Bio Molecules Flashcards
How do hydrogen bonds form between water molecules
Water is polar: O more electronegative than H, so attracts electron density in covalent bond more strongly. Forms O (slightly negative) and H (slightly positive)
Intermolecular forces of attraction between lone pair on O - of one molecule and H + on an adjacent molecule
State 7 biologically important properties of water
Reaches maximum density at 4 C
High surface tension
Incompressible
Metabolite for chemical reactions in the body
High specific heat capacity
High latent heat of vaporisation
Cohesion between molecules
Why is incompressible nature of water important for organisms
Provides turgidity to plant cells
Provides hydrostatic skeleton for some small animals e.g. earthworms
Explain why ice floats on water. Why is this important for organisms?
Ice is less dense than water because H bond hold molecules in fixed positions further away from each other
Insulated water in arctic climates so aquatic organisms can survive. Water acts as a habitat
Why is the high surface tension of water important for organisms
Slows water loss due to transpiration in plants
Water rises unusually high in narrow tubes, lowering demand on root pressure
Some insects can skim across the surface of water
Why is water an important solvent for organisms
Polar universal solvent dissolves and transports charged particles involved intra and extra cellular reactions
Why are the high specific heat capacity and latent vaporisation of water important for organisms
Acts as temperature buffer which enables endotherms to resist fluctuations in core temperature to maintain optimum enzyme activity
Cooling effect when water evaporates from skin surface as sweat/ mouth when panting
Describe the structure of alpha and beta glucose
Both hexose monosaccharides of 6 carbon with ring structure
Beta glucose has the hydroxide flipped
Properties of alpha glucose
Small and water soluble = easily transported in bloodstream
Complementary shape to antiport for co-transport for absorption in gut
Complementary shape to enzymes for glycolysis = respiratory substrate
Structure and function of starch
Storage polymer of alpha glucose in plant cells
Insoluble = no osmotic effect on cells
Large = does not diffuse out of cells
Structure of amylose
1,4 glycosidic bonds
Helix with intermolecular H-bonds = compact
Structure of amylopectin
1,4 and 1,6 glycosidic bonds
Branched = many terminal ends for hydrolysis into glucose
Structure and function of glycogen
1,4 and 1,6 glycosidic bonds
Branched = many terminal ends for hydrolysis
Insoluble = no osmotic effect and does not diffuse out of cells
Compact
Describe the structure and functions of cellulose
Polymer of beta glucose gives rigidity to plant cell walls (prevents bursting under turgor pressure, holds stem up)
1,4 glycosidic bonds
Straight-chain, unbranched molecule
Alternate glucose molecules are rotated 180
H-bond cross links between parallel strands from microfibrils = high tensile strength
