lipids Flashcards
- to learn the chemical nature and properties of lipids - to understand how these relate to their function - to be able to recall the different classes of lipids, including fatty acid, phospholipids, sterols , triglycerides and waxes - to understand what osmosis is and how it impacts cells
what is a lipid?
- insoluble molecule (doesn’t dissolve in water)
What are the functions on lipids (name 5)
- energy storage
- cell membrane structural components
- hormones, vitamins + vitamin absorption
- insulation- helps regulate body temp
- protection- fat acts as shock absorber
what can lipids be?
- hydrophobic or amphipathic
what is meant by hydrophobic?
- fully insoluble in water
what is meant by amphipathic?
- water soluble and water insoluble groups on one molecule ; molecule has both polar and non polar regions
what is the hydrophilic head?
- polar head and is water loving
what is the hydrophobic tail?
- non polar ; water hating
what can lipids can be classified as?
- derived from fatty acids such as phospholipids + triglycerides
- derived from sterol such as cholesterol and oestrogen
what chemical group do fatty acids have?
- carboxyl group (o-c=o)
what can fatty acids be?
saturated or unsaturated
what is meant by a saturated fatty acid?
- no double bonds present; has maximum number of hydrogen bonds
what is meant by unsaturated fatty acids?
- has at least one double bond; therefore doesn’t have maximum number of hydrogen bonds
how many structures do unsaturated fatty acids have and why?
- 2 structures as rotation around c=c bond is not allowed
- can be cis –> group on same side of c=c bond
- can be trans–> group on opposite sides of c=c bond.
how does the length of the chain affect melting point?
- longer chain = higher mp because longer carbon chains will experience stronger London forces (Van Der Wals)
- this means there is more attraction between lipids and so more energy is required to break/ overcome them.
how does the cis configuration lower the mp?
- double bond lowers mp; disrupts the long straight chains which leads to ‘kinks’ in the chain therefore there is less attraction and so less energy required to overcome the attraction
what are triglycerides?
- has 3 fatty acid chains + glycerol
- undergoes esterification to form triglyceride + water
- fatty acids are joined by ester bonds (-c=o-r)
what is the function of triglycerides?
- energy storage = energy rich and packs up easily
- buoyancy = low density, changes with temp
- thermal insulation = fats don’t conduct heat well , therefore prevents heat loss
what is the hydrophillic head made of?
PO4- and glycerol group
what is the hydrophobic tail made of?
- saturated and unsaturated fatty acids
how can you describe the cell membrane as?
- a fluid membrane
why is the cell membrane fluid?
- allows water to pass through and can adapt its shape and movement to different conditions
what is osmosis?
- occurs across the cell membrane
- movement of water molecules from a solution of high concentration of water to a solution with low water concentration —> done via partially permeable membrane
Is osmosis passive or active transport?
- passive transport ; water moves to hypertonic area
what is hypotonic and what happens?
- fewer solutes outside of the cell; causes solvent to move into cell which then swells and can burst
what is meant by isotonic?
- equal solute concentration inside and out of cell
what is meant by hypertonic?
- more solutes outside of the cell
what are waxes?
- long chain alcohols and fatty acids; high mp compared to triglycerides
- used for energy storage by marine creatures
what is a sterol??
- basis for a number of lipids
what does sterol contain?
- polar and non polar components—-> amphipathic
- has a carbon ring
- no rotation around a carbon bonds
what are steroid hormones?
- they are derived from sterol and acts as a cellular messenger
what are water soluble vitamins?
- vitamin B class and vitamin C
what are fat soluble vitamins?
- vitamin A,D,E,K
- requires fats to be absorbed into the body
what is vitamin A for?
- retinol; important for skin cells and vision
what is vitamin D important for?
- lacking this will cause rickets
what is vitamin E for?
- To help maintain healthy skin and eyes; strengthens the immune system
what is vitamin K for?
- Required for blood clotting; can be used as a treatment for anticoagulant (blood thinner)
