Properties of Water

Water molecules are polar so hydrogen bonds form between them.

An average of 3.4 hydrogen bonds are formed between each molecule in liquid water. This forms an arrangement known as a water lattice.

• Life – Sustaining PropertiesUnusual ability to resist changes in temperature.High internal cohesion (molecules sticking together) creating surface tension.It’s a great solvent (dissolves stuff).

Carbon

Carbon BondingCarbon atoms form 4 covalent bonds to fill their outer electron shells. This allows them to form a variety of chain and ring structures that form the backbone of all biological molecules.

• These are known as organic molecules.

• Molecules consisting of carbon and hydrogen are called hydrocarbons.

Functional Groups in Biological Molecules

• Hydroxyl GroupsConsist of an oxygen atom linked to a hydrogen (--OH).They give the molecule they are attached to a polar nature.Key component of alcohols.

• Carbonyl Groups

A carbon atom linked to an oxygen atom by a double bond (C=O).

Important molecules for cellular energy.

• Carboxyl GroupsA combination of a carbonyl group and a hydroxyl group. (--COOH).Characteristic functional group of organic acids because it releases hydrogen in water solutions.Examples are citric and acetic acid.

• Amino Groups

Contain a nitrogen atom bonded to two hydrogen atoms

(--NH2).

Functional group of amino acids which are the building blocks of proteins.

• Phosphate GroupsConsists of a central phosphorus bound to oxygen atoms and hydroxyl groups (--OPO3

2-).Form chemical bridges between organic molecules.Added or removed to release energy.Control chemical activity of many proteins.

• Sulfhydryl Groups

A sulfur atom is linked on one side to a hydrogen atom and on the other to a carbon chain (-SH).

Act a molecular fastener holding protein molecules in their folded form or linking protein subunits into larger structures.

Biological Molecules

CarbohydratesMonosaccharidesSmallest carbohydrate molecules.Consist of 3, 5, or 6 carbon atoms bonded to hydrogen.Can be linear or ring forms.Many exist as isomers, meaning same chemical formula but different molecular structures causing them to react differently.

• DisaccharidesConsist of two monosaccharides linked together by a dehydration synthesis reaction.Sucrose (fructose + glucose) is the sugar transported in plants and crystalized to form table suger.Lactose (glucose+galactose) is sugar found in milk.

• PolysaccharidesLong chains of monosaccharides linked to form macromolecules.Result from the polymerization of monosaccharide monomers into larger polymers.

• Plant Starches

Storage form of carbohydrates in plants.

Long chains of glucose molecules that are digestible by humans.

• Glycogen

Storage form of carbohydrates in animal livers.

Highly branched chains of glucose molecules.

• CelluloseMost abundant carbohydrate in nature.Primary structure of plant cell walls .Can be digested by herbivores, but not by humans. Still important fiber for healthy digestive functions.

• ChitinTough carbohydrate chains with nitrogen-containing groups.Main component of the shells of arthropods such as insects and crabs.Also cell walls of fungi such as mushrooms.

Lipids

• Neutral LipidsLipids are a group of water-insoluble, nonpolar molecules made up mostly of hydrocarbons.Neutral lipids have no charged groups at cellular pH.Consist of fats, oils, and waxes made from a glycerol backbone and 3 fatty acid side chains.

• Fatty Acids

Single hydrocarbon chains with a carboxyl group at one end.

If it contains the maximum number of hydrogen atoms is considered saturated.

Main component of fats which are semisolid.

If one or more double bonds link the carbon atoms it is considered unsaturated.These are the main component of oils which are liquid a biological temperatures.Unsaturated lipids are considered healthier in the human diet than saturated.

• PhospholipidsFormed from a glycerol backbone attached to two fatty acid side chains and a polar phosphate group.In a polar environment (such as water) phospholipids assume arrangements in which only their polar ends are exposed to water. This is the reason cell membranes form a lipid bilayer.

• SteroidsGroup of lipids with structures based on four carbon rings.Most abundant are the sterols which have a single –OH group linked to one end of the ring framework and a complex, nonpolar hydrocarbon chain at the other end.

Nucleotides and Nucleic Acids

• NucleotidesA nucleotide consists of three parts linked together by covalent bonds:1. a nitrogenous base (either a purine or a pyrimidine)2. a five-carbon, ring-shaped sugar (either ribose or deoxyribose)3. one to three phosphate groups

• Nucleotide Functions

Important molecules such as ATP (adenosine triphosphate) and GTP (guanosine triphosphate) are the primary molecules that transport chemical energy in cells.

Nucleotides are the building blocks (subunits) of nucleic acids.

• Nucleic AcidsDNA (deoxyribose nucleic acid)Consists of two nucleotide chains wrapped around each other to form a double helix.Sugar (deoxyribose) and phosphate molecules make up the backbone and pairs of nitrogen bases make up the center.Nitrogen bases come in four varieties: adenine, guanine, cytosine, and thymine.

• RNA (ribonucleic acid)

Single stranded chain of nucleotides bound together by sugar (ribose) and phosphate bonds.

Nitrogen bases are the same as DNA except uracil replaces thymine.

Water and Carbon Compounds Vocabulary Terms

1. Polarity

2. Organic

3. Carbohydrates

4. Starch

5. Glycogen

6. Chitin

7. Saturated vs Unsaturated Fats

8. Phospholipids

9. Nucleotides

10. Nucleic Acid