biological molecules Flashcards
monomers
small, building blocks of larger molecules. they can join together through chemical reactions to form polymers. examples include amino acids, nucleotides, and monosaccharides
polymers
polymers are large molecules made up of repeating subunits called monomers
condensation reaction
joins two molecules together with the formation of a chemical bond and involves the elimination of a molecule of water
hydrolysis reaction
hydrolysis reaction breaks a chemical bond between two molecules and involves the use of a water molecule
monomer carbohydrates are made from
monosaccharide
examples of monosaccharides
glucose, galactose and fructose
bond formed by two monosaccharides
glycosidic bond
polymer formed by two monosaccharides
disaccharides
disaccharide formed by condensation of two alpha glucose molecules
maltose
disaccharide formed by condensation of a glucose molecule and a fructose molecule
sucrose
disaccharide formed by condensation of a glucose molecule and a galactose molecule
lactose
two isomers of glucose
α-glucose and β-glucose
polymer formed by condensation reaction of many glucose units
polysaccharide
polysaccharides formed by alpha glucose
glycogen and starch
polysaccharide formed by beta glucose
cellulose
structure and function of glycogen
- alpha glucose
- 1-4 and 1-6 glycosidic bonds
- animals (muscle and liver)
- highly branched (more than starch)
- branches increase SA for hydrolysis back to glucose (ends acted on by enzymes)
- insoluble so won’t impact WP
- compact
structure and function of starch
- alpha glucose
- 1-4 amylose, 1-4 and 1-6 amylopectin
- plants (chloroplasts)
- amylose is unbranched helix
- compact
- amylopectin is branched
- branches increase SA for hydrolysis back to glucose (ends acted on by enzymes)
- insoluble so won’t impact WP
structure and function of cellulose
- beta glucose
- 1-4 glycosidic bonds
- plants (cell wall)
- polymers form long, unbranched, straight chains
- chains held in parallel by hydrogen bonds to form microfibrils
- hydrogen bonds increase strength of cell wall
- insoluble so won’t affect WP
test for reducing sugars
benedict’s reagent
- liquid form of food sample
- benedict’s reagent
- heat in water bath
- colour change from blue to green, yellow, orange or brick red
test for non-reducing sugars (sucrose)
negetive benedict’s test
- add acid and boil
- cool and alkali to neutralise
- add benedict’s reagent and heat
- blue to green, yellow, orange or brick red
test for starch
- iodine
- colour change from orange to blue/black
two groups of lipids
triglycerides and phospholipids
structure of triglyceride
triglycerides are formed by the condensation of one molecule of
glycerol and three molecules of fatty acid
bond formed glycerol and fatty acid (RCOOH)
ester bond
saturated or unsaturated part of a triglyceride
fatty acid
difference between saturated and unsaturated fatty acid
unsaturated have one or more double carbon bond
structure of phospholipid
one of the fatty acids of a triglyceride is
substituted by a phosphate-containing group
properties of triglycerides
- energy storage due to high ratio of C-H bond compared to C bond
- metabolic water source due to high ratio of H:O, oxidised to create H2O
- do not affect WP because they are large and hydrophobic (insoluble)
- low mass so can be stored without increasing mass and preventing movement
properties of phospholipids
- hydrophillic head attracts water because it is charged
- hydrophobic tail repels water and mixes with fat
- two charged regions so are polar
- form phospholipid bilayer
test for lipids
emulsion test
- dissolve sample in ethanol
- add distilled water and shake
- cloudy white emulsion forms