CELLS @ WORKCELLS @ WORK

Cell Metabolism and ATPCell Metabolism and ATP• ATP is the energy molecule

of the cell.• Billions are used and

reassembled every second!!• Endergonic Rxn – Requires

energy (ie. Photosynthesis)

• Exgergonic Rxn – releases energy

(ie.Cellular Respiration)• Glucose = 1 dollar• ATP = 1 penny

EnzymesEnzymesOur “Key” to Biochemical

Reactions

ENZYMESENZYMES

• Proteins that accelerate chemical reactions

• Almost all processes in the cell need enzymes in order to occur – Cellular Respiration, Photosynthesis, food digestion etc.

• Are extremely selective – very specific to certain reactions

ENZYMESENZYMES

• For Example:For Example:

Lysozyme digests bacterial cell walls, and is found in human tears, egg-white, etc

ENZYMESENZYMES

• Enzymes are known to catalyze about 4,000 reactions in the human body

• Named according to the reaction they catalyze … “ase” is added to the name of the substrate

• Ex: Lactase breaks down lactose

HOW ENZYMES WORK:HOW ENZYMES WORK:

• By providing a lower activation energy for a reaction and dramatically accelerating its rate

• For example… (Do not copy)– the reaction catalysed by orotidine-

phosphate decarboxylase will consume half of its substrate in 78 million years if no enzyme is present. However, when the decarboxylase is added, the same process takes just 25 milliseconds

HOW ENZYMES WORK:HOW ENZYMES WORK:

EnzymeEnzymeSUBSTRATE PRODUCT(S)

Eg:Eg:

SucraseSucraseSucrose + Water Glucose + Fructose

Enzymes help a reaction to occur … without being directly involved!!!

HOW ENZYMES WORK:HOW ENZYMES WORK:

• ““Lock and Key” Model:Lock and Key” Model:

HOW ENZYMES WORK:HOW ENZYMES WORK:

Competitive InhibitorsCompetitive Inhibitors

• A molecule similar in shape to the substrate bonds with the enzyme’s active site and inhibit its function.

• Poisons: cyanide and arsenic bind to key enzymes in this manner…death may result!

F.Y.I:F.Y.I:

• Carbohydrases break down________

• Proteases break down… ________

• Lipases break down…________

ENZYMESENZYMES• Work at optimal temp. & pH

• If it is too hot, an enzyme can become DENATURED… and will no longer function properly

The End!!!The End!!!