NOTES 8 – Polymers & Biochemical Compounds

What is a polymer? Polymer – a large molecule formed by linking together many small molecules (monomers) Monomers – small molecules that make up polymers when linked together Ex. Polyethene (a type of plastic) The prefix poly means “many” The suffix ethene is an alkene with the formula C2H4 Polyethene = “many ethenes”

Natural vs. Man-made Polymers Natural polymers are large organic molecules formed by living organisms Ex. Wood (cellulose), cotton, wool, starch, protein, DNA Man-made polymers are created from natural polymers Ex. Plastics – flexible and easily molded Ex. Fibers – form long, thin strands (nylon, etc.)

Polymer Structure Determines Properties Polymer molecules are like long, thin chains A piece of plastic is made of billions of these chains If the polymer chains are tangled but not connected, the polymer will be flexible Ex. Plastic milk jug (polyethene) - If the plastic is crushed, it does not return to its original shape

Polymer Structure Determines Properties If the polymer chains are connected, or cross-linked, the polymer can stretch and return to its original shape Elasticity – the ability of a polymer to return to its original shape when stretched Ex. Rubber

What are biochemical compounds? Biochemical compound – a naturally occurring organic compound Contains carbon Has a molecular structure Produced by living organisms Essential to life Some are huge polymers Remains change over time into fossil fuels (coal, oil, natural gas) Ex. Carbohydrates, proteins, DNA, lipids (fats & oils)

Carbohydrates Used for cell energy and building material Produced by plants (photosynthesis) Can be small molecules Ex. glucose and fructose (simple sugars) Can be large polymers Ex. Starch is a large plant polymer made of many linked glucose monomers Ex. Glycogen is a large animal polymer made of many linked glucose monomers

Did you know? Cellulose is the main ingredient in plant cell walls and is the most abundant organic compound on Earth - plants produce roughly 100 billion tons of cellulose per year! Paper and cotton are almost 100% cellulose Cows and termites have cellulose-digesting microorganisms living in their digestive systems that enable them to break down cellulose-rich foods like grass (cows) and wood (termites) – you don’t have any!

Foods That Contain Carbohydrates Wheat, pasta, bread, rice, potato, vegetables, fruits, honey Your body breaks down all carbs into glucose, which is used by your cells or stored as glycogen (a polymer) in your liver until it is needed

Proteins Large polymers made out of many linked amino acid monomers There are 20 unique amino acid monomers Different amino acid combinations make different proteins Make up structures of organisms Speed up chemical reactions Act as cell to cell messengers Ex. Insulin – controls blood glucose levels Ex. Lactase – digests milk sugar (lactose)

Foods That Contain Proteins Meat, dairy products, eggs, beans, nuts When you eat foods that contain proteins, your digestive system breaks down the proteins into individual amino acids Your cells bond the amino acids in a different order to form whatever protein your body needs

DNA – Deoxyribonucleic Acid Large polymer made out of many linked nucleotide monomers Has double helix structure (twisted ladder) Found in most living cells Carries genetic code (protein-building instructions) Determines organism characteristics Is able to be copied exactly and passed from one generation to the next