lipids

Question 1

what are lipids made from

Answer 1

Lipids are biological molecules that contain the elements carbon (C), hydrogen (H), and oxygen (O). However, lipids contain a much lower proportion of oxygen than carbohydrates.

Question 2

triglycerides

Answer 2

have one molecule of glycerol with three fatty acids attached to it. fatty acid molecules have long tails of hydrocarbons. the tails are hydrophobic which makes lipids insoluble in water.

Question 3

fatty acids

Answer 3

consist of the basic structure but the hydrocarbon tail varies, two kinds of fatty acids -saturated and unsaturated difference is in the hydrocarbon tails

Question 4

saturated fatty acids

Answer 4

dont have any double bonds between their carbon atoms, the fatty acid is saturated with hydrogen

Question 5

unsaturated fatty acids

Answer 5

do have double bonds between carbon atoms, cause the chain to kink

Question 6

triglyceride formation

Answer 6

formed by condensation reactions, an ester bond forms between the two molecules, releasing a molecule of water= condensation reaction, happens twice more to form a triglyceride

Question 7

phospholipids

Answer 7

lipids found in cell membranes are phospholipids, phospholipids are similar to triglycerides except one pf the fatty acid molecules is replaced by a phosphate group. the phosphate group is hydrophilic, the fatty tails are hydrophobic. this is important in the cell membrane.

Question 8

properties of triglycerides

Answer 8

• mainly used as energy storage molecules, theyre good for this because the long hydrocarbon tails of the fatty acids contain lots of chemical energy, released when broken down. because of these tails lipids contain twice as much energy per gram as carbohydrates.
• insoluble in water, don’t affect water potential of cells and don’t cause water to enter cells by osmosis.
• triglycerides bundle together as insoluble droplets in cells because fatty acid tails are hydrophobic, the tails face inwards, shielding themselves from water with glycerol heads

Question 9

properties of phospholipids

Answer 9

make up the bilayer of cell membranes - controls what enters and leaves the cell. phospholipid heads are hydrophilic and their tails are hydrophobic, form a double layer with their heads facing out towards the water on either side. the centre of the bilayer is hydrophobic so water soluble substances cant easily pass through it. the membrane acts as a barrier for those substances.

Question 10

emulsion test for lipids

Answer 10

shake the test substance with ethanol for about a minute, then pour the solution into water. any lipid will show up as a milky emulsion, the more lipid there is the more noticeable the milky colour will be