CHAPTER 3

BIOCHEMISTRY

ORGANIC COMPOUNDS

• COMPOUNDS SYNTHESIZED BY CELLS AND CONTAIN CARBON

FUNCTIONAL GROUPS

• ATTACHED TO CARBON SKELETON –

• AREA THAT PARTICIPATES IN CHEMICAL REACTIONS

FUNCTIONAL GROUPSGROUP SYMBOL NAME OF COMPOUND FUNCTION

Hydroxyl -OH Alcohols; carbohydrates

Aldehydes

(when =O end of chain)

Polar;

hydrophilic

Carbonyl -CO Ketones

(when =O occurs in the middle of chain

Polar;

hydrophilic

Carboxyl -COOH Carboxylic Acids;

Fatty acids

Act as acids

Amino -NH2 Amines

Carbon’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.

MOLECULES OF LIFE

• CARBOHYDRATES

• LIPIDS

• PROTEINS

• NUCLEIC ACIDS

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).

POLYMERS( LARGE MACROMOLECULES OF 3 TO

MILLIONS OF MONOMERS)

• 4 CLASSES

• POLYSACCARIDES

• TRIGLYCERIDES

• POLYPEPTIDES ( PROTEINS)

• NUCLEIC ACIDS

MONOMERS(SUBUNITS OF POLYMERS)

• MONOSACCARIDES

• GLYCEROL AND FATTY ACIDS

• AMINO ACIDS

• NUCLEOTIDES

FORMATION OF POLYMERS

When 2 monomers join a hydroxyl –OH group is removed from one monomer and a –H is removed from other ; water is given off

CONDENSATION REACTION- water is removed and a bond made

con

CONDENSATION REACTION

BREAKDOWN OF POLYMERS

• HYDROLYSIS REACTION--

• REVERSE OF CONDENSATION RX

• -OH group from water attaches to one monomer and –H attaches to the other

CarbohydratesCarbohydrates are used for energy and to create structures.

The building blocks for carbohydrates are simple sugars. ( glucose, fructose

Three views of glucose, a common simple sugar.

MONOSACCARIDES

• 1) 6 CARBON SUGARS

• GLUCOSE AND FRUCTOSE (C6H12O6)

• Isomers- same formula different arrangement of atoms

• **draw glucose and fructose in notebook using text

• 2) Ribose and deoxyribose –

• 5 carbon sugars important in DNA /RNA

• **draw in notebook

DISACCARIDES

• CONTAIN 2 MONOSACCARIDES

• LACTOSE= GALACTOSE + GLUCOSE

• ( FOUND IN MILK)

• MALTOSE= GLUCOSE + GLUCOSE

• ( DIGESTION OF STARCH)

Linking Simple Sugars – the First Step to a Polymer

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

monosaccharides a disaccharide

POLYSACCARIDES

• CHAINS OF GLUCOSE MOLECULES

• 4 OF THEM:

• STARCH

• GLYCOGEN

• CELLULOSE

• CHITIN

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

• Types:• Fats, Oils, waxes, phospholipids, steroids

• Hydrophobic• Composed of monomers called fatty

acids•

Fatty acid

Lipids are Hydrophobic Molecules That Exist In Three Primary Forms

Steroid

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”

At a Store Near You

Beginning January 1, 2006, the FDA required that the amount of trans fat be listed on all food labels.

The new line showing levels of trans fat

Sterols

Note the four ring structure common to all sterols.

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

Sterols As Hormones

Estrogen, testosterone, progesterone, and corticosteriods (cortisol) are all steroid 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. Forget DNA, proteins rule.

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

Strands of the Protein Keratin Create Hair

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

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.