Ch. 2
Part 2
The Chemical Level of Organization
Inorganic vs. Organic
• Inorganic
– Usually lack carbon
– Structurally simple
– Include:
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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
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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
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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