Biomolecules

Ch - 2The Molecules of Life

Molecules are combinations of atoms

• What are the 4 elements that make up 96% of living matter?

• Carbon C• Oxygen O• Nitrogen N• Hydrogen H

Importance of Carbon

• Carbon has 4 valence electrons• carbon can create strong skeletons or backbones

Carbon bonds with Carbon

• Biomolecules have carbon backbones – They are organic molecules

• C-skeletons: straight chain, branched chain, ring

Carbon bonds with Hydrogen

• Hydrocarbons are molecules composed of only hydrogen and carbon

• Are hydrophobic

Carbon bonds with functional groups

• Functional groups are groups of atoms that interact in predictable ways

• Functional groups attach to carbon backbones to create biomolecules

Hydroxyl Group

• alcohols• polar– Hydrophilic – Soluble in water

Found in sugars

Carbonyl

• Ketones (within) and aldehydes (on the end)• Polar• Found in sugars

Carboxyl Group

• carboxylic acids• Polar• Acidic • Found in fatty acids and proteins

Amino Group

• Amines• Polar• Basic• Found in amino acids (proteins)

Phosphate Group

• Store/transfer energy• Polar; water soluble• Found in nucleic acids • Found in ATP (adenosine triphosphate) = cell

energy

Monomers & Polymers

• Biomolecules are combinations of smaller molecules called monomers

• Monomers link together to form polymers

Building and breaking polymers

• dehydration synthesis = monomers combined to make polymers

Building and breaking polymers

• Hydrolysis = polymers are broken into monomers

4 Biomolecules

• All polymers are classified into one of 4 biomolecules:– Carbohydrates– Lipids– Proteins– Nucleic Acids

Carbohydrates!

Carbohydrates

• Ring shape • Provide and store energy; building material in

plants

Carbohydrates

• Carbs are hydrophilic– Full of hydroxyls and carbonyls

Monosaccharides

• 1 ring• Example: Glucose (C6H12O6)• energy source

Disaccharides

• Double Sugars (oxygen bridge)• Example: Sucrose • immediate energy or stored

Polysaccharides

• Long polymer of sugar monomers• Complex carbs• Starch: chain of glucose monomers– used by plants as sugar storage– Animals can break down starch to release glucose

and energy

Polysaccharides

• Glycogen– Used by animals to store extra sugar– Stored in the liver

Polysaccharides

• Cellulose– Used by plants for building material– Most animals cannot break down cellulose; passes

through body as fiber• Chitin– Used by fungi for building material

Lipids!

Lipids

• ALL hydrophobic

Lipids: Phospholipids

• Phospholipids: form cell membranes

Lipids

• Fats (triglycerides) 3 C backbone (glycerol) attached to 3 long chains of hydrocarbons (fatty acids)

• Store energy, cushion organs, insulate

Lipids: Fats• Saturated fats– all fatty acids have maximum H atoms– Solid at room T

• Unsaturated fats– One or more double bond in fatty acid chain, causing in to

kink

Which do you want to limit in your diet?

Lipids: Steroids

• C-skeleton of 4 fused rings• Steroids are chemical signals– Cholesterol = essential in cell membranes; building

block of other steroids

Proteins!

When there is something to do, it is a protein that does it.

Proteins

• Proteins have many important functions. Some are:– Antibodies– Receptors– Enzymes – Neurotransmittors– Energy Storage– Build and Repair muscles and tissue

Amino Acids

• Proteins are polymers made up of monomers called amino acids

• Amino Acids consist of one central C bonded to 4 partners:– H-atom– Carboxyl– Amino– An “R-group”

Polypeptides

• Amino acids link together forming peptide bonds

Protein Structure

• Polypeptides take shape to from a protein.• Each protein has its own unique 3-D shape

that determines its function• The shape of a protein is determined by how

its amino acids interact

Denaturation

• Proteins can be unraveled and changed by changes in temp, pH, or other changes in environment

Enzymes

Protein: Enzymes

• An enzyme is a biological catalyst• Lower the activation energy of a specific

reaction– allow chemical reactions in cells to occur at

normal temperatures

Protein: Enzymes

• Each enzyme has a specific job• Used again and again• Ability depends on shape

Protein: Enzymes

• Substrate molecules fit into active site, enzyme molds around substrate– enzyme-substrate complex

• Enzyme breaks up the substrate