The Molecules of Life

Organic Compounds

• What does organic mean?– No pesticides? – Environmentally friendly farming?

– In biology, organic = carbon based molecules.

Hydrocarbons

• Hydrocarbons are long chains of carbons bonded to hydrogen atoms– C-H bond = high energy– Hydrocarbons are a good energy source

Octane is a hydrocarbon. It is one of the main components of gasoline.

Fats are mostly hydrocarbons

Hydrocarbons

• Why does our body store fat?– C-H bonds are high energy– Fat is an efficient way to store a lot of energy in a

small molecule (9 Calories/gram)– Excess calories fat

Functional Groups

• Functional groups are common groupings of atoms that give molecules predictable properties

Carboxyl group-makes molecules acidic

Amino group-makes molecules basic

Alcohol!

• All alcohols are carbon based compounds with a hydroxyl group

hydroxyl group

ethanol(drinking alcohol) Is sugar an alcohol?

Carbonyl group

• A carbonyl group consists of a carbon atom double bonded to an oxygen atom

AcetoneHave you ever used acetone?

Carboxyl group

• A carboxyl group is a carbonyl group + an alcohol group– Carboxyl groups make many molecules acidic. – Molecule with carboxyl group = carboxylic acid

Ethanoic acid = vinegar

Amino group

• Nitrogen bonded to two hydrogens– Makes molecules basic (opposite of acidic)

Amino acidBuilding block of proteins

Phosphate group

• Phosphate group = phosphorus bonded to four oxygen atoms– Used in DNA backbone– Used in ATP

ATP

Methyl group

• Methyl group = carbon bonded to three hydrogens– Sometimes written CH3

How many methyl groups does acetone have?

Testosterone v. Estradiol

• A few functional groups can make a big difference!

testosterone estradiol (estrogen)

Can you spot the differences?

Polymers

• A polymer is a large molecule made of many similar building blocks strung together– Each building block is called a monomer

Proteins are polymers made of amino acids DNA is a polymer of nucleic acids

Building Polymers

• Polymers are put together by dehydration synthesis– Dehydration = lose water– Synthesis = putting together

Dehydration Synthesis

• Proteins are made by dehydration synthesis– Building blocks = amino acids

Synthesizing proteins from amino acids

Dehydration Synthesis

• Starches are polymers of simple sugars– Sugars are joined by dehydration synthesis

Hydrolysis

• Hydrolysis is the disassembly of polymers by adding water back in– It is the opposite of dehydration synthesis

Hydrolysis of proteins

Hydrolysis of starches

Lactose Intolerance

• Lactose intolerance is the inability to digest milk and dairy products– Consumption leads to nausea, abdominal

discomfort, flatulence, diarrhea– 75% of adults worldwide have partial or full

lactose intolerance

lactose

Lactose Intolerance

• Why are some people lactose intolerant?– Their bodies are incapable of hydrolyzing lactose– Lactose cannot be absorbed by the body unless

broken up into simple sugars– It accumulates in the intestines where bacteria

digest it and release gas (which makes you sick and bloated)