Lipids, Water and Inorganic Ions Flashcards
Describe how to test for lipids in a sample.
- Dissolve solid samples in ethanol
- Add an equal volume of water and shake
- Positive result: milky white emulsion forms
How do triglycerides form?
Condensation reaction between 1 molecule of glycerol & 3 fatty acids forms ester bonds.
Contrast saturated and unsaturated fatty acids.
Saturated:
- only single bonds
- straight-chain molecules have many contact points
- melting point = solid at room temp
- found in animal fats
Unsaturated:
- contain C=C double bonds
- kinked molecules have fewer contact points
- lower melting ooint = liquid at room temp
- found in plant oils
Relate the structure of triglycerides to their functions.
- high energy:mass ratio = high calorific value
- insoluble hydrocarbon chain = no effect on water potential of calls (waterproofing)
- slow conductor of heat = thermal insulation
- less dense than water = buoyancy (aquatic animals)
Describe the structure and function of phospholipids.
Amphipathic molecule: glycerol backbone attached to 2 hydrophobic fatty acid tails & 1 hydrophilic polar phosphate head.
- forms phospholipid bilayer in water = component of membranes
- tails can splay outwards = waterproofing
Compare phospholipids and triglycerides.
- both have glycerol backbone
- both may be attached to a mixture of saturated, monounsaturated & polyunsaturated fatty acids
- both contain elements C, H, O
- both formed by condensation reactions.
Contrast phospholipids and triglycerides.
Phospholipids:
- 2 fatty acids & 1 phosphate group attached to
- hydrophilic head & hydrophobic tail
- used primarily in membrane formation
Triglycerides:
- 3 fatty acids attached
- entire molecule is hydrophobic
- used primarily as a storage molecule
Are phospholipids and triglycerides polymers?
No they are macromolecules.
Why is water a polar molecule?
O is more electronegative than H
Forms O δ- & Hδ+
State 4 biologically important properties of water.
- metabolite/ solvent for chemical reactions
- high specific heat capacity
- high latent heat of vapourisation
- 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 temp
- cohesion-tension of water molecules in transpiration stream
What are inorganic ions and where are they found in the body?
- ions that do not contain carbon atoms
- found in cytoplasm & extracellular fluid
- may be in high or very low concentrations
Explain the role of hydrogen ions in the body.
- high conc of H+ = low (acidic) pH
- H+ interact with H-bonds & 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 haem group in haemoglobin.
Haemoglobin group has binding site to transport 1 mol of O2 around the body in bloodstream
4 haem groups per haemoglobin molecule
Explain the role of sodium ions in the body.
Involved in co-transport for absorption of glucose & amino acids in lumen of gut
Involved in propagation of action potentials in neurons
