Functions:

1. Rich energy source (2x carbohydrates)

2. Provides insulation

3. Provides protection against injury

4. Facillitates transport of Body fluids

5. Specific roles as vitamins and hormones

I. Structure and Features

A. Special properties* insoluble in water

* soluble in organic solvents

( butane, acetone, hexanes…)

* All contain

Carbon (C)

Hydrogen (H)

Oxygen (O)

(Phosphate is common)

Examples:

*fats

*waxes

*oils

B. Functional Groups

Carboxyl C=O OH

Methyl H C H H

C. Triglycerides

Lipids made of three fatty

acids and one glycerol

D. Formula for Fatty acids

CH3(CH2)nCOOHMethyl carboxyl

Long carbon chain

( “n” can be 3- hundreds)

Example: Stearic acid(Beef Tallow)

CH3(CH2)16COOH

E. Dehydration Synthesis/ Condensation Reactions

One glycerol and three fatty acids bind together where the glycerol loses 3 “H” molecules and each fatty acid loses an “OH”. Three water molecules and one triglyceride is formed.

  glycerol        +        3 fatty acids         =         a fat or oil

                  +                                          =         

                               

R= long carbon chain

 

F. Van der Walls Forces

Harmonic oscillations between C-H bonds, where electrons travel backand forth creating a great force. The more carbon in the chain, the higher the forces.

http://antoine.frostburg.edu/chem/senese/101/liquids/faq/h-bonding-vs-london-forces.shtml

G. Lipids are Amphipathic

A Hydrophilic (water-loving )polar

carboxyl end

A Hydrophobic (fear of water)

nonpolar methyl end

II. Types of Lipids

Fatty acids can be classified as saturated or unsaturated.

 

 Saturated            Unsaturated All C filled with Not filled with hydrogen hydrogen

contain all C-C        contain at least single bonds             one C=C double

High VDW forces Lower VDW forces

Longer chains Shorter chains usually solid at           usually liquid at room room temperature      temperature (higher melting           (lower melting points) points)                        most often found        most often found in animals (fat)           in plants (oils)

A B

The straighter, saturated Fatty Acids all line-up veryclose together and stick to each other. These interactions make them less fluid and more solid (more like Fat).

The double bond gives unsaturated fatty acids a bend in the chain. This bend affects the chemical characteristics of unsaturated fatty acids. The bent unsaturated Fatty Acids can't get as close together, so they don't stick as much. They are more fluid (more like Oil).

Saturated Unsaturated

(saturated)

(saturated)

(unsaturated)

Examples in nature:

Summer /warm * become more saturated

* increase temp. cause double bonds to break, membranes become more solid, chains longer, higher melting point, harder to break

* 10W40 longer chains, saturated

* tropical plants, higher energy, worse for you. Ex. Palm oil, coconut oil

Goldfish pond

Car oil

Foods

Winter/ Cold

* become unsaturated * decrease temp. cause more double

bonds to form, membranes become more liquid, chains shorten, lower melting point, easier to break

* 10W30 shorter chains, unsaturated

* temperate climate plants, lower energy, healthier for you. Ex. Olive, corn, peanut oil

Goldfish pond

Car oil

Foods

Phospholipids are important structural components of cell membranes. Phospholipids are modified so that a phosphate group (PO4

-) is added to one

of the two fatty acid chains.

C.

D. Waxes

Waxes are an important structural component for many organisms, such as the cuticle, a waxy layer covering the leaves and stems of many land plants; and protective coverings on skin and fur of animals.

E. Steroids•All have a similar 4 ring structure•Side groups very

F. Soaps

• Salts of fatty acids

• Emulsifies not dissolves oil/lipids

Interesting fact

Olestra (also called Olean) is formed by chemical combination of sucrose molecules are much larger than those of ordinary fats, the body's digestive enzymes cannot break them down.

*not absorbed into the body.

*similar to insoluable fiber

*Olean passes through the

digestive tract without

Added dietary fat /calories.

Lap top review• http://www.hhmi.org/biointeractive/obesity/molfat/index.html

( interactive overview of lipids)

• http://science.nhmccd.edu/biol/dehydrat/dehydrat.html (dehydration reactions)

• http://www.okstate.edu/hes/nsci/nutrition/NSCI2114/digestion.htm (select “Carbohydrate” and “Lipid Digestion” to see video reviews)

• www.teacherweb.com/MD/mounthebron/donoghue link to eScigs..click on eGuide 2.0 Student Resources, go to link

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