2.2 Lipids Flashcards
What are lipids?
Molecules found in fats and oils
What are the functions of lipids?
•Source of energy, broken down by respiration
•Protection and energy store e.g. adipose tissue, under the skin and around internal organs such as kidneys to protect organs from injuries
•Used as waterproofing e.g oils which coat the feathers of aquatic birds
•Major part of the structure of membranes
•Insulation
•Buoyancy- because fat is less dense than water, it is used by aquatic mammals to help them float
What are the two main categories of lipids?
Triglycerides and phospholipids
What is the structure of tryglycerides?
•Contains a molecule of glycerol bonded to three fatty acid molecules
What is the structure of fatty acid molecules?
•Carboxyl group at the end
•Rest of the molecule consists of a long chain of carbon atoms bonded to hydrogen
What is the difference between saturated and unsaturated fatty acids?
•Saturated fatty acids contain single covalent bonds (more hydrogen atoms)
•Unsaturated fatty acids have at least one double covalent bond between carbon atoms ( mess hydrogen atoms)
Structure of glycerol
•3 hydroxyl groups
What bond is formed when a glycerol molecule reacts with molecule of fatty acid?
Ester bond
What is the key feature of triglycerides ?
•Non-polar molecules which means they are hydrophobic and INSOLUBLE in water ( -> makes it useful for waterproofing)
What is the structure of a phospholipid?
• one glycerol molecule bonded to two fatty acid molecules, with the glycerol molecule also being bonded to phosphate
•polar phosphate head is negatively charge (polar)—> the phosphate group is hydrophilic
•non-polar hydrophobic tails
What is the phospholipid bilayer?
The arrangement of phospholipids so that the hydrophilic head groups can interact with the water molecules while the hydrophobic tails cluster together, away from water molecules
What is cholesterol ?
Cholesterol is part of a family of lipids called sterols
What are the key features of a cholesterol molecule ?
•The hydroxyl group is hydrophilic and the rest of the molecule is hydrophobic—> means that cholesterol can insert into cell membranes
What are the roles of cholesterol ?
•The hormones testosterone, oestrogen and vitamin D are all made from cholesterol —> they can pass through the hydrophobic parts of the cell membrane
•used in liver to produce bile
