Biological Molecules: Lipids+ Water+ Inorganic ions Flashcards
(20 cards)
Describe how to test for lipids in a sample.
- Dissolve solid samples in ethanol
- Add equal volume of water and shake
- Positive result is a white milky emulsion.
(The more lipid/ higher conc. of lipid the more noticable the milky colour will be.)
Give an example of two groups of lipids.
Triglycerides and phospolipids
What saftey precaution should you take when perfoming the emulsion test for lipids?
-Ethanol is flammable, so ensure you do this test away from any open flames
How do triglycerides form?
-Condensation reaction between one molecule of glycerol and three fatty acids forms three ester bonds and releases three molecules of water.
Contrast saturated and unsaturated fatty acids.(All fatty acids contain the same basic structure but the hydrocarbon tail varies. R-group of a fatty acid may be saturated or unsaturated)
Saturated:
-Contain only single bonds
-Straight chained molecules having many contact molecules
-Higher melting points so solid at room temperature
-Found in animal fats
Unsaturated:
-Contains C=C bonds
-Kinked molecules have fewer contact points.
-Lower melting point so liquid at room temperature
- Found in plant oils
Draw the formation of a triglyceride
Relate the structure of triglycerides to their functions.
-High energy to mass ratio= high calorific value from oxidation (energy storage) lots of energy reased when broken down
-Insoluble hydrocarbon chain= no effect on water potential of cells used for water proofing
-Slow conductor of heat= thermall insulation e.g adipose tissue
-Less dense than water= buoyancy of aquatic animals.
Describe function and structure of phospolipids.
Amphipathic molecule: glycerol molecule is attached to two hydrophobic fatty acid tails and hydrophyllic polar phosphate head.
-Forms phospholipid bilayer in water= component of membranes.
-Tails can splay outwards= waterproofing
Compare phospholipids and triglycerides
-Both have a glycerol backbone
-Both contain elements C,H,O
-Both may be attached to a mixture of saturated, monosaturated and polysaturated fatty acids.
-Both formed by condensation reactions
Contrast phospolipids and triglycerides
Phosplipids
-two fatty acids and phospate group attached
-Hydrophyllic head and hydrophobic tail
-Used primarily in membrane formation
Triglycerides
-Three fatty acids attached
-Entire molecule is hydrophobic
-Used priomarily as a storage molecule(oxidation releases energy).
Why is water a polar moelcule?
Oxygen is more electronegative than hydrogen so attracts the electron density in the covelant bond more strongly.
Forms delta negative oxygen and delta positve hydrogen
Are phosplipids and triglycerides polymers?
No as they are not made from small repeating units.They are macromolecules.
Draw a water molecule
State 4 biologically important properties of water.
Due to polarity and intermolecular bonds:
-Metabolite/ solvent for chemical reactions in the body
-High specific heat capacity
-High latent heat of vaporisation
-Cohesion between molecules
Explain why water is important to living organisms.
-Solvent for polar molecuels during metabolite reactions
-Enables molecules to avoid fluctuations in core temperatures
-Cohesion tension of water molecules in transpiration stream
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What are inorganic ions and where are they 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+ means low (acidic) ph
-H+ ions interact with H-bonds and ionic bonds in teritary structure of proteins which can cause them to denature.
Explain the role of iron ions in the body
-Fe2+ ions bind to oxygen in heamoglobin.
When oxygen is bound it becomes Fe3+ till oxygen is released.
-Component of heamoglobin
Explain the role of sodium ions in the body
-Involved in cotransport for absorbtion of glucose and amino acids in lumen of gut
Explain the role of phospate ions in the body
Component of:
-DNA
-ATP
-NAPD
-cAMP
