Lecture 3: Lipids

What are fatty acids?

They are long chain carboxylic acids, which work as a building blocks for triglycerides, phospholipids, and sphingolipids.

What is triglyceride?

It’s a molecule that has glycerol center and three fatty acids as side chains (used as major energy storage molecules.)

What is phospholipid?

It’s a triglyceride molecule that has a charged phosphate head group (molecule is amphiphilic).

What does it tell if molecule is amphiphile?

That it has hydrophilic and hydrophobic parts

What is the job of Surfactant?

They reduce the surface tension, which helps the removal of dirt and oils

Why fatty acids have even amount of carbons in their chains?

Due to biosynthesis based on oligomerization of acetate

How is Malonyl-CoA formed?

From acetyl-CoA and CO2 in the biosynthesis of fatty acids

What is Sphingolipid?

It’s a lipid that has one hydrophobic group replaced by sphingosine (molecules are part of the cell membrane)

In where is cholesterol crucial component?

In cell walls, bile acids, and steroid hormones.

Where do lipophilic compounds occur?

in living organisims

What kind of number carbons natural long-chain carboxylic acids typically have?

Even

What is carboxylic acid chain called when it has no double bonds?

Saturated fatty acid

What happens to the melting point of fatty acid molecule, when the amount of carbons on the chain increases?

It increases

What is fatty acid called, when it has one double bond on the chain?

Unsaturated fatty acid

What is fatty acid called when it has two or more double bonds on the chain?

Polyunsaturated fatty acid

How does double bonds affect fatty acids structure and melting point?

They bend the structure and decrease the melting point

what kind of olefins natural unsaturated fatty acid have?

cis-olefins

What are Waxes?

They are molecules made of esters of fatty acids and a long-chain alcohols, which are highly lipophilic.

What kind of biological role triglycerides have?

They are major energy storage of molecules and work as building blocks for amphiphiles

How are unsaturated fatty acids named by their form in room temperature?

If they are in solid form, then they are called fats, but if they are in liquid form, then they are oils

Why does fatty acids have different melting points?

because they have different amount of carbons on the chain and some chains have cis-olefin causing a bend in the lipophilic tail, which prevents molecules packing densely leading to less attractive intermolecular interactions

What is trans-fat?

It is fatty acid, which has trans-olefin

How does industrial trans-fats differ from natural ones?

The industrial ones are made by hydrogenation of fatty acid with nickel as catalyst

How to create soap from fatty acid?

By going through basic hydrolysis

Are soaps amplifies?

yes

What does soap molecule consist of?

A head group with high affinity to polar species and lilophilic tail which is highly hydrophobic

How to create firm soaps?

By using NaOH in hydrolysis.

How to create soft/liquid soaps?

By using KOH in hydrolysis.

What is phospholipid?

It’s triglyceride with phosphate as a head group

What are phospholipids key building blocks of?

lipid bilayer membranse

Why soap molecules form micelles?

Because micelles trap dirt and grease, thus helping removing them

What kind of structure do phospholipids form to be used in cell wall membranes?

Extended sheets

What is terpenes?

It’s a chain of isoprene units

What part does terpenes play in archaea

Archaea cell wall membranes contain terpenes, which works like a backbone

What do other lipids bring to extended phospholipid sheets?

They bring stability, permeability and fluidity

What kind of head group sphongolipids usually have?

Ethanolammonium, phosphate or carbohydrate ones

What part does cholesterol play?

its crucial building block of cell walls, bile acids and core structure of steroidal hormones

What part does cholesterol play in bloodstream?

They transfer lipoproteins

What Sphingolipids do?

They work as cell membranes modifiers

Where is lipophilic compounds soluble?

In non-polar solvents