1.1 Lipids

what is the solubility of lipids

1. Contain hydrocarbon molecules(non polar bonds)

2. Insoluble in polar substances

3. Lipid solubility improved by combo with other molecules(eg: glycolipids, lipoproteins)

What is a triglyceride

3 fatty acids attached to one glycerol molecule

Saturated-single bonds

What is the process of forming triglycerides

Esterification(condensation reaction that forms 3 h2os

Formation of phospholipids

2 fatty acids only bonded to a glycerol molecule, 3rd one replaced by a phosphate ion(PO43-)

Solubility of phospholipids

Amphipathic(hydrophilic phosphate head, hydrophobic fatty acid tail)

Which contain more energy, lipids or carbohydrates?

Lipids due to their higher number of C-H bonds

Properties of triglycerides

1. Hydrolysis releases glycerol and fatty acids(which form useful respiratory substrates)

2. Energy storage: Lipids Insoluble→aren’t transport easily→remain in storage cells

3. Lots of h2o produced when lipids r respired compared to carbs(metabolic water can be used when h2o unavailable)

4. Insulation and protection: triglycerides stored in adipose tissue→thermal insulation and cushions organs(in animals)

Adipose tissue to store lipid(for insulation and protection)

Subcutaneous fats stored below skin

Visceral fats stored around major internal organs

Endothermic(seals and walruses)→have thick adipose tissue called blubber→helps trap heat generation by respiration

Properties of phospholipids

1. Membrane structure: phospholipid bilayers form cell membranes→controls movement on substances in n out of cell

2. Membrane fluidity: level of saturation in fatty acid tails influence membrane fluidity(for cellular function)

Saturated fatty acids properties

1. Straight molecules(molecules packed tightly tg)→increase melting point

2. Storage for animals as it’s solid at rtp

Unsaturated fatty acids properties

1. Doubles bonds cause kink→they cannot pack as tightly as saturated→liquid at rtp

Difference between mono and polyunsaturated fatty acids

Mono(single double bond): lower mp than saturated fatty acids

Poly(many double bonds): low mp(forms oils for storage in plants)

How do non-polar steroids pass through the phospholipid bilayer?

Steroid hormones contain cholesterol→hydrocarbon region of cholesterol is non-polar

What are examples of steroid hormones

Oestradiol

Testosterone

Difference between trans fat and cis fat(unsaturated)

Cis has both hydrogens on the same side→increases good cholesterol(healthy)

Trans has one hydrogen on top of one carbon and below the other carbon→increases bad cholesterol(unhealthy)

Structure of steroid

fused 4 ring structure

What are essential features of the structure of a fatty acid

1. Carboxyl group(COOH)

2. 2 H on each C except the last C has 3 H(CH3)