Chapter 5

Organic Macromolecules

Polymerization is…

– the forming of large organic compounds (polymers) by the joining of smaller repeating units called monomers

M

MM

How does polymerization occur?

By Dehydration Synthesis: the removal of a water molecule to form a new bond.

HOH

H2O

HO H

HHO

Short Polymer Monomer

Dehydration removes a water molecule forming a new bond

1 2 3

1 2 3 4

How are polymers broken?

HOH

H2O

HO

H

H

HO

Short Polymer Monomer

Hydrolysis adds a water molecule to break a bond

1 2 3

1 2 3

4

• by hydrolysis - literally, “Water Splitting”

• Add water to break bonds

4 Types of Organic Polymers

1) Carbohydrates

2) Lipids

3) Proteins

4) Nucleic Acids

Carbohydrates• Formula (CH2O)n • 2:1 ratio of H:O• Carbonyl Groups• Ring form in (aq) solution• Important Energy Source• Cellular Structures• Monomer:

– Monosaccharides

• Polymers: – Disaccharides– Polysaccharides

Monosaccharides

Monosaccharides (simple sugars) – Contain 3-7 Carbons each

• Examples: Glucose, Galactose, FructoseGlucose

DisaccharidesDisaccharides (two sugars) – joined by

dehydration synthesis

• Examples: Sucrose, Maltose, Lactose– Maltose = Glucose + Glucose– Lactose = Glucose + Galactose

Sucrose

Glucose Fructose

Polysaccharides

Polysaccharides (many sugars, usually thousands)

• Examples: Starch, Glycogen, CelluloseStarch CelluloseChloroplast Starch

Glycogen

Liver Cell

Plant Cells

Cellulose

Starch and Cellulose Structures(Plant Polysaccharides)

ά – linkages (cis- formation) are easily hydrolyzed, while β - linkages (trans-formation)are not

Glycogen and Chitin (Animals Polysaccharide)

• Glycogen = glucose polymer – Stored in

liver/muscle

• Chitin = structural polymer in exoskeletons

Lipids

• Elements: C, H, O with H:O ratio > 2:1• Hydrophobic• Lipids function in:

– Energy (E) storage, – forming cell membranes, – and as chemical messengers

(ex. hormones)• Monomers: glycerol, fatty acids, sometimes

phosphate groups• Polymers:

– Fats (triglycerides)– Phospholipids– Steroids

TriglyceridesFats (Triglycerides)

– Glycerol + 3 Fatty Acids– Saturated = No Double Bonds (solid)– Unsaturated = Double Bonds (liquid)

OH

OH

OH

OH

OH

OH

Ester Bonds

PhospholipidsPhospholipids

– Glycerol with Phosphate Head + 2 Fatty Acid Chains

– Amphiphilic (“Both” “lover”)• Hydrophilic head• Hydrophobic tail

– Forms 2 layers in water– Makes up cell membranes

Phosphate

Glycerol

Fatty Acids

Steroids

OH

O

Testosterone

HO

O

Estrogen

AKA Sterols– Lipids whose Carbon Skeleton consists of 4

fused rings– Includes:

• Hormones• Cholesterol• Cortisol

– Makes up cell membranes

HOOH

O

O

OH

Proteins (Polypeptides)

• Polymers of AA– 20 AA, all varied in their “R” groups– 9 essential AA can not be made by the body

• 50% of dry weight of organisms

• Varied fcns: enzymatic, structural, hormonal, transport, storage, mvmt, defense, etc.

• Protein function unique with 3-D shape

Proteins• Protein monomers are called amino acids

– Peptide Bond: Bond between 2 Amino Acids:

HH22OO

Side Chains

Backbone

R Group =

Amino end Carboxyl end

Protein Structure

• Primary

• Secondary

• Tertiary

• Quarternary

Figure 5.24 Review: the four levels of protein structure

Polypeptides fold and twist to form a specific shape to create a functional protein

Primary Structure

AA sequence

Secondary Structure

• AA H-bonded at backbone

• (no interaction btwn side chains)

• α – Helix• β - Pleated Sheats

Tertiary Structure

• More Complex Folding

• Interactions btwn side chains– H bonds– Ionic Bonding (+/-)– Hydrophobic

Interactions– Disulfide Bridges

Figure 5.22 Examples of interactions contributing to the tertiary structure of a protein

Quarternary Structure

• 2 or more polypeptide chains assemble

• Ex. Hemoglobin (4 polypeptide chains)

Figure 5.23 The quaternary structure of proteins

Functional Proteins

Hi sweeties, Do you remember

me?

In addition to what you know. I am a substrate.

I am an enzyme. I am going to try to convert you.

I am now a product.

I am a glucose now.

I am a product, too.

I am a fructose now.

I am completely unchanged, and ready for some more sucrose!

I am the active site. The substrate binds

to me.

The twisting and folding into tertiary or quarternary structures creates active sites with a specific shape that fits specific substrates that are responsible for catalyzing reactions

Factors That Affect Protein Formation

• pH• Salinity• Temperature (ex.

Boiled egg)• Denaturization =

unraveling of protein loss of shape and function

• Renaturization can occur, but not always

Figure 5.25 Denaturation and renaturation of a protein

Nucleic Acids

• Nucleic Acids– Informational Polymers: Code for all of the

proteins in an organism– Monomers: Nucleotides

• Phosphate Group• Pentose 5-C Sugar

– Ribose or deoxyribose

• Nitrogenous base– Purines (A, G)– Pyrimidines (T, C, U)

Nucleic Acids• Polymers

– DNA – RNA (tRNA, mRNA,

rRNA)

• DNA directs RNA synthesis

• RNA directs protein synthesis

Base Pairing Rules

• DNA Base Pair RulesC = G

A = T

• RNA Base Pair RulesC = G

A = U