PH BIO SCI 21 - 3. Lipids

Lipids

This is known as a provide a major way of storing chemical energy and carbon atoms in the body.

Fats

surround and insulate vital body organs, providing protection from mechanical shock and preventing excessive loss of heat energy

Functions of fats include:

surround and insulate vital body organs
providing protection from mechanical shock
preventing excessive loss of heat energy

Phospholipids, glycolipids, and cholesterol

Basic components of a cell membrane

Cholesterol

Several ________ derivatives function as chemical messengers (hormones) within the body

Hormones

chemical messengers

Lipids are:

organic compounds found in living organisms

insoluble (or sparingly soluble) in water

soluble in nonpolar organic solvents

do not have

Lipids __________ a common structural feature that serves as the basis for defining such compounds.

solubility

Lipids are characterized based on ____________.

insoluble

All lipids are _________ in water.

Methods of subclassifying lipids

1. Biochemical function
2. Based upon whether or not saponification occurs in hydrolysis

5 Categories of Lipids

Energy-storage lipids
Membrane lipids
Emulsification lipids
Messenger lipids
Protective-coating lipids

Energy storage lipids

triacylglycerols

Membrane lipids

Phospholipids
Sphingoglycolipids
Cholesterol

Emulsification lipids

Bile acids

Messenger Lipids

Eicosanoids
Steroid Hormones

Protective-coating lipids

BIological waxes

Saponifiable lipids

Triacylglycerols
Phospholipids
Sphingoglycolipids
Biological waxes

Non Saponifiable Lipids

Cholesterol
Steroid Hormones
Bile Acids
Eicosanoids

Saponification

a hydrolysis reaction that occurs in basic solution

Saponifiable lipids

converted into smaller molecules when hydrolysis occurs

Nonsaponifiable lipds

cannot be broken up into smaller units since they do not react with water

Saponification classification system is widely used for

Lipid classification

Fatty acid

building block of lipids

energy-storage lipids (Triacylglycerols)

most abundant type of lipid

membrane lipids

second most abundant type of lipid

monocarboxylic acid

A fatty acid is a naturally occuring ______________, and always contain an even number of carbon atoms and have a carbon chain that is unbranched.

Characteristics of Fatty Acids

1. Unbranched carbon chain
2. Even number of carbon atoms in the carbon chain
3. Double bonds, when present, in a cis configuration

Short chain fatty acids

C4 and C6

Medium chain fatty acids

C8 and C10

Long-chain fatty acids

C12 to C26

no

Saturated fatty acids (SFAs) contain ______ double bond/s.

single bonds

A saturated fatty acid is a fatty acid with a carbon chain in which all carbon–carbon bonds are ________.

Common name of Hexadecanoic acid

Palmitic Acid

one

Monounsaturated fatty acids (MUFAs) contain ______ double bond/s.

cis

In biochemically important MUFAs, the configuration about the double bond is nearly always ______, putting a rigid 30° bend in the chain, affecting the physical properties of a fatty acid.

two or more

Polyunsaturated fatty acids (PUFAs) contain ______ double bonds

Omega-3 fatty acid

An ___________ is an unsaturated fatty acid with its endmost double bond three carbon atoms away from its methyl end.

Omega-6 fatty acid

An _________________ is an unsaturated fatty acid with its endmost double bond six carbon atoms away from its methyl end.

The SFA 12:0 is known as

Lauric acid

The SFA 14:0 is also known as

Myristic acid

The SFA 16:0 is also known as

Palmitic acid

The SFA 18:0 is also known as

Stearic acid

The SFA 20:0 is also known as

Arachidic acid

The MUFA 16:1 ∆9 is known as

Palmitoleic acid

The MUFA 18:1 ∆9 is known as

Oleic acid

The PUFA 18:2 is also known as

Linoleic acid

The PUFA 18:3 is also known as

Linolenic acid

The PUFA 20:4 is also known as

Arachidonic acid

The PUFA 20:5 is also known as

EPA (Eicosapentaenoic acid)

The PUFA 22:6 is also known as

DHA (Docosahexaenoic acid)

MUFA

What is the type designation of this fatty acid? (SFA, MUFA, or PUFA)

12:1 Fatty Acid

On the basis of carbon chain length and degree of unsaturation, what is the numerical shorthand designation for this fatty acid?

Omega-3 fatty acid

To which “omega” family of fatty acids does this fatty acid belong?

Delta-9 Fatty Acid

What is the “delta” designation for the carbon chain double-bond location for this fatty acid?

Which best describes the relationship of water solubility and carbon chain length?

Solubility decreases; carbon chain length increases

slight solubility

short-chain fatty acids have a _____________ in water.

insoluble

long-chain fatty acids are essentially __________ in water.

carboxyl group

The slight solubility of short-chain fatty acids is related to the polarity of the ____________ present.

Which best describes the relationship of melting point and carbon chain length?

As carbon chain length increases; melting point increases

The greater degree of unsaturation; the smaller the melting point

Which best describes the relationship of melting point and degree of unsaturation?

saturated

Long-chain ____________ fatty acids tend to be solids at room temperature

unsaturated

Long chain ____________ fatty acids tend to be liquids at room temperature.

bends

The ________ prevent unsaturated fatty acids from packing together as tightly as saturated fatty acids.