Vocabulary: -Glycolysis-ATP -Krebs Cycle -electron transport chain -Pyruvic acid -glucose -Aerobic / Anaerobic NOTES: Cellular Respiration

Review What is photosynthesis? Where does this occur? What is the difference between ATP and ADP? What is the difference between NADPH and NADP + ? Light dependent vs. Light independent reactions

Chemical Energy & Food Organisms get the energy they need from FOOD. Energy stored in food is expressed in units of CALORIES. 1 calorie = the amt. of energy needed to raise the temp. of 1 g of H 2 O by 1°C.

Chemical Energy & Food Different foods are capable of storing different amounts of energy: 1 g glucose: 3811 calories (3.811 kcal) 1 g beef fat: 8893 calories (8.893 kcal)

How is the energy in sugar (glucose) molecules released so it can be used by the cells of an organism?  cellular respiration! Cellular Respiration occurs in both plant & animal cells  WHERE????  CYTOPLASM & MITOCHONDRIA!!! The POWERHOUSE of the Cell!!

Cellular Respiration… A Controlled Process Food (glucose), like fuel, is "burned" by our cells for energy  however, if it's burned all at once, too much energy is released therefore, the reaction is broken down into many small steps controlled by ENZYMES  Cells gradually release the energy from glucose and other compounds

the energy is transferred to the bonds of ATP which stores and releases the energy in usable amounts to be used by the cell energy is stored in bonds between phosphate groups AMP ADPATP P P

Cellular Respiration: A process that releases ENERGY by breaking down food molecules in the presence of OXYGEN Occurs in both plants and animals

Cell respiration occurs in 3 stages: Glycolysis Krebs cycle Electron transport chain “RESPIRATION” (uses oxygen)

GLYCOLYSIS (glyco= sugar, lysis = breaks down) Process occurs in the cytoplasm Breaks glucose down from 6-carbon compound into two 3-carbon compounds (called PYRUVATE or PYRUVIC ACID) Equation for glycolysis: enzymes in C 6 H 12 O 6 2 pyruvates + 2 ATP cytoplasm

Glycolysis can occur if oxygen is present (aerobic) or absent (anaerobic)  Glycolysis is ALWAYS the first step in breaking down glucose If oxygen IS present, then cells proceed with Krebs cycle & electron transport chain If oxygen is NOT present, then cells will carry out fermentation

Cellular Respiration can be broken down into 3 processes: 1) Glycolysis: glucose is broken into 2 pyruvate; 2 ATPs produced; electrons from glucose passed to NAD +  NADH 2) Krebs Cycle: pyruvate broken down into CO 2 (waste) & electrons are passed to NAD +  NADH; 2 ATPs produced 3) Electron Transport Chain: high energy elec. from glycolysis & Krebs (NADH) are used to convert ADP  ATP; oxygen must be present

GLUCOSE O2O2 CO 2 H 2 O & heat energy Glucose + Oxygen Carbon Dioxide + Water C 6 H 12 O 6 + 6O 2 6CO 2 + 6H 2 O Look familiar???

Krebs Cycle & E.T.C. Occur in the MITOCHONDRIA of a cell Only if oxygen is PRESENT (aerobic) Use the pyruvic acid from glycolysis to produce carbon dioxide, water, and ATP Products:  34 ATP per molecule of glucose  carbon dioxide  water

So how does this happen? The KREBS CYCLE breaks the bonds of pyruvate; high-energy electrons are passed to NAD +  NADH; waste product CO 2 produced; 2 ATPs produced. ELECTRON TRANSPORT CHAIN: uses high-energy electrons from NADH (&FADH 2 ) from gly. & Krebs to convert ADP  ATP

The NADH and FADH 2 (from glycolysis & Krebs cycle) carry energy to the electron transport chain to make more ATP (this requires oxygen; oxygen acts as the final electron acceptor in the chain) Equation for Respiration: C 6 H 12 O 6 + 6O 2 6CO H 2 O + 36 ATP

Summary of Cellular Respiration GLYCOLYSIS “break sugar” Krebs Cycle & E.T.C. Location in the cell: CytoplasmMitochondria It starts with: C 6 H 12 O 6 (glucose) 2 pyruvic acid O 2 It ends with: 2 (C 3 H 6 O 3 ) pyruvic acid H 2 O, CO 2, ATP Is Oxygen required? NO (ANAEROBIC) YES! (AEROBIC) # of ATP’s Produced: 2 (tiny)34 (lots!)

GRAND TOTAL = 36 ATP!! 2 are produced in Glycolysis, 2 in Krebs Cycle, and 32 in Elec. Trans. Chain  18 times more ATP are produced in the presence of Oxygen!!

How efficient is this?? The 36 ATP molecules the cell makes per 1 glucose represents about 36% of the total energy in glucose Even though it doesn’t seem like much, this is more efficient than your car’s gas burning engine What happens to the remaining 64%???  It is released as heat.