Top 10 Inventions of The Millennium

• Eraser• Hay• The Stirrup• Reading Glasses• Classical Music• Birth control pills• Transistor

Sodium Polyacrylate Applications

• Absorbs 80x its molecular weight in water

• Used to fight forest fires

• Assists in germinating seeds in arid/dry environments

Why Does Sodium Polyacrylate Work?

• Individual sodium polyacrylate molecules are virtually useless

• Connected into long chains, water molecules are trapped between sodium atoms

Polyethylene

• Arrangement of styrene units into long chains

• Allows strength in longitudinal directions

• Lack of connections between chains makes lateral aspects weak

What Is A Polymer?

Polymers Defined

• Substances made of three or more identical units

• The individual unit is called a monomer; two units are called dimers

• As more monomers are linked, the properties of the substance changes

Gunther VonHagens1993 Hamburg Exhibition of Polymer Art

The Body As Polymer

Four Classes of Biopolymers

• Carbohydrates

• Lipids

• Nucleic Acids

• Proteins

Organic v. Inorganic

• INORGANIC• Lack the element

carbon

• Ex: NaCl, H20, HF

• ORGANIC• Contains the element

carbon

• Ex: CO2, C6H12O6

Why Are All Four Biopolymer Classes Organic?

The Molecular Architecture of Carbon

• High abundance in biosphere

• Tetravalent electron arrangement (4 e- in 2nd valence shell)

• Moderate electronegativity means carbon is unlikely to form ionic bonds

Carbon The Compromiser

• Carbon shares 4 pairs of electrons with other atoms covalently

• This high number of bonds means many other atoms can be linked to carbon

• Covalent bonds useful in biopolymers for resisting entropy

• Silicon is also tetravalent• Silicon (in the form of silica) is frequently

incorporated into living organisms as crystals, spikes or spines

• However, its lower abundance in the lithosphere may explain carbon’s dominance

ISOMERIZATION• Because carbon can form

so many covalent bonds, substances with many carbon atoms can be arranged in many ways

• Isomers are substances with the same number and type of atoms but a different structural arrangement/formula

Polymerization Reactions

Polymerization By Condensation

• A hydrogen atom (H) is removed from one monomer

• A hydroxyl (-OH) group is removed from the other monomer

• Hydrogen and hydroxyl join to form water

• The remaining monomers are covalently linked to form a dimer

Dehydration Synthesis Kinematics

• Energy required to make bonds form

• This is called an ENDERGONIC reaction

• About 200mL of water/day is synthesized in the human body as a result of endergonic reactions

HYDROLYSIS

• Literally means “to split using water”

• The converse of dehydration synthesis

• A water molecule splits into H and OH- groups

• The polymer is divided into monomers

The Kinematics of Hydrolysis

• Since the two monomers have less potential energy than the original polymer, energy is “released”

• This is called an EXERGONIC reaction

• Hydrolysis requires energy to be put in at the start but more energy is freed at the end

If all biopolymers are constructed and destructed in the same way,

what makes them different?

Different Organic Substances Have Different Functional Groups

Carbohydrates

General Characteristics of Carbohydrates

• Literally means ‘water added to carbon”

• Contains ONLY carbon, hydrogen and oxygen atoms in empirical formula

• Ratio of hydrogen to oxygen in empirical formulae is generally 2:1 (i.e. C6H12O6)

• Have caloric value of appx. 4 cal/gram

• May be used for energy flow or structure

Monosaccharides

• Literally translates as “single sugars”

• Monomers/building blocks of carbohydrate polymers

• Three different forms/isomers: glucose, fructose and galactose

Glucose

• Need 9grams/15 minutes of metabolism in bloodstream

• Can only be let into cells via the action of the hormone insulin

• Does not taste sweet

Fructose

• Common natural sugar found in fruits and honey

• Does taste sweet

Glucose v. Fructose

Glucose v. Galactose

Disaccharides

• “Double sugars”• Formed from the

condensation reaction between two monosaccharides

• Water is removed as a result of dehydration synthesis

• Examples: Maltose, Lactose, Sucrose

The bond between monosaccharides is called a GLYCOSIDIC linkage

Sucrose

• Formed from condensation of glucose and fructose

• Table sugar• Does taste sweet

Lactose

• Formed by linking glucose to galactose

• 20% of U.S. population cannot hydrolyze the glycosidic linkage in lactose

• Lactose intolerance

Maltose

• Formed by linking two glucose units together

• Common disaccharide in plants as intermediate storage form of glucose made in photosynthesis

• Does not taste sweet

• Starches consist of hundreds of glucose units connected with an alpha glycosidic linkage

• Cellulose contains equal numbers of glucose units but has a beta glycosidic linkage

• The beta linkage is indigestible in most organisms without the proper enzymes

Characteristics of Proteins

• Contain carbon, hydrogen, oxygen and nitrogen atoms

• Are generally used for structural purposes in living organisms but may also be used for energy flow

• 4 cal/gram if used for metabolism• Highly folded structures held in place with

combination of strong covalent bonds and weak intermolecular forces

There are 20 different Amino Acids: The building blocks of proteins

Amino Acid Form & Function

• Contain CARBOXYL (COOH) and AMINE functional groups

• The 20 A.A. differ in the structure and complexity of their side groups (R-)

• 16 A.A. synthesized in body / 4 must come from diet

• All 20 needed to create the proteins necessary for life

Phenylalanine

Tryptophan

Synthesis of A Dipeptide

• Two A.A. monomers are joined by removing the hydrogen from one amine group and a hydroxide ion from the carboxyl group of another atom

• One water molecule is formed/condensed

• The resulting linkage is a strong bond called a PEPTIDE BOND

Polypeptide Formation

Levels of Peptide Structure

• Primary: Sequence of A.A. held by peptide bonds

• Secondary: Coiled A.A. chain held by disulfide and hydrogen bonds

• Tertiary: Folded coil of A.A. held by hydrogen bonds

• Quaternary: Globular shape held by hydrogen, VanderWaal and other intermolecular forces

Ex: Levels of Structure In Proteins

Preserving this quaternary structure is one of the prime components of

homeostasis

LIPIDS

Characteristics of Lipids

• Comprised of only carbon, hydrogen and oxygen atoms

• Ratio of hydrogen to oxygen is always GREATER than 2:1

• Caloric value of lipids is appx. 9 cal/gram

• Lipids good for long-term storage of energy due to non-polar structure, high caloric value and density

Lipids are comprised of 3 fatty acid monomers linked to a glycerol molecule

Bonding In Fats

• Each fatty acid loses a hydroxyl (OH-) group

• The glycerol backbone loses 3 hydrogen atoms

• Three water molecules are condensed

• The fatty acids and glycerol combine as an ESTER LINKAGE

Saturated v. Unsaturated Fats

• Saturated Fats• All carbon atoms are

bonded to four other atoms via single bonds

• Saturated fats tend to be solid and dense

• Often derived from animals

• Atherosclerosis and obesity may result from overconsumption

• Unsaturated Fats• Some carbon atoms

share more than one pair of electrons

• This is called a double bond or unsaturation

• Unsaturated fats tend to be liquids/oils and often come from plants or aquatic animals

Saturated, Unsaturated and Polyunsaturated Fats

Excess saturated fat is stored in large cells called Adipocytes

Fatty acids may also combine with charged phosphate groups to create phospholipids, which

simultaneously attract and repel water

If heated, the glycerol in fats is changed into a carcinogen called acrolein which causes

digestive distress/heartburn