Polymers, Lipids, Fats, Phospholipids, and Sterols

topic 3

What is a polymer?

Multiple monomers held together by covalent bonds.

What is dehydration synthesis?

The synthesis of a polymer where covalent bonds form between monomers, resulting in the loss of H2O (dehydration).

• NRG + enzymes required (nucleic acids are the exception for NRG)

• how lipids are formed

What is hydrolysis?

The breakdown of polymers by adding H2O (hydration), which breaks covalent bonds between monomers

• Releases NRG

• Requires enzymes

What are lipids?

Fats that provide half the answers to how life evolves

• Creates distinct, separate internal environment

• Eg. Phospholipid Bilayer (example of amphipathic)

What cells are lipids in?

Fats, hydrogenated oils, steroids

Are fats part of cell membranes?

No, they are not part of the membrane (unlike some other lipids).

What is the basic structure of a fat (triglyceride)?

Made up of 1 glycerol molecule and 3 fatty acids, joined by dehydration synthesis.

What factors determine the type of fatty acid?

Length of the hydrocarbon (HC) chain and the number/location of double bonds.

What are saturated fatty acids?

Fatty acids with no double bonds; straight molecules that pack closely together, solid at room temperature (e.g. red meat, butter).

What are unsaturated fatty acids?

Fatty acids with one or more double bonds; bend at double bonds, can't pack closely, liquid at room temperature (e.g. oils, fish, and plants)

• There are two types = Cis and trans

What is a cis fatty acid?

Unsaturated fatty acid where the chains are on the same side of the double bond; naturally occurring, and its fatty acid tail is bent

What is a trans fatty acid?

Unsaturated fatty acid where the chains are on opposite sides of the double bond; unnaturally occurring, its fatty acid tails are straight, and can turn an unsaturated fatty acid tail into a saturated one

What are hydrogenated oils?

Makes the unsaturated fat like a saturated fat by synthetically adding hydrgen to the unsaturated fat and remove its double bonds

Why are oils hydrogenated?

Makes them less perishable, remains more solid at room temp, doesn’t separate compared to animal fat

What are the characteristics of lipids?

• Amphipathic (part hydrophobic/part hydrophilic) but doesn’t have to be

• Lots of non-polar bonds

• Low water solubility

• NOT polymers but STILL macromolecules

What are the function of fats?

NRG source, insulation, and protection

What are the characteristics of fats?

• Almost entirely hydrophobic molecules

• NOT part of the membrane

• made up of 1 glycerol + 3 fatty acids = triacyglycerol

• fatty acids are stuck via attached ester linkage

• formed by dehydration synthesis

Why do variations in fatty acids occur?

It all depends on the length of the HC chain, and its location of the double bond

What are the three types of fatty acids?

1. Saturated

2. Unsaturated

3. Trans

What is the problem with trans fatty acids?

Unnatural, doesn’t digest well, clogs arteries, causes inflammatory response

What is the main function of phospholipids?

A major component of cell membranes due to their amphipathic nature.

What is the structure of a phospholipid?

2 fatty acid tails (hydrophilic head/hydrophobic tail)

• the 3rd carbon of glycerol is attached to the phosphate group

• held by ester bonds

How are the parts of a phospholipid held together?

Ester bonds.

What is the basic structure of sterols?

• A carbon skeleton with four fused rings

• The subtype of steroids

• non-polar

What are the functions of sterols?

Signalling molecules, important part of the membrane due to its amphipathic nature, precursor for steroids

How does variation occur in sterols?

From attachment of different functional groups to the carbon skeleton.

What is an example of a key sterol?

Cholesterol.

What is cholesterol's role?

• Component of animal cell membranes

• precursor to all other steroids

What are the negative health effects associated with cholesterol?

Can clog your artieres

Can there be multiple types of phospholipids?

Yes, it just depends on what’s added to the phosphate group

Can cholesterol be good for you?

Yes, but ONLY if its in the membrane