2.1.2 Biological Molecules Flashcards
Test for starch
Iodine test, turns blue-black
Test for protein
Biuret test, turns purple
Structure and function of amylopectin
Helical shape so is compact and tightly packed.
Large insoluble molecule so does not affect water potential.
Branched with alpha 1-4 and 1-6 glycosidic bonds so glucose is easily released.
Large molecule so cannot leave cell/cross plasma membrane.
Test for lipids
Ethanol, mix with sample.
Then add water and mix.
If solution turns milky white then it contains lipids.
Functions of lipids in animals.
Energy source/store, has high energy value and is compact so minimises mass.
Thermal insulation, poor heat conductor, minimises heat loss from body.
Waterproofing, non-polar, hydrophobic and insoluble.
Buoyancy, loess dense than water.
Protection around organs, elastic, and forms a protective layer around organs, helps to cushion them from external forces.
How does the change to one amino acid affect the structure of a protein.
There’s a change in the amino acid sequence in the primary structure.
This causes a change in the disuflide/ionic/hydrogen bonds between R groups.
Therefore causes a change in the protein tertiary structure.
Properties of collagen
Strong hydrogen bonds between triple helix structure provides tensile strength.
Stable protein and forms connective tissue.
Insoluble in water so it provides structural support.
Test for glucose
Benedict’s solution blue/turquoise
Green- low amount of reducing sugar.
Turns red/orange - high amount of reducing sugar
DNA extraction from plant cells by precipitation method
Sample is ground to break down cell walls
Mixed with detergent to break down cell membrane
Salt added to break hydrogen bonds with DNA
Protease enzymes added to break down associated proteins
Ethanol added to top off sample to precipitate DNA out
