RECALL:What’s so special about water?

It’s a great solvent.

It hold’s tons of heat.

It has high surface tension.

Its less dense as a solid than a liquid.

Water, pH and Biological Molecules… The Chemistry of Life!

For Polar Molecules, Water Is a Wonderful Solvent

Dissolving table salt (sodium chloride)

Water Holds Immense Amounts of Heat

Forecasts for San Diego and Gallup, 1/11/06 – 1/15/06

Water’s high heat capacity has profound effects on climate and ecology.

Water Has High Surface Tension

High surface tension allows long water columns to be drawn from roots to leaves – even in a redwood.

Water Is Lighter as Solid than as a Liquid

This means that ice forms an insulating blanket over water.

pH Matters

pH is a measure of proton (hydrogen ion or H+) concentration .

In biology, keeping H+ levels within a narrow range is critically important.

Low pH = lots of H+s, high pH = few H+s.

Acids and Bases

An acid produces H+ A base absorbs H+

Carbon’s CoolCarbon’s Cool

Because carbon contains 4 electrons in its outer shell, it can pair in many ways with many different atoms in an “attempt” to fill its outer shell.

Carbon is the central atom of life…

Carbon is the Central Atom of Life.

glucose

amino acids

fat

Some Useful Nomenclature

Learn to recognize these chemical groups.

In Biology, Molecular Shape Matters

Its not just chemical formula, it’s the shape of the molecule that lets it do its “job”.

Never forget the axiom – structure dictates function.

Some major types of biological molecules.

Molecules of Life

Start with water, add lots of small carbon-containing molecules and …….

How do you build a cell?

use these four major classes of biological molecules.

Monomers, Polymers and Macromolecules

Many biological molecules are macromolecules – huge assemblies of atoms.

Biological macromolecules are formed by linking together a set of building blocks (monomers) into long chains (a polymer).

Carbohydrates

Carbohydrates are used for energy and to create structures.

The building blocks for carbohydrates are simple sugars.

Three views of glucose, a common simple sugar.

Linking Simple Sugars – the First Step to a Polymer

A complex carbohydrate is a long-chain polymer made of simple sugars.

monosaccharides a disaccharide

Some Familiar and Important Complex Carbohydrates

Note the way complex macromolecule are built by linking simple repeating units.

Carbohydrates are Central Players in

Energy Production and Storage

Complex Carbohydrates Are Often Used to Create Structures

Cellulose is the most abundant macromolecule on earth – and you’re probably wearing it now.

Lipids are Hydrophobic Molecules That Exist In Three Primary Forms

Sterol

FatPhospholipid

Fats Are Made By Linking Fatty Acid Chains to Glycerol, a Three Carbon Molecule

Space-filling model of a fat

A fatty acid

Molecular Structure of a Fat

Fats are Used in Energy Storage and Production

The Degree Of Saturation In A Fat Affects Its Physical And Health Properties

Where are the double bonds?

Cis and Trans Unsaturated Fats

all cis polyunsaturated

“Good”

Omega-3-fatty acids

mono- and poly-unsaturated

saturated

trans

“Bad”

Sterols

Note the four ring structure common to all sterols.

Sterols are: 1) essential membrane components and 2) form many hormones.

Sterols As Hormones

“Designer steroids” are major sporting news where they have been used illegally in track and field, baseball, football and countless other sports.

A heavily muscled Linford Christie who was disqualified from international competition after testing positive for a banned steroid.

Phospholipids are Building Blocks of Cellular Membranes

The hydrophilic head group and hydrophobic tails are the keys to phospholipid function.

Phospholipids have a molecular Jekyll and Hyde split personality.

Hydrophilic Head Group And Hydrophobic Tails Are The Keys To Phospholipid Function

Phospholipids Form Double-Layered Biological Membranes

Protein

Proteins are THE key elements of life.

Remember the principle - structure determines function.

Since proteins are the key players of the cell, it follows that protein structure determines cell function.

Some of the Diverse Functions of Proteins

Proteins are Linear Chains of Linked Amino Acids

A Common Thread and a Unique Identity

Amino Acids, Peptide Bonds, Polypeptides, Protein

Peptide bonds

Proteins are linear chains of 20 different building blocks called amino acids.

Amino acids are linked by peptide bonds – a form of covalent bond.

Proteins are Folded Structures Whose Shape (and therefore function) Depends on Amino Acid Sequence

Primary Structure•Conformation:

Linear structure

•Molecular Biology: each type of protein has a unique primary structure of amino acids

•Ex: lysozyme

•Amino acid substitution: hemoglobin; sickle-cell anemia

Secondary Secondary StructureStructure•Conformation: coils & folds (hydrogen bonds)

•Alpha Helix:coiling; keratin

•Pleated Sheet: parallel; silk

Tertiary StructureTertiary Structure•Conformation: irregular contortions from R group bonding√hydrophobic√disulfide bridges√hydrogen bonds √ionic bonds

Quaternary Quaternary StructureStructure•Conformation: 2 or more polypeptide chains aggregated into 1 macromolecule√collagen (connective tissue)

•√hemoglobin

Nucleic Acids

There are two kinds of nucleic acids, DNA and RNA. Both are involved in the storage and flow of information from gene to gene product.

DNA

Recently, we’ve learned that RNA also plays important regulatory roles.

Nucleotides Are the Monomers That Create Polymers of DNA and RNA

Nucleotides fuel the cell and coordinate its metabolism.

Nucleotides are Important in Their Own Right

ATP, the cell’s primary energy currency.