The Chemical Building Blocks of Life

Outline: The Chemical Building Blocks of Life

1. Chemistry of Carbon

2. Polymers & Monomers

3. Biologically Important Compounds Carbohydrates Lipids Proteins Nucleic Acids

3

Biological MoleculesBiological molecules consist primarily of

-carbon bonded to carbon, or-carbon bonded to other molecules.

Carbon can form up to 4 covalent bonds.

Carbon may be bonded to functional groups with specific properties.

ProtonsNeutronsElectrons

1. Carbon has 4 valence electrons

2. Each carbon atom four covalent bonds

Carbon Chemistry

Electron PairCovalent Bond

Covalent Bonds in Carbon

Carbon ChemistryMolecular Formula

CH4

C2H6

Carbon Chemistry

C4H10C4H10

C4H8 C4H8

Carbon Chemistry

Carbon Chemistry

Structuralformula

Methane

H H

H

H H H

H

H

Ball-and-stickmodel

Space-fillingmodel

C

C

The 4 single bonds of carbon point to the corners of a tetrahedron.

H H

HH

H H

Ethane Propane

HH

H H

H

H

H

H

H

H

Carbon skeletons vary in length.

H

H

H

H

H H

H H

H H

H H

H H

H H

H

H

H

H

H

H H H H

H

H

C

HH H

H H

H H

H

H

H

H H

H

H

HH

H

H

H H

H

H

Butane Isobutane

Skeletons may be unbranched or branched.

1-Butene 2-Butene

Skeletons may have double bonds, which can vary in location.

CC C

C

CC

H

CC

C

CC

C

Cyclohexane Benzene

Skeletons may be arranged in rings.

C C C C C

C C C C

C

C CC

CCC C CCCH H

Summary: Carbon Chemistry

4 Covalent Bonds

Variable Length

Unbranched or Branched

Single or Double Bonds

Rings

Functional Group

StructuralFormula

HS

P

O–

O

O

HC

H

H

OH

O

OHC

H

HN

CO

C

H

H

CH

H

H

OH

CH

H

HC

O

OH

H

CH3

OH

CCHO NH

CH

H

HHC

O

CHOH

H HS HC

H

CH

OH

HC

OH

H HOC

H

P

O

C

O

C

O

HHC

H

O–

O–

O–

O–

FUNCTIONAL GROUPS Hydroxyl

Carbonyl

Carboxyl

Amino

Sulfhydryl

Phosphate

Methyl

HYDROXYL

Carboxyl

Melting Point (C)

C2H6O -114

C2H5O2 17

C2H6O 78

Boiling Point (C)

C2H5O2 118

Functional groups of male and female sex hormones

Male lion

Female lion

Estradiol

HO

OH

OH

OTestosterone

Importance of Functional Groups

H

OH HOH

H OH

Dehydration reaction

H2O

Dehydration synthesis isPolymer Building

A B C D E

A B C D E

Unlinked monomer

Longer polymer

Short polymer

H

H2O

OH

H OHOH H

Hydrolysis

Hydrolysis is Polymer Breaking

Classes of Biologically Important Compounds

CarbohydratesLipidsProteinsNucleic Acids

17

Carbohydrates

Molecules

• 1:2:1 ratio of carbon, hydrogen, oxygen

empirical formula: (CH2O)n

• examples: sugars, starch, glucose

• C – H covalent bonds hold much energy

• good energy storage molecules

Structure of Monosaccharides

C

C

C

C

C

C

C

C

C

C

H

H

H

H

H

H

H H

H

H

H

HO

H

H

H

C

O

HO

OH

OH

OH

OH OH

OH

OH

C O

OH

Glucose Fructose

C6H12O6

CarbonylGroup

HydroxylGroups

19

Carbohydrates

C6H12O6

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H H HHH

OH OH

OHO

OH H

OHO

OH

HOO

OH

OH H

HH

HO

H H

HH

OH

H

OH

OH

OH

H

H

HO

CH2OH

HH

H

OH

O

GalactoseFructoseGlucose

RiboseGlyceraldehyde

3-carbonsugar

5-carbon sugars

6-carbon sugars

Deoxyribose

HH

H

H

H

H

OH

OH

OC

C

C4

5

1

3 2

4

4

4

4

5

5

55

666

1

1

1

1

3

3

2

233

2

2

1

3

2

CH2OH CH2OH

CH2OH CH2OH

CH2OH

H

Monosaccharide Structure

21

Carbohydrates - Disaccharides

-2 monosaccharides linked together by dehydration synthesis

-used for sugar transport or energy storage

-examples: sucrose, lactose, maltose

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CH2OH

Starch: chain of -glucose subunits

HO

OH

OH HH

H H

H

O O O O O

HOOH

OH HHH

H

H

H

O

Cellulose: chain of - glucose subunits

OH

OH HHH

H

H OH

OH HH

HH

H OH

OH HH

H H

H OH

OH HHH H

H

O

Plantcell wall

HH

H

OH

OHH

OH

OHO O O

O O

14

4 1

form of glucose

form of glucose

4 1

14

H OH

H

O HOH

H H

OO

OH

O

HOH

HOHH

H O

CH2OH CH2OH CH2OH CH2OH

CH2OHCH2OH

CH2OH

CH2OH

CH2OH

OHHHH

Cellulose

Starch

Polysaccharides – Complex Carbohydrates

Glycogen

23

Carbohydrates

Polysaccharides

-long chains of sugars

-used for energy storage

-plants use starch; animals use glycogen

-used for structural support

-plants use cellulose; animals use chitin

Properties

Non-polar molecules

Not Water soluble

Dissolve in nonpolar solvents

Lipids

1. Fatty acids

2. Triglycerides or neutral fats

3. Phospholipids

4. Steroids, prostaglandins and waxes

Types of Lipids

26

Lipids

Fatty acids are long hydrocarbon chains which may be-saturated -unsaturated -polyunsaturated

