Chapter 2 Biomolecules

Macromolecules• Biological macromolecules are

defined as large molecules made up of smaller molecules.

• There are 4 classes of macromolecules:– Carbohydrates– Lipids– Proteins– Nucleic acids

Macromolecules• Each macromolecule is made

up of smaller organic molecules.

• These smaller molecules are called monomers.

• Monomers that are bonded together are called polymers.

Carbohydrates•Made of carbon (C), hydrogen (H), and oxygen (O) atoms, always in a ratio of 1:2:1•The key source of energy used by living things.•Carbohydrates are sugar molecules.•The simplest carbohydrate is a monosaccharide (a simple sugar).

–An example of a monosaccharide is glucose.

Carbohydrates•Monomers of monosaccharides bond together to form more complex sugars.

–Disaccharides–Polysaccharides

Polysaccharides• Starch

– A storage polysaccharide found in plants

– Found in potatoes, pasta & bread (wheat)

• Cellulose– A major component of a plant cell

wall.– Found in raw plants/vegetables

(it’s what gives the crispness).– Used to make paper.

• Glycogen– Long term storage of energy for

animals.– Broken into glucose monomers for

energy source.

Carbohydrate Test - Glucose•To test for the presence of glucose we will use the Benedict’s Test. •A positive reaction in a Benedict’s Test is the change of the clear light blue solution to an opaque orange-brown solution in a boiling water bath. •This color change indicates the presence of Glucose in a given solution.

Carbohydrate Test - Starch•To test for the presence of starch, the Lugol’s Iodine Test is used. •This is a simple test in which iodine is added to a given solution. •If iodine added to a solution turns black-blue then starch is present. If the solution remains the color of iodine, reddish-orange, there is no starch present, a negative test.

Lipids• The base elements of these

molecules are C, H and O. • The body stores lipids as

reserve energy. • Lipids function to:

– Insulate our bodies– Protect our bodies– Give us long term energy storage

• Lipids are commonly known as fats, oils and waxes.

Lipids• Lipids are made of one

monomer of glycerol and 2 or 3 fatty acids.

Lipid Test• The best way to test for the

presence of lipids is the Brown Paper Test.

• A substance is placed on a piece of brown paper.

• A positive test for lipid will leave an “oily” spot on the brown paper.

Proteins• Proteins are the most complex and

functionally diverse molecules of living organisms.

• Proteins compose enzymes, blood cells, antibodies and muscle tissue just to name a few and are therefore associated with meat products.

• The base elements of proteins are C, H, O and N.

• The monomers of proteins are 20 different amino acids.

• The main function of proteins is for growth and repair of tissues in the body.

Protein

Monomer

Polymer

Protein Test• We test for the presence of

protein using the Biuret Test. • A violet color is a positive

reaction for protein in a Biuret Test.

Nucleic Acids• There are two kinds of nucleic

acids – DNA and RNA.• DNA carries genetic

information and is responsible for heredity.

• Both are involved in the creation of proteins.

Nucleic Acids• Nucleic acids are made of

monomers called nucleotides.• Nucleotides have 3 parts:

– Sugar– Phosphate– Nitrogen Base

Biomolecules TableCarbohydrates Lipids Nucleic Acids Proteins

Elements

Function (What is it used for?)

Building Blocks(What pieces is it

made of?)

Examples

How do we test for it?

Enzymes

Enzymes• Many slow reactions are essential

for an organism to survive but, are not quick enough to sustain life.

• Biological catalysts are chemical agents that influence the rate of a reaction without changing or affecting the reaction.

• An enzyme is a biological catalyst that allows reactions to occur at much higher rates.

• With the help of enzymes, those slow reactions can occur quickly enough to sustain life.

How do enzymes work?• The amount of energy needed to

begin a reaction is known as the activation energy.

• Enzymes speed up reactions by lowering this activation energy.

• This allows reactions to proceed much faster than they would have with a higher energy barrier.

How do enzymes work?

Enzyme Structure• Enzymes are substrate-specific. • This means they are very “picky” and only

react with specific substrates to form products.

• In a normal enzymatic reaction the enzyme and substrate collide randomly in a solution and join at the enzyme’s active site.

• This collision works much like a lock and key effect.

• The active site has a specific shape that only a particular substrate fits into.

• When the two are joined they react and the substrate is converted into a product.

• Once the reaction is complete the enzyme and newly formed product separate with the enzyme left unchanged.

Enzyme Structure

Enzyme Action• Enzymes can be “turned off” or

made inactive by:– Change in temperature– Change in pH– Removal of substrate– Addition of inhibitors

• This is called denaturation because it changes the shape of the enzyme.