Organic Molecules

• Contain C

– Can form 4 strong covalent bonds

– Ergo can form many complex, stable molecules

– Chemistry of life is complex, and requires complex

molecules

– However, several kinds of molecules contain carbon

but are not organic. CO2, for example

– All organics are naturally produced by processes in

living cells.

The greater % of any organism consists of 4 elements:

carbon, oxygen, hydrogen and nitrogen.

The Four Main Types of

Organic Molecules • Carbohydrates

– Structure

• Consist of C, H, O

• General formula = (CH20)n

• Often end in -ose

sugars

• 1.) Monosaccharides- simple sugars one ring; most are

C6H12O6

– Isomers: same number and type of atoms, different structure

» Glucose- store and release energy, mainly from C-H bonds;

main transport sugar in vertebrates

» Fructose

» Galactose

The straight chains form rings in

solution.

Monosaccharide isomers

• The difference between glucose and galactose is

simply in the way two things (H and OH) are

attached to one of the carbons in the ring.

Double sugars

• 2.)Disaccharides :eg – sucrose, lactose, maltose

– 2 mono’s bonded by dehydration synthesis

– Hydrolysis breaks them back into mono’s

– Sucrose = glucose bonded to fructose

» It is the main transport sugar in plants

Complex Carbohydrates

• Complex Carbs

– Polysaccharides-most are glucose polymers which form chains and branches

• Animal starch - glycogen

– Store energy in liver and muscles

• Plant starch- amylose

• Cellulose- structural function

– Cell walls

• Chitin-arthropod exoskeleton, fungus cell walls

Making and Breaking Organics

• All large organic polymers are made by joining smaller molecules called monomers in a chemical process called dehydration synthesis.

• They are broken back down by hydrolysis.

Lipids • Lipids-functions include energy storage, forming structural

parts, insulation, cushioning body organs, and being hormones

– Store 2 X as much energy/gram as carbs

– Insoluble in H2O

Structure of most common lipids: Glycerol and fatty acids- Triglyceride (main type of lipid): 3 fatty acids and gycerol

• Fats and oils-

– Fats:Saturated- no double bonds between carbons, most H possible, animal products, solid at room temp.

– Oils: Unsaturated- double bonds, liquid (oils), plant products

– Lipid with a structural function example: Phospholipids in ALL cell membranes (NOT cell walls)

– Omega 3 oils are unsaturated and very healthy

– Hydrogenated trans fatty acids are bad

• Waxes

• Lipids are an exception among macromolecules

because they do not have polymers.

• The unifying feature of lipids is that they all

have little or no affinity for water.

– This is because their structures are dominated by

nonpolar covalent bonds.

• Lipids are highly diverse in form and function.

Introduction

Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

• Although fats are not strictly polymers, they are

large molecules assembled from smaller

molecules by dehydration reactions.

• A fat is constructed from two kinds of smaller

molecules, glycerol and fatty acids. You should

be able to recognize a sketch of a fatty acid and a

glycerol.

1. Fats store large amounts of energy

Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

• Glycerol consists of a three carbon skeleton with

a hydroxyl group attached to each.

• A fatty acid consists of a carboxyl group attached

to a long carbon skeleton, often 16 to 18 carbons

long.

Fig. 5.10a

• The many nonpolar C-H bonds in the long

hydrocarbon skeleton make fats hydrophobic.

• In a fat, three fatty acids are joined to glycerol

creating a triglyceride.

Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

Fig. 5.10b

Saturated vs. Unsaturated Fats

Lipid hormones made from

cholesterol

Cholesterol is a sterol. Not a

glyceride type, but a lipid still.

Cholesterol is needed for:

• Your cells use it to make the sterol

hormones testosterone and estrogen as well

as vitamin D (with sunshine’s help in your

skin cells).

• Cholesterol is in all animal cell membranes,

but not plant or any other cell membranes,

which is why plants have no

cholesterol.Watch

Proteins - Amino Acid Polymers

Peptide bond formation

• Amino acids are joined by a type of covalent bond called a peptide bond during dehydration synthesis. Bonding is always between the carboxyl group of one and the amine group of the other.

Proteins show great variety

• There are 20 different kinds of amino acids

• An infinite number of different proteins is

possible by combining different amino acids

in different sequences.

• In actuality, we find several thousand kinds

of proteins in living things.

Protein Functions

• Structural proteins- eg. Keratin, collagen, silk

• Hormones: Insulin, Human Growth Hormone

• Enzymes- catalysts; ususally have an -ase ending. Sucrase.

• Transport proteins: in cell membrane and in circulatory systems. Hemoglobin, for example.

• Defense function: Antibodies - made by white blood cells in the immune system

Denaturation - when bonds break, often by heat, the protein loses its natural shape, and therefore its function

Primary Structure

• The order of amino

acids determines what

the shape of every

protein will ultimately

be.

• Identical chains will

always fold up the

same way.

Even small changes in primary

structure can be deadly

Secondary structure

• Linus Pauling won a

Nobel Prize for

discovering the alpha

helical shape of many

proteins. 20 structure is

caused by hydrogen

bonding between amino

acids in the chain,

producing regular,

repeated patterns.

Tertiary Structure

• These irregular

foldings are due to

many different types

of bonds between R

groups. The H bonds

which determine

secondary structure

are not between R

groups.

Quaternary structure: multiple

chains combine to make 1 protein

Two overall shapes of proteins

• When a protein has taken its final shape, it

will be classified as one of two possible:

• Fibrous (string-like): Collagen, silk

• Globular (roundish): Hemoglobin, insulin,

all enzymes

• Let’s look at some animations…

• Secondary tertiary quaternary

Which of the following is not

normally a function of proteins in

healthy cells?

A. functioning as catalysts

B. long-term energy storage

C. a component of cell membranes

D. Transport of particles

Athletes are often concerned with the question of

how much protein they need in their diets

because of the requirement of growing muscles

for protein. Just as muscles need the basic

building block of protein, protein itself has basic

building blocks. Which of the following are

the basic building blocks of protein?

a. Nitrates

b. Amino acids

c. Monosaccharides

d. Nucleotides

Based on the students’ results, at what pH does

catalase work best: 1,4,7, or 10?