Anything that occupies space and has mass. 

Matter can exist as a gas, liquid, or solid and is composed of elements.

1. Protons-have a positive electrical charge
2. Neutrons-have a negative electrical charge
3. Electrons-have no electrical charge, neutral

(these particles do not retain the physical and chemical properties of the element when they are isolated)

A dense region at the center of an atom consisting of positively charged protons and uncharged neutrons.

Protons and neutrons are the heaviest particles, each having an atomic mass of one.

Formed when atoms share electrons.

Single covelent bonds share one electron, double bonded share two, and triple bonded share three.

1. Synthesis reaction-a new and more complex chemical is made from multiple, simpler chemicals. ex: X+Y>XY
2. Decomposition reaction-a single, complex chemical is broken into multiple, simpler chemicals. ex: XY>X+Y
3. Exchange reaction-certain atoms are exchanged between molecules. ex: WX+YZ>WY+XZ

1. Concentration of reactants
2. Temperature
3. Activation energy
4. Some reactions require the presence of a catalyst or enzyme

• Do not contain hydrocarbon groups 

(hydrogen and carbon bonded together)

• Often have ionic bonding

ex: water, salts, acids, and bases

• Molecules that contain hydrocarbon groups 

• Usually are covalently bonded.

ex: carbohydrates, lipids, proteins, and nucleic acids

• universal solvent
• ideal transport medium
• has a hight heat capacity and a high heat of vaporization
• used for lubrication

• Mineral compounds that have ionic bonding 
• The priciple form of minerals that enter and are stored in the body
• When salts are added to water them immediately ionize
• Salts in their ionic form are known as electrolytes
• Electrolytes are substances that have to ability to transmit an electrical charge

Acids-Ionically bonded substances that release hydrogen ions (H+) in water

Bases-Ionically bonded substances that release a hydroxl ion (OH-) in water

Acids and bases are also electrolytes - when they ionize in water, they can transmit electricity

• Acidity and alkalinity are measured on a pH scale
• The scale ranges from 1 (the most acidic) to 14 (the most basic)
• A pH of 7 in the middle of the scale is neutral

To function properly the tissues and blood in the animal body must maintain a pH of around 7.4, which is slightly basic.

• Weak acids and bases that do not completely ionize in water
• By not allowing excessive hydorgen or hydroxl ions to accumulate, buffers help the cell to maintain a neutral pH.

• Functions: used for energy, storage of energy, and cellular structures
• Monosaccharides: contain three to seven carbon atoms in a chain or ring. 

Example: glucose, chemical formula C6H12O6 

• Disaccharides: two monosaccharides joined together 

Example: glucose + fructose = sucrose. 

• Polysaccharides: combinations of many monosaccharides

Examples: glycogen, starch, and cellulose 

• Functions: used in the body for energy and stored in fat for future energy needs

• Four classes of lipids: 

1. neutral fats
2. phospholipids
3. steroids 
4. eicosanoids

• Neutral fats are also called triglycerides. 
• Contain three fatty acids and a glycerol molecule 
• A glycerol molecule is a modified three-carbon simple sugar.
• A fatty acid is a chain of carbon atoms with one or two hydrogen atoms attached to each carbon by single or double bonds. 

• A fatty acid is called saturated when all the bonds in the hydrocarbon chain are single bonds and as many hydrogen atoms as possible are attached to carbon. 
• A fatty acid is called unsaturated when there are some double bonds between the carbon and hydrogen atoms. 

• Contain two fatty acids attached to glycerol extending in one direction 
• Phosphate group (PO4) attached to a nitrogen-containing compound extending in the other direction
• The phosphate group side is hydrophilic and polar.
• The fatty acid side is hydrophobic and nonpolar.

• Lipids that take the form of four interlocking hydrocarbon rings 
• Hydrophobic and nonpolar 
• Different types of steroids are formed by attaching unique functional groups to the four-ring structure of the molecule.

