Ch. 2Part 2

The Chemical Level of Organization

Inorganic vs. Organic• Inorganic

– Usually lack carbon– Structurally simple– Include:

• Water• Salts• Acids• Bases

– Exceptions• Carbon dioxide (CO2)

• Bicarbonate (HCO3-)

• Carbonic acid (H2CO3)

• Organic– Always contain carbon– Usually contain

hydrogen– Always have covalent

bonds– Most are large

molecules made up of long chains

Role of Water in the Body

• Most important inorganic compound for life• Almost all chemical reactions in the body need

water to occur• Water is a solvent – dissolves important

substances• Water has high heat capacity – doesn’t change

temperatures easily• Water also acts as a lubricant (mucus) for joints,

food movement, and between thoracic organs

Acids and Bases

• This is also a review• pH scale – 0-14• Acids (0-6)– Dissociate into hydrogen (H+) ions– Example: HCl

• Bases (0-14)– Dissociate into hydroxide (OH-) ions– Example: NaOH

Acids and Bases in the Body

• Buffer system – the body’s ability to control pH of certain fluids

• Example:– Blood should have a pH of 7.35-7.45– If the pH of blood gets to high or too low, serious

complications can occur– A buffer system can help correct a pH imbalance• Does this by converting strong acids or bases into weak

acids or bases

Organic Compounds of the Body

• Organic compounds contain carbon

• Organized into various structures– Macromolecules – large

molecules– Polymers – built by putting

together repeating monomers

Organic Compounds in the Body

• In order to make a macromolecule– Dehydration synthesis must occur– Removing a water molecule, bind to monomers

together– XOH + YOH → XOY + H2O

• In order to break a macromolecule– Hydrolysis must occur– Adding a water molecule, break to monomers apart– XOY + H2O → XOH + YOH

4 Major Groups of Organic Compounds

• Carbohydrates• Lipids• Proteins• Nucleic Acids

Carbohydrates

• Include: sugars, glycogen, starches, cellulose• Examples in our diet– Bread, pasta, rice, cereal

• Function as a source of chemical energy (quick energy)• Made of carbon, hydrogen, and oxygen• 3 major groups– Monosaccharides– Disaccharides– polysaccharides

Carbohydrates

• Monosaccharides – one sugar (sweet)– Glucose, fructose, galactose

• Disaccharides – two sugars (sweet)– Sucrose, lactose, maltose

• Polysaccharides – many sugars (not sweet)– Glycogen, starch, cellulose

Lipids

• Include: triglycerides, phospholipids, steroids• Examples in our diet:– Fats, oils

• Function as a source of energy storage• Made of carbon, hydrogen, and oxygen• Are hydrophobic – do not dissolve in water• Lipids are made of repeating fatty acids

Lipids

• Triglycerides– Saturated fats – only single covalent bonds– Monounsaturated fats – one double bond– Polyunsaturated fats – more than one double bond

• Phospholipids– Important part of cell membrane

• Steroids– Important part of cell membrane, not all steroids are

anabolic

Proteins

• Include: proteins and enzymes• Examples in our diet:– Meat, fish, eggs, milk

• Function as catalysts, protect against invaders, hormones, cell transport, building blocks of body

• Made of carbon, hydrogen, oxygen, nitrogen, sulfur

• Proteins are made of repeating amino acids

Proteins• 20 different amino acids• Amino acids are joined by peptide bonds to

create polypeptide chains• Enzymes– Speed up chemical reactions within the body

Nucleic Acids

• Include: DNA and RNA• Examples in our diet:– none – but we eat the building blocks (amino

acids)• Function as inherited genetic material• Made of carbon, hydrogen, oxygen, nitrogen,

and phosphorous• Made of repeating chains of nucleotides

Nucleic Acids

• Nucleotides have 3 parts– Sugar– Phosphate– Nitrogenous base

ATP

• Adenosine triphosphate• ATP is not one of the 4 major groups of

organic molecules• ATP is essential to life – energy source