Organic Compounds

(Biomolecules/Macromolecules)

Many organic compounds in biology are polymers

What is a polymer ?

• A polymer is made up of many repeating units called monomers

• Look at the prefixes mono and poly (what do they mean?)

Polymer basics

• Usually, monomers are connected together through the process of dehydration synthesis (condensation synthesis or condensation reaction)

• Conversely, polymers are broken apart using hydrolysis (think: “hydro lysis”)

• Helper molecules called enzymes are often needed for this process

Why are polymers important?

• An immense variety of polymers can be built from a small collection of monomers.

• The order and number of monomers in a polymer will determine the function of the polymer.

The Four Big Polymers in Bio…

• Carbohydrates

• Lipids* (technically not a polymer)

• Proteins

• Nucleic Acids

Carbohydrates

Functions:

energy source

structure

Carbohydrates

• Contains C,H,O sometimes in a 1:2:1 ratio:

(C6H12O6)

• Monomers of carbohydrates are simple (single) sugars (mono saccharides):

glucosefructose galactose

The monosaccharides…

Glucose is the preferred energy source for most all organisms.

Note the chemical formula for all three of these substances is C6H12O6

The unique properties of each of these substances is due to the arrangement of atoms

around each other.

• Dimers: (double sugars or disaccharides)

includes:

sucrose

maltose

lactose

Sucrose: a double sugar (disaccharide)

• Polymers (complex carbohydrates, polysaccharides)

includes:

starch

cellulose

chitin

glycogen (animal starch)

Starch formed from dehydration synthesis of glucose

Comparison of starch and cellulose

Note the opposite arrangements of glucose units in cellulose that make it unable to be digested directly by most vertebrates.

Comparison Between the Structural Differences Between Chitin and Starch

Energy content of “carbs”:

• 4 calories/gram for the carbohydrates we can digest– In order for us to be able to get the carbohydrate into the

bloodstream to be turned into energy, it needs to be broken down into a monosaccharide (the smallest type of sugar)

• 0 calories for the carbs we can’t digest:» Chitin» Cellulose*** even though we can’t digest cellulose,

we still need it…why?