9.3 Polymers

Couplers that interlock connect one railroad car to another. Many cars can be joined together to form a train, because there are couplers on both ends of a car.

9.3 Polymers

A polymer is a large molecule that forms when many smaller molecules are linked together by covalent bonds.

• The smaller molecules that join together to form a polymer are monomers.

• In some polymers, there is only one type of monomer. Other polymers have two or more kinds of monomers.

9.3 Polymers

What is one way that polymers can be classified?

Polymers can be classified as natural polymers or synthetic polymers.

9.3 Polymers

Many important types of biological molecules are natural polymers. Organisms produce these polymers in their cells.

Synthetic polymers are developed by chemists in research laboratories and manufactured in factories.

Both types of polymers have industrial uses. Silk and cotton fabrics are woven from natural polymer fibers, while polar fleece is made from a synthetic polymer.

9.3 Polymers

What are three examples of synthetic polymers?

Synthetic Polymers

Rubber, nylon, and polyethylene are three examples of compounds that can be synthesized.

9.3 Polymers

Rubber• The sap collected from rubber trees in tropical

regions contains rubber. • Chemists produced a synthetic rubber, using

hydrocarbons from petroleum. • Natural rubber and synthetic rubbers contain

different monomers and have different properties.

Synthetic Polymers

9.3 Polymers

Nylon• Research to make artificial silk led to nylon,

which has properties not found in natural polymers.

• Nylon fibers are very strong, durable, and shiny.

• Nylon is used in parachutes, windbreakers, fishing line, carpets, and ropes.

Synthetic Polymers

9.3 Polymers

Polyethylene

Polyethylene forms when ethene (or ethylene) molecules link head to tail.

The number of carbon atoms in a polyethylene chain affects the properties of the polymer. The more carbon atoms in the chain, the harder the polymer is.

Synthetic Polymers

9.3 Polymers

A Rubber is used to manufacture tires.

B Nylon fibers are strong and do not wear out easily.

C Hard plastic shapes can be made from a polyethylene polymer.

Synthetic Polymers

9.3 Polymers

What are four types of polymers that organisms can produce?

Natural Polymers

Four types of polymers produced in plant and animal cells are starches, cellulose, nucleic acids, and proteins.

9.3 Polymers

Starches

Simple sugars have the formula C6H12O6. They can

exist as straight chains or rings. Fructose and glucose can react to form sucrose (table sugar).

Glucose monomers join to form starches as shown below.

Natural Polymers

9.3 Polymers

Simple sugars, slightly more complex sugars such as sucrose, and polymers built from sugar monomers are all classified as carbohydrates.

Typically, a starch contains hundreds of glucose monomers. Plants store starches for food and to build stems, seeds, and roots.

Natural Polymers

9.3 Polymers

All the foods shown contain starch, which is a polymer of the simple sugar glucose.

Natural Polymers

9.3 Polymers

Cellulose• The carbohydrate cellulose is the main component

of cotton and wood.• Cellulose molecules contain 3000 or more glucose

monomers. • Cellulose gives strength to plant stems and tree

trunks.

Natural Polymers

9.3 Polymers

Nucleic Acids

Nucleic acids are large nitrogen-containing polymers found mainly in the nuclei of cells. There are two types of nucleic acid, deoxyribonucleic acid (DNA) and ribonucleic acid (RNA).

Nucleic acids in each cell of a plant or animal store information about its structures and functions.

Natural Polymers

9.3 Polymers

The monomers in a nucleic acid are nucleotides. • A DNA nucleotide has three parts: a phosphate

group, deoxyribose sugar, and an organic base. • When two strands of DNA line up, pairs of bases are

arranged like the rungs of a ladder.

Natural Polymers

9.3 Polymers

The strands in DNA are held together by strong intermolecular attractions between hydrogen atoms on one strand and nitrogen or oxygen atoms on the other strand.

• The strands twist around each other in a structure called a double helix.

• The order of the base pairs in a strand is a code that stores information that is used to produce proteins.

Natural Polymers

9.3 Polymers

Natural Polymers

9.3 Polymers

Proteins

Organic acids contain a –COOH group, and organic bases contains an –NH2 group.

An amino acid is a compound that contains both carboxyl and amino functional groups in the same molecule.

Natural Polymers

9.3 Polymers

There are about 20 amino acids that your body needs to function. They include glycine and phenylalanine.

Natural Polymers

9.3 Polymers

Your cells use amino acids as the monomers for constructing protein polymers.

• A protein is a polymer in which at least 100 amino acid monomers are linked through bonds between an amino group and a carboxyl group.

• The instructions for making proteins are stored in DNA.

• Your body may contain as many as 300,000 different proteins.

Natural Polymers

9.3 Polymers

These foods are all good protein sources.

Natural Polymers

9.3 Polymers

Assessment Questions

1. A synthetic polymer that can be formed into strong fibers suitable for making cloth and rope is a. silk.

b. high-density polyethylene.

c. natural rubber.

d. nylon.

9.3 Polymers

Assessment Questions

1. A synthetic polymer that can be formed into strong fibers suitable for making cloth and rope is a. silk.

b. high-density polyethylene.

c. natural rubber.

d. nylon.

ANS: D

9.3 Polymers

Assessment Questions

2. The strong natural fiber, cellulose, is a polymer made of long chains of what type of molecule? a. amino acidb. organic basesc. hydrocarbonsd. sugar

9.3 Polymers

Assessment Questions

2. The strong natural fiber, cellulose, is a polymer made of long chains of what type of molecule? a. amino acidb. organic basesc. hydrocarbonsd. sugar

ANS: D

9.3 Polymers

Assessment Questions

1. A large molecule that forms when many smaller molecules are linked together by covalent bonds is a monomer.

TrueFalse

9.3 Polymers

Assessment Questions

1. A large molecule that forms when many smaller molecules are linked together by covalent bonds is a monomer.

TrueFalse

ANS: F, polymer