Chapter 3

Biochemistry

I. Carbon Compounds

• Inorganic vs. Organic• Inorganic compounds

do not contain carbon atoms

• Organic compounds contain carbon atoms

Carbon Bonding

• Carbon has 4 electrons in its outer shell– It wants to gain 4 more to become

stable with 8– Carbon readily forms four covalent

bonds with atoms of other elements– Carbon is unique from other

elements because it can bond with other carbon atoms

– Because of all the preceding, carbon is able to form an enormous variety of organic bonds

• Single Bond-sharing one pair of electrons

• Double Bond-sharing two pair of electrons

• Triple Bond-sharing three pair of electrons

Functional Groups

• Clusters of atoms that influence the properties or characteristics of the molecule

Large Carbon Molecules

• Monomers- a simple molecule, smallest subunit

• Polymers- made of repeating monomers

• Macromolecules- made up of large polymers

• Condensation Reactions- release a molecule of water to form a bond

• Hydrolysis- water

• is added to break

• a polymer

You Down with ATP?

• Cells run on energy in the form of ATP– Adenosine triphosphate– Phosphate groups

attached by covalent bonds, which store high amounts of energy

II. Molecules of Life

• Carbohydrates

• Lipids

• Proteins

• Nucleic Acids

Carbohydrates

• Composed of carbon, hydrogen, and oxygen in a ratio of 1C:2H:1O, Serve as a source of energy or used for structural materials

• Monosaccharides- a monomer of a carbohydrate (glucose, fructose and galactose)

• Disaccharides- two monosaccharides or a double sugar (glucose + fructose = sucrose)

• Polysaccharides- three or more monosaccharides

• Animals store glucose in the form of the polysaccharide glycogen

• Plants store glucose as the polysaccharide starch

• Strength and rigidity in plants is caused by the structure of the polysaccharide cellulose

Proteins

• Composed mainly of carbon, hydrogen, oxygen, and nitrogen, provide structure for cells

• Amino acids-monomers of protein (building blocks)

• Dipeptides-two amino acids held together by a peptide bond

• Polypeptides- three or more amino acids, held together by peptide bonds

Amino Acids

• 20 different amino acids• All contain

– Central carbon

– Amino group

– A carboxyl group (COOH)

– A single hydrogen

– R group (the only thing different between the 20 amino acids) influences the properties of the amino acid

Peptide Bond

• Covalent bond linking two amino acids

• A condensation reaction (water is formed and released)

• Long chains of amino acids has positive and negative regions which fold to give protein molecules unique shapes

• The shapes can be denatured when heated

Enzymes• RNA or protein

molecules that act as biological catalysts

• Depend on the fit between– Substrate

– Enzymes active site

Lipids

• Long chains of carbon with many hydrogens

• Function is to store energy

• Include: fatty acids, triglycerides, phospholipids, waxes, steroids

Fatty Acids

• Unbranched carbon chains that make up most lipids

• Long chain of carbon with a carboxyl group at one end

• Carboxyl end is polar and therefore hydrophilic• Hydrocarbon end is nonpolar and therefore

hydrophobic• Fatty acids include triglycerides, phospholipids,

and waxes

• Saturated Fatty Acids– Carbon atoms fully saturated with hydrogens

• Unsaturated Fatty Acids– Carbon atoms with double bonds

Triglycerides

• 3 molecules of a fatty acid joined to one molecule of the alcohol glycerol

• Saturated triglycerides have high melting points and are hard at room temp (butter and fats in red meat)

• Unsaturated are usually soft or liquid at room temp and found in plant seeds (olive oil)

Phospholipids

• Two fatty acids attached to a molecule of glycerol and a phosphate group attached to the third carbon of the glycerol

• Help make up the cell membrane

• Lipid bilayer– Hydrophobic head– Hydrophilic tail

Waxes

• A long fatty acid chain connected to a long alcohol chain

• Waterproof• Help form protective

coating in plants and animals (earwax)

Steroids

• Four fused carbon rings with various functional groups

• Hormones• Cholesterol

Nucleic Acids• DNA

– Contains information that determines the characteristics of an organism and directs cell activities

• RNA– Stores and transfer information of DNA to make

proteins

• Composed of nucleotides– Sugar– Phosphate– Base

Review

• What do all organic compounds contain?– Carbon

How many electrons are shared in a double bond?

• 4 electrons (aka 2 pair)

How many electrons does carbon want to gain?

• 4 electrons

What is the smallest subunit

• Monomer

• What is the monomer of carbohydrates?– monosaccharides

• What is the monomer of proteins? – Amino acid

• How do animals store glucose?– Glycogen

• How do plants store glucose?– Starch

• What are the polymers of carbohydrates– polysaccharides

• What are the polymers of protein?– Polypeptides

• What are the only two macromolecules that contain nitrogen?– Proteins

– Nucleic Acids

• Which macromolecule is nonpolar?– Lipids