BIO210 – Chapter 2: The Chemical Level of
• Activation Energy: is the amount of energy needed to start a rxn.
• Enzymes: promote chemical rxns by lowering the activation energy requirements
• Catalysts: compounds that accelerate the rate of chemical rxns w/o being consumed/ changed during the rxn
• Exergonic (Exothermic) Produce more energy than they use
• Endergonic(Endothermic) Use more energy than they produce
• Acidic pH:
o Lower Than 7.0
o High H+ concentration
o Low OH− concentration
• Basic (or alkaline) pH Higher Than 7.0
o Low H+ concentration
o High OH− concentration
• pH of Human Blood
o Ranges from 7.35 to 7.45
• Organic Molecules
o Contain H, C, and usually O
o Are covalently bonded
o Contain functional groups that determine chemistry
Proteins (or amino acids)
o Contain carbon, hydrogen, and oxygen in a 1:2:1 ratio
o Monosaccharide — simple sugar
o Disaccharide — two sugars
o Polysaccharide — many sugars
o Simple sugars with 3 to 7 carbon atoms
o Glucose, fructose, galactose
o Two simple sugars condensed by dehydration synthesis
o Sucrose,maltose • Polysaccharides
o Many monosaccharides condensed by dehydration synthesis
o Glycogen, starch, cellulose
• Eicosanoids: are lips derived from arachidonic acid, a fatty acid that must be absorbed in the diet b/c it cannot be
synthesized by the body. There are two major classes:
o Leukotrienes : produced mostly by cells involved w. coordinating the responses to injury or disease.
o Prostaglandins: are shortchain fatty acids in which five of the carbon atoms are joined in a ring. These
compounds are released by cells to coordinate or direct local cellular activities and they are extremely
powerful even in small quantities.
prostaglandins from damaged tissues stimulate nerve endings that produce the sensation of pain
• glycolipids: Compounds created by the combination of carbohydrate and lipid components.
• Proteins are formed from amino acids and contain carbon, hydrogen, oxygen and nitrogen
• Proteins perform a variety of essential functions, which can be classifies into seven major categories:
1. Support: Structural proteins create 3D framework for the body, providing strength, organization, and support
for cells, tissues, and organs.
2. Movement: Contractile proteins are responsible for muscular contraction; related proteins are responsible for
the movement of individual cells.
3. Transport: Some things can’t be transferred through the blood unless they are bound to transport proteins.
4. Buffering: provide buffering action and thereby help prevent dangerous changes in cellular and tissue pH.
5. Metabolic Regulation: Enzymes accelerate chemical reactions in cells, control the pace and direction of
6. Coordination and Control: protein hormones can influence the metabolic activities of every cell in the body or
affect the function of specific organs & systems
7. Defense: waterproof proteins such as skin, nails and hair protect the body from environmental hazards
• Proteins consist of long chains of organic molecules called amino acids, each amino acid consists five components:
o a central carbon atom
o a hydrogen atom
o an amino group (NH 2
o a carboxyl group (COOH) which can release a hydrogen ion to form a carboxyl ion
o an R group
• peptide: A chain of amino acids linked by peptide bonds.
• peptide bond: A covalent bond between the amino group of one amino acid and the carboxyl group of another.
• polypeptide: A chain of amino acids strung together by peptide bonds; those containing more than 100 peptides are called proteins.
• Proteins have four levels of structural complexity:
o Primary Structure: is the sequence of the amino acids along the length of a single polypeptide
o Secondary Structure: results from the bonds b/w atoms at different parts of the polypeptide chain. Hydrogen
bonding alphahelix or ßpleated sheets, the form depends on the sequence of amino acids and where the h
bonding occurs along the chain.
o Tertiary Structure: is the complex coiling and folding that gives a protein its final 3D shape, result from
interactions b/w the polypeptide chain and the surrounding water molecules and b/w the R groups of amino
acids in different parts of the molecule.