Physiology Ch.4

• Most enzymes are proteins
• Have specific shapes, so they don't have the same shape
• Named according to their job/activity
• Can be measured in a clinical laboratory to look for disease
• Functionally are biological catalysts

• Chemicals that increase the rate of reaction
• Are not changed at the end of the reaction (structure not changed)
• Do not change the nature of the reaction or final result
• Lower the activation enery required

• Substrates have specific shapes (3-dimensional) to fit into the active sites (lock and key model)
• Substrate fits into active sites in enzyme
• ----all happening inside the cell

• Concentration of the enzyme in the solution
• Temperature of the solution in which the reaction is occuring
• Ph of the solutiion in which the reaction is occuring
• Concentration of coenzymes/cofactors (helpers) in the solution (helps enzymes to be more efficient

• Rate of reaction increases as temperature increases from 0 C up to 37 C
• Reaction rate plateaus, slightly above body temperature (37 C)
• Above 37 C reaction rate decreases as the temperature continues to increase

From 0 C reaction rate is very slow, it progressively increases as the temperature increases but them plateaus at 37 C (body temp) and then decreases again as the temperature continues to increase

• Each enzyme exhibits peak activity at narrow pH range (pH optimun)
• pH optimum reflects the pH of the body fluid in which the enzyme is found
• If pH changed, so is no longer within the enzyme range; reaction will decrease

Each enzyme has a pH optimun and an increase or decrease in pH can slow down the reaction time

• Enzymes may be produced in an inactive form
• Phosphorlation/dephosphorylation (Activation/inactivation of an enzyme)

• Sequence of enzymatic reactions that begins with initial substrate, progesses through intermediates and ends with a final product (like an assembly line)
• Thousands of enzymatic reaction within a cell do not occur independently of one another-instead they are all connected and effect one another (like branches on a tree)