Enzyme and Energy Review
Enzyme
• Enzymes are catalytic molecules. That is, they speed
up specific reactions without being used up in the
reaction. Enzymes are proteins.
• All enzymes have three special features in common:
– 1. Enzymes do not create processes that would not take
place on their own. They just make the processes take
place faster!
– 2. Enzymes are not permanently altered or used up in
reactions.
– 3. Each enzyme catalyzes only one specific type of
reaction, but can catalyze many of this particular
reaction one after another.
Parts of an Enzyme
• Substrates are molecules that a specific enzyme can
chemically recognize and to which it can bind. Substrates
undergo chemical changes to form new substances called
products.
• Each substrate fits into an area of the enzyme called the
active site. It is like a lock-and-key mechanism. Once the
enzyme-substrate complex is together, the enzyme holds the
substrate in a position where the reaction can occur. Once the
reaction is complete, the enzyme unlocks the product and the
enzyme is free to facilitate another reaction.
Rate of the Reaction
• The rate of a reaction depends in part on the
concentration of the enzyme. If the enzyme is
diluted, its concentration is lowered, which
slows the reaction rate.
• Rate of reaction also depends on the amount
of energy present for the reaction to occur
• Temperature can also slow or speed up a
reaction.
Energy- The Big IDEA
• All life on Earth depends on the flow of energy. The primary
source of this energy is the Sun.
• Plants and other photosynthetic organisms (for example,
cyanobacteria, or bluegreen algae) are the entry point for this
flow of energy.
• The process of photosynthesis supports almost all life on
Earth directly or indirectly.
• Photosynthesis is the process that converts solar energy to
chemical energy in the form of carbohydrates.
• Carbohydrates are then broken down by the metabolism of
the cells of these photosynthetic organisms or by the cells of
other organisms, such as animals, fungi, or microbes that
consume plant materials.
• In all cells, the processes of life are constantly moving and
rearranging atoms, ions, and molecules. All this biological
work requires energy.
ATP- Stored Energy
• ATP, adenosine triphosphate, is a special molecule
that stores and releases the energy in its bonds in
response to the energy need of the cell.
• Cells work constantly to maintain a vast supply of
this energy storage molecule.
• The stored energy is released when ATP is split into
ADP, adenosine diphosphate, and an inorganic
phosphate.
Photosynthesis
• Occurs in autotrophs who use chlorophyll (pigment
found in cholorplast) to absorb sunlight.
• Must also have CO2 and H2O in order to work.
• 6CO2 + 6H2O + energy -> C6H12O6 + 6O2
• The goal is to change the sun’s energy into a usable
stored form of sugar.
Cellular Respiration
• Most all organisms have some sort of cellular respiration going on
inside their cells.
• Mitochondria convert sugar and O2 into usable energy, ATP.
• Two Main Reactions of Cellular Respiration:
– 1. Krebs Cycle – Breaks down the products of Glycolysis to produce
molecules used in the electron transport chain. 2 ATP
– 2. Electron Transport Chain – Consists of a series of proteins in the
mitochondrial membranes that convert ADP to ATP by transferring
electrons. 34 ATP