Triglycerides (fats)-composed of 1 glycerol + 3 fatty acids

Fatty Acid Structure

Hydrocarbon chain CarboxylGroup

Saturated & Unsaturated Fatty Acids

Cis & Trans Unsaturated Fatty Acids

Structure of a Triglyceride

C

C

C

OH

OH

OH

H

H

H

H

H

C

C

C

Fatty acid

Fatty acid

Fatty acid

H

H

H

H

H

Glycerol

Triglycerides or Neutral Fats

32

LipidsTriglycerides

excellent molecule for energy storagetwice as much energy as carbohydrates

animal fats usually saturated solid at room temperature

plant fats (oils) usually unsaturatedliquid at room temperature

Phospholipid Structure

Hydrophilic Polar HeadHydrophobicNonpolar Tails

Phospholipid bilayer Water

Membrane Structure

Steroids

HydrocortisoneCholesterol

Digitoxin

Steroids

Other Lipids

Waxes

Citronellol Taxol

Terpenes

Prostaglandins

Lipid Functions

1. Long term energy storageTriglycerides

1. ProtectionFat deposits around kidneysProstaglandin (thromboxane) induces clotting &

inflammation responseWaxes on leaf surface

2. Synthesis: hormonesCholesterol

Classes of Biologically Important Compounds

Proteins

40

Proteins

Enzyme catalysts

Transport

Motion

Defense

Support

Regulation - insulin

Calcium storage

41

Proteins

Proteins are polymers of amino acids.

Amino acids

-20 different amino acids

-joined by dehydration synthesis

-peptide bonds connect amino acids

Amino Acid Structure

Carboxyl Group

Amino Group

Nonpolar Amino Acids

Amino Acid Structure

Amino Acid Structure

Polar Uncharged

Polar Charged

Amino Acid Structure

Amino Acid Structure

Aromatic

Protein Synthesis

Proteins Have Four Levels of Organization• Primary ..\

• Secondary• Tertiary• Quaternary

N N N

H

H

H

H

H H

H

C C C C C C N C C N CCC

O

OO

O H H

OH H

R

R

R R

R R

Primary Protein Structure

1

Chain of amino acids

Secondary Protein Structure

Flexible e.g. wool

Tensile strength e.g. silk

Tertiary Protein Structure

1. structural regions within a larger protein 2. folds into stable areas3. Modular units of 100 to 250 amino acids4. Domains are functional regions of a protein

Tertiary Structure: Domains

1. Hydrogen Bond

2. Disulfide bridge

3. Ionic bond

4. Van der Waals attraction

5. Hydrophobic Exclusion

Bonds Stabilize Protein Structure

54

ProteinsDenaturation is a change in the shape of a

protein, usually causing loss of function.

-may involve complete unfolding

-caused by changes in the protein’s environment

-pH

-temperature

-salt concentration

Normal (Good) PrPC43% -helix

Prion (Bad) PrPSc30% -helix43% -sheet

Normal Protein Folding is Critical to Function

Mistake in tertiary protein structure

Creutzfeldt Jacob Disease

Chronic Wasting Disease

Bovine Spongiform encephalopathy(Mad Cow Disease)

Fig. 3.8h(TE Art)

Quaternary ProteinStructure

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58

Protein Structure

Primary

Secondary

Tertiary Quaternary

Secondary

Nucleic Acids

Nucleic Acid = polymer of nucleotides

Types of Nucleic Acids Deoxyribonucleic Acid = DNA

Genetic material

Ribonucleic Acid = RNA Protein synthesis

Fig. 3.14(TE Art)

Phosphate group

Sugar

Nitrogenous base

N

N

O

P CH2

O

–O

O–

OH ROH in RNA

H in DNA

O

N

NH2

N

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A Nucleotide is a monomer of a nucleic acid

Nitrogen Bases of Nucleic Acids

Nucleic Acid Structure

Fig. 3.16(TE Art)

P

P

P

P

P

P

P

P

C

C

G

G

A

A

T

T

P

OC G

5’ end

3’ end

OH

P

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DNA StructureDouble Helix

Paired Nitrogen Bases

Hydrogen bonds

Sugar-phosphate "backbone"

Nucleotide

RNA Structure

Ribose (sugar)

NitrogenousBases

G

G

C

A

A

U

U

P

P

PP

P

P

P

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Phosphate

Triphosphate group

5-carbon sugar

Nitrogenous base(adenine)

OP CH2

O

O

O–

P

O

O

O–

P

O

–O

O–

OH OH

OO

NH2

N

N

N

N

Adenosine Triphosphate

ATP