a hydrolysis reaction
Condensation reaction
Involves the removal of water in order for two monosaccharides to join together
Hydrolysis reaction
Involves the addition of water to a disaccharide or polysaccharide in order to turn back into a monosaccharide
Reducing sugar
Easily oxidised - a sugar that donates electrons to other chemicals e.g. monosaccharides, maltose and lactose
Non reducing sugar
Cannot be easily oxidised - a sugar that accepts electrons from other chemicals. E.g. sucrose
Glycosidic bond
The covalent bond formed between two monosaccharides during a condensation reaction
Test for reducing sugars (Benedicts reagent)
1) Add Benedicts reagent to substance
2) Orange/red = reducing sugar present
Test for non reducing sugars
1) add HCL to substance and warm
2) Add sodium hydroxide (neutralise HCL)
3) Test final substance with Benedicts reagent
Test for starch (Iodine)
1) Put iodine into substance
2) Iodine turns blue/black (starch present)
Sweet flavour
Monosaccharides:
Glucose, galactose, fructose
Storage polysaccharides
Glycogen, starch
(insoluble, compact, osmotically inactive)
Structural polysaccharides
Cellulose
(insoluble, strong, freely permeable to solutes/solvents)
Sucrose
Glucose + Fructose
Lactose
Galactose + glucose
Maltose
Glucose + glucose
Cellulose
Source: plants (cell wall)
Subunit: b-glucose
Bonds: 1,4 alternating glycosidic bonds
Branches: no
Shape: straight chains
Function: support cell
Info: alternative bonding causes chains of cellulose to line up parallel to each other. They’re linked by weak hydrogen bonds which forms intermolecular forces which are collectively very strong. Intermolecular forces bundle up to make microfibrils. Cellulose is insoluble
Starch (amylose)
Source: plants
Subunit: a-glucose
Bonds: 1,4 glycosidic bonds
Branches: No
Shape: helical
Function: storage
Info: No alternative bonding so molecules bend, creating spiral shape which is held by hydrogen bonds. Amylose is insoluble
Starch (amylopectin)
Source: plants
Subunit: a-glucose
Bonds: 1,4 and 1,6 glycosidic bonds
Branches: yes
Shape: compact, branched
Function: storage
Info: many branches, so amylopectin folds compactly which makes it easier to store molecules. Its insoluble
Release of glucose in amylose vs amylopectin
Amylose = slow due to few terminal molecules, slower hydrolysis and production of glucose
Amylopectin = fast due to many terminal molecules on branches, faster hydrolysis and production of glucose
Glycogen
Source: animals
Subunit: a-glucose
Bonds: 1,4 and 1,6 glycosidic bonds
Branches: yes
Shape: compact, branched
Function: storage of glucose in body
Info: glycogen found in liver and muscles, where rate of respiration is regularly raised very rapidly
Lipid
Fatty acid
Fatty acid chain
Long hydrocarbon chain
Carboxyl terminal group (COOH)
Unsaturated acid chain
long hydrocarbon chain
carboxyl terminal group (COOH)
Unsaturated fatty acid characteristics
Liquid at room temperature
Oils
One or more double C-C bond present, causing kinks in the fatty acid chain