lipids and water and inorganic ions pmt flashcards
describe how to test for lipids in a sample
1.dissolve solid samples in ethanol
2.add an equal volume of water and shake
3.positive result:milky white emulsion forms
hw do triglyceride form
condensation reaction between. 1 molecule of glycerol and 3 fatty acids form ester bonds
contrast saturated and unsaturated fatty acids
SATURATED
-contain only single bonds
-straight chain molecules have many contact points
-higher melting point=solid at room temperature
-found in animal fats
UNSATURATED
-contain C=C double bonds
-kinked molecules have fewer contact points
-lower melting points=liquid at room temperature
found in plant oils
relate the structure of triglycerides of their functions
-high energy: mass ratio=igh calorific value from oxidation(energy storage)
-insoluble hydrocarbon chain=no effect on water potential of cells&used for waterproofing
-slow conductor of heat=thermal insulation
-less dense than water=buoyancy of aquatic animals
describe the structure and function of phospholipids
amphipathic molecule:glycerol backbone attached to 2 hydrophobic fatty acid tails and 1 hydrophilic polar phosphate head
-forms phospholipid bilayer in water=component of membranes
-trails can splay outwards=waterproofing
compare phospholipids and triglycerides
-both have glycerol backbone
-both may be attached to a mixture of saturated, monounsaturated and polyunsaturated fatty acids
-both contain the elements C,H,O
both formed by condensation reactions
contrast phospholipids and triglycerides
PHOSPHOLIPDS:
-2 fatty acids & 1phosphate group attached
-hydrophillic head & hydrophilic tail
-used primarily in membrane formation
TRIGLYCERIDES:
-3 fatty acids attached
-entire molecules is hydrophobic
used primarily as a storage molecule (oxidation releases energy)
are phospholipids and triglycerides polymers?
no; they are not made from a small repeating unit.They are macromolecules
why is water a polar molecule
O is more electronegative than H, so attracts the electron density in the covalent bond more strongly.
Forms pleated(slight negative charge) and H s+ )slight positive charge)
state 4 biologically important properties of water.
due to polarity&intermolecular H-bonds:
-metabolite/solvent for chemical reactions in the body
-high specific latent heat of vaporisation
cohesion between molecules
explain why water is significant to living organisms
-solvent for polar molecules during metabolic reactions
-enables organisms to avoid fluctuations in core temperature
-cohesion-tension of water molecules in transpiration stream
what are inorganic ions and where they are found in the body
-ions that do not contain carbon atoms
found in cytoplasm and extracellular fluid
-may be in high or very low concentrations
explain the role of hydrogen ions in the body
-high concentration of H+=low (acidic) pH
-H+ ions interact with H bonds and ionic bonds in tertiary structure of proteins which can cause them to denature
explain the role of iron ions in the body
-FE2+ bonds to porphyrin ring to form ham group in haemoglobin
-haem group has binding site to transport 1 molecule of 02,around the body in bloodstream
-4 ham groups per haemoglobin molecule
explain the role of sodium ions in the body
-involved in co transport for absorption of glucose and amino acids in lumen of gut
-involved in propagation of action potentials in neurones
