lipids 1

what are lipids?

fatty compound soluble in nonpolar organic solvents and insoluble in polar solvents / water

examples of organic solvents lipids are soluble in

1. benzene

2. chloroform

3. ether

4. hot alcohol

5. acetone

what do lipids describe?

chemically varied group of fatty substances and are highly concentrated storage of energy

what do lipids serve as?

• fuel molecules

• signal molecules

what are lipids a component of?

1. membranes

2. hormones

3. intracellular material

what are lipids? what are they long chains of?

they are esters of long chain in fatty acids and alcohol

what are the functions of lipids?

1. components of cell membranes

2. regulate membrane permeability

3. protect internal organs

4. serve as insulating materials

5. gives shape and smoothness to the body

6. serves as a source of fat, soluble vitamins

7. essential fatty acids are useful for transport of cholesterol and formation of lipoproteins

8. phospholipids in mitochondria are responsible for transport of electron transport chain components

what prevents accumulation of fat in the liver?

phospholipids

what do phospholipids help in the removal of?

they help in the removal of cholesterol from the body by participating in reverse cholesterol transportation

what is cholesterol a constituent of? what does it synthesize?

• it is a constituent of membrane structure

• it synthesizes:

  • bile acids

  • hormones

  • vitamin D

what is cholesterol considered?

It is considered the principal sterol of higher animals, abundant in nerve tissues and gallstones

what are a storage form of energy?

triglycerides

what are structural components of the biomembrane?

phospholipids and cholesterol

what are the metabolic regulators?

• steroid hormones

• prostaglandins

what act as surfactants, detergents, and emulsifying agents?

amphipathic lipids

lipids act as what type of insulators in neurons?

electrical insulators

what provides insulation against changes in external temperature?

subcutaneous fat

what do lipids do the body?

give it shape and contour

what protects the internal organs by giving it a cushioning effect?

pads of fat

what do lipids aid in the absorption of? what do they improve?

• aid in the absorption of fat soluble vitamins (A, D, E and K)

• improves taste and palatability to food

what form can lipids be found in?

• liquids

• non-crystalline solids at room temperature

pure & fat oils are what?

• colorless

• odorless

• tasteless

lipids are what? what are they soluble and insoluble in?

• energy-rich molecules

• they are soluble in organic solvents

  • alcohol

  • chloroform

  • acetone

  • benzene

• insoluble in water

do any ionic charges occur in lipids?

no. there is no ionic charges

what are solid triglycerols?

• fats

• higher proportion of saturated fatty acids

what are liquid triglycerols?

• oils

• higher proportion of unsaturated fatty acids

what is the structure of lipids? what does it depend on? what are they characterized by?

• varies depending on type

• in general, lipids are characterized by their hydrophobic nature

what are lipids primarily composed of?

• carbon (C)

• hydrogen (H)

• oxygen (O)

sometimes, they contain:

• phosphorus (P)

• Nitrogen (N)

• or other elements

lipids are made up of what elements? what do they have a lower proportion of?

• they are made up of elements carbon, hydrogen and oxygen

• they have a lower proportion of water than other molecules, such as carbohydrates

unlike polysaccharides and proteins, lipids are not what?

• polymers. they lack a repeating monomer unit

what two molecules make up lipids?

1. fatty acids

2. glycerol

what is the structure of triglycerides?

• they are composed of one glycerol molecule and three fatty acids

• glycerol molecule is a three-carbon alcohol, and each carbon is attached to a hydroxyl group (-OH)

• fatty acids are long hydrocarbon chains with a carboxyl group (-COOH) at one end

glycerol structure in triglyceride

• C3H8O3

• 3 hydroxyl groups attached to 3 carbon atoms

fatty acid structure in triglyceride

long chains of hydrocarbons (CH3 - (CH2)n-COOH), where n can range anywhere from 2 to 28 carbon atoms

formation of triglycerides

• they are formed through esterification, where the carboxyl group of each fatty acid reacts with one of the hydroxyl groups of glycerol, which then releases 3 water molecules, forming ester bonds

  • glycerol ex: HOCH2 - CH(OH)-CH2OH

  • fatty acid ex: CH3 - (CH2)14 - COOH (palmitic acid)

structure of phospholipids

• similar to triglycerides, but differ in having 2 fatty acids attached to glycerol molecule, with 2nd hydroxyl group of glycerol attached to a phosphate group

  • this can be modified by other molecules like:

    • choline

    • ethanolamine

    • serine

glycerol group in phospholipids

same as triglycerides

• 3 hydroxyl groups attached to 3 carbon atoms

fatty acids in phospholipids

two long hydrocarbon chains attached to the glycerol backbone

where is the phosphate group attached in phospholipids

the third carbon of glycerol

what is the hydrophilic head of phospholipids

the phosphate group, often linked to another molecule like choline, is water loving

what are the hydrophobic tails of phospholipids

fatty acid chains are water-hating

what is the function of phospholipids?

• crucial in forming cell membranes, where they arrange themselves in a bilayer:

  • hydrophilic heads face the water on the inside and outside of the cells

  • hydrophobic tails face inward, away from the water