Lipids

hydrophobic properties of lipids

hydrophobic properties of lipids

Less soluble in water, but ighly soluble in non polar substances like ethanol, propanol and more. Lipids are not repelled by water they are just more attracted towards non polar substances.

triglycerides by condensation

3 fatty acids+ 1 glycerol through condensation produce 3 water molecules.

bond between fatty acids and glycerol is an ester bon, which s formed when acid reacts with hydroxyl group in an alcohol.

one carboxyl group on fatty acids and hydroxyl group on glycerol

completely hydrophobic as the groups which are hydrophilic get used in condensation.

Phospholipids

two fatty acids+ glycerol + phosphate group

phosphate group is hydrophilic causing phospholipids to be partially hydrophobic and partially hydrophilic

amphitpathic

partially hydrophobic and partially hydrophilic

fatty acids

hydrocarbon chain

acid part is carboxyl gorup on one end and on the other end there is methyl gorup

no. of carbon atoms varies

bonding also varies some are single bond which bond with two hydrogen atoms other are double bonds which bond with adjacent carbon in the chain and bond to one hydrogen

three types: monosaturated, unsaturated, and polysaturated.

Saturated fatty acids

In this all bonds between carbon atoms is single causing maximum number of hydrogen possible

Unsaturated fatty acids

one or more double bonds thus reducing no. of hydrogen and one double bond is called monounsaturated, and more than one is called polysaturated

Cis fatty acids

hydrogen atoms on same side as double bond, triglycerides with cis fatty acis are less good at packing together thus they have low melting point

whereas with cis unsaturated fats they are liquid at room temperature

Trans fatty acids

alternative arrangement for hydrogen on opposite sides

straight chain, high melting point and solid at room temperature.

hydrogenation of vegetables

solid fats are produceed in processed food

ban use of industrial trans fats

bad for the body

Adipose tissues for energy storage and thermal insulation

triglycerides are useed for energy store for animals and plants

adipose tissues are the tissues right under skin throughout body also called body fat.

fats in animals are stored in this area and in human it is right under the skin and beneath the kidney

reason why triglycerides are good for energy storage is that they are chmeically stable thus energy is not lost

they form droplets in the cytoplasm thus not having osmotic effect on the cell.

release twice as much energy in cell respiration as carbs thus enough energy can be stored in half body mass

theu are poor conductors of heat, used as thermal insulatores in animals to convserve heat

liquid at body temp act as shock absorber.

animals living in cold regions have thick adipose tissues, and in marine animals this is called blubber

Since in marine animals like sea lions they have problems with overheating as they reach the ground to breed, it is because of blubbler produced by metabolism and air is much warmer than water.

Phospholipid Bilayers

phospholipids are amphipathetic, leads to phosphate group is hydrophilic and the two hydrocarbons are hydrophobic.

there is a phosphate head, and hydrocarbon tail in a simplfied diagram of the phospholipid molecule

Phosphate heads are attracted to water when they mixed and hydrocarbons are attracted to each and repelled by water, thus they are arranged in double layer with the tails facing each other thus they are inwards and the heads are facing outwards towards the water. this is the basis of the cell membrane

Steroids through phospholipid bilayer

the bilayer is permeable to non polar substances

steroids are group of lipids with molecules like sterols, there cyclohexane rings, and one cyclopentane ring, there are 17 carbon atoms in total .

they are hydrophobic and can easily and exit through the cell and the bilayer.

it is easy for non polar substances to pass through fatty acid of cell memebrane

oestradiol is an anabolic steroid

tesosterone is chemically very simlar to oestradiol and is made from sterioid cholesterol, made in liver and absorbed in diet.

• muscle growth is casused due to secretion frm testosterone