• Lipids formed from a 20-carbon fatty acid and a ring   structure 
• Prostaglandins: mediate inflammation
• Thromboxane: mediates platelet function 
• Leukotrienes: mediate bronchoconstriction and increased mucus production 

• Proteins are the most abundant organic molecules in the body. 
• Composed primarily of C, O, H, and N
• Made of amino acids
• Functions: used for cell structures and structural body tissues, for controlling chemical reactions, for regulating growth, for transporting molecules, for defending the body against invaders, for catalyzing all reactions occurring in the body 

• 20 different amino acids used by the body 
• Contains a central carbon atom attached to a hydrogen atom, an amino group (NH2), a carboxyl group (COOH) and a side chain (designated by the letter “R”)
• The R group defines each amino acid. 
• The specific combination of amino acids is determined by the cell’s DNA. 
• Two amino acids are linked together by dehydration synthesis. 
• • The carboxyl group of one amino acid links with the amino group of another amino acid via a peptide bond.
• A polypeptide is a chain of ten or more amino acids linked together. 

• Primary structure: the sequence and number of amino acids that link together to form the peptide chain
• Secondary structure: the natural bend of parts of the peptide chain as it is formed in three dimensions
• The most common shapes that chains of amino acids assume are the alpha helix and the beta-pleated sheet.
• Tertiary structure: the overall shape of a single protein molecule

• Quaternary structure: two or more protein chains join to form a complex macromolecule. 

• Structural proteins are stable, rigid, water-insoluble proteins that are used for adding strength to tissues or cells.

Examples: collagen, fibrin, and keratin

• Functional proteins are generally water-soluble and have a flexible, three-dimensional shape that can change under different circumstances.

Examples:  hemoglobin, antibodies, enzymes, 

   and protein-based hormones

• Enzymes are proteins that act as catalysts to speed up a chemical reaction without themselves being altered or destroyed. 
• Enzymes are specific to the reaction they catalyze.
• Substrates are the substances enzymes act upon.
• An enzyme fits its substrate exactly and is itself unaltered at the end of the reaction.

• Enzymatic reactions often take place in a series of reactions, with the products of one reaction acting as the substrate for the next reaction.

• Nucleic acids are the largest molecules in the body 
• Composed of C, O, H, N, and P 
• Two classes of nucleic acids: 

1. DNA (deoxyribonucleic acid) — exists mainly in the nucleus (but also in mitochondria) and is the molecule that contains all the instructions needed by the cell to build protein 
2. RNA (ribonucleic acid) — transfers instructions out of the nucleus and into the cytoplasm of the cell; builds proteins 

• Molecular building blocks of nucleic acids 
• Consist of a nitrogenous base plus a 5-carbon (pentose) sugar plus a phosphate group 
• The sugar in DNA is deoyxribose and in RNA, ribose.
• The nucleic acid is formed by the sugar and phosphate groups joined in a long chain with the nitrogenous base.
• The information needed to produce proteins is determined by the order of the nucleotides.
• A grouping of three nucleotides is the code for a specific amino acid. 
• A gene is a sequence of nucleotides that carries the information to make one peptide chain. 

• The five nucleotides are named for their itrogenous base: 
• Adenine (A), guanine(G), and cytosine (C) occur in both DNA an RNA 
• Uracil (U) occurs only in RNA 
• Thymine (T) occurs only in DNA 

• DNA is constructed of two parallel strands of the nucleotides A, G, C, and T. 
• The strands are connected by hydrogen bonds between the nitrogenous bases. 
• Adenine can bond only with thymine, and guanine can bond only with cytosine. 
• The two strands of bonded nucleic acid twist around each other in a spiral called a double helix.

• RNA consists of a single strand of the nucleotides 

A, G, C, and U. 

• Three types of RNA: 

1. Transfer
2. Messenger
3. Ribosomal RNA 

• Sugars
• Glucose – the primary form of energy in the body, the only usable energy for the brain
• 90 times the chemical energy in ATP
• 1 gram provides 4Kcal of energy
• Protein
• Only a substitute for sugars in the energy spectrum
• 1 gram provides 4Kcal of energy
• Fat
• 1 gram provides 9Kcal of energy

• The energy needed by the body is stored in the phosphate bonds of the ATP molecule.
• ATP is an RNA nucleotide containing adenine with two additional phosphate groups attached.