Cellular Respiration Vocabulary:-Glycolysis -Kreb’s Cycle -Pyruvic acid -Fermentation -Aerobic Reaction -Anaerobic Reaction

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

After glucose is made in photosynthesis, how is the energy in the sugar molecules released so it can be used by the organism?After glucose is made in photosynthesis, how is the energy in the sugar molecules released so it can be used by the organism? –cellular respiration! Cellular Respiration occurs in both plant & animal cellsCellular Respiration occurs in both plant & animal cells –WHERE???? –CYTOPLASM & MITOCHONDRIA!!! The Power House of the Cell!!

Cellular Respiration… A Controlled Process Food (glucose), like fuel, is "burned" by our cells for energyFood (glucose), like fuel, is "burned" by our cells for energy –if it's burned all at once, too much energy is released therefore, the reaction is broken down into many small steps controlled by ENZYMEStherefore, 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 cellthe 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 groupsenergy is stored in bonds between phosphate groups AMP ADPATP P P

Cellular Respiration Process that releases ENERGY by breaking down food molecules in the presence of oxygenProcess that releases ENERGY by breaking down food molecules in the presence of oxygen Occurs in both plants and animalsOccurs in both plants and animals

Cell respiration occurs in 3 stages: GlycolysisGlycolysis Citric (Krebs) cycleCitric (Krebs) cycle Electron transport chainElectron transport chain

Glycolysis (glyco= sugar, lysis = breaks down) Process occurs in the cytoplasmProcess occurs in the cytoplasm Breaks glucose down from 6-carbon compound into two 3-carbon compounds (called pyruvate)Breaks glucose down from 6-carbon compound into two 3-carbon compounds (called pyruvate)Equation: enzymes in enzymes in C 6 H 12 O 6 2 pyruvates + 2 ATP cytoplasm cytoplasm

Glycolysis can occur if oxygen is present (aerobic) or absent (anaerobic)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 Respiration/KrebsIf oxygen IS present, then cells proceed with Respiration/Krebs If oxygen is NOT present, then cells fermentIf oxygen is NOT present, then cells ferment

Cellular Respiration can be broken down into 2 processes: 1)Glycolysis: breaking down glucose 2)Respiration (Krebs Cycle & Electron Transport Chain): uses oxygen to finish breaking down products from Glycolysis & release energy

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???

Respiration/Krebs Occurs in the Mitochondria of cellOccurs in the Mitochondria of cell Only if oxygen is PRESENT (aerobic)Only if oxygen is PRESENT (aerobic) Uses the pyruvic acid from glycolysis to produce carbon dioxide, water, and ATPUses the pyruvic acid from glycolysis to produce carbon dioxide, water, and ATP Products:Products: –34 ATP per molecule of glucose – carbon dioxide –water

So how does this happen? The Citric (Krebs) cycle and the electron transport chain turn the pyruvate into CO 2, H 2 O, and ATPThe Citric (Krebs) cycle and the electron transport chain turn the pyruvate into CO 2, H 2 O, and ATP To do this, pyurvate loses a carbon atom to make Acetyl CoATo do this, pyurvate loses a carbon atom to make Acetyl CoA

Acetyl CoA enters the Krebs Cycle to produce CO 2, NADH, and FADH 2Acetyl CoA enters the Krebs Cycle to produce CO 2, NADH, and FADH 2 The NADH and FADH 2 carry energy to the electron transport chain to make more ATP (this requires oxygen)The NADH and FADH 2 carry energy to the electron transport chain to make more ATP (this requires oxygen) C 6 H 12 O 6 + 6O 2 6 CO H 2 O + 36 ATP

Summary of Cellular Respiration GLYCOLYSIS “break sweetness” RESPIRATION/ Kreb’s Cycle Location in the cell: CytoplasmMitochondria It starts with: C 6 H 12 O 6 (glucose) 2 pyruvic acid It ends with: 2 (C 3 H 6 O 3 ) pyruvic acid H 2 O, CO 2, ATP Is Oxygen required? NO YES!  AEROBIC # of ATP’s Produced: 2 (tiny) 34 (lots!)

GRAND TOTAL= 36 ATP!! 2 are produced in Glycolysis and 34 in Respiration/ Kreb’s Cycle2 are produced in Glycolysis and 34 in Respiration/ Kreb’s Cycle –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 38% of the total energy in glucoseThe 36 ATP molecules the cell makes per 1 glucose represents about 38% of the total energy in glucose Even though it doesn’t seem like much, this is more efficient than your car’s gas burning engineEven though it doesn’t seem like much, this is more efficient than your car’s gas burning engine What happens to the remaining 62%???What happens to the remaining 62%??? –It is released as heat.

What happens if your cells aren’t getting enough oxygen? Respiration/Kreb’s CANNOT proceedRespiration/Kreb’s CANNOT proceed Fermentation occursFermentation occurs –Pyruvic Acid builds up in animal muscle cells as LACTIC ACID… feel the burn! –In other organisms, the pyruvic acid builds up, ferments, and becomes alcohol

Fermentation: release of energy from food molecules in absence of oxygen (anaerobic)Fermentation: release of energy from food molecules in absence of oxygen (anaerobic) Enables cells to carry out energy production in the absence of OxygenEnables cells to carry out energy production in the absence of Oxygen result of glycolysis + fermentation yields 2 ATP molecules per 1 molecule of glucose (not nearly as much energy!!!!)result of glycolysis + fermentation yields 2 ATP molecules per 1 molecule of glucose (not nearly as much energy!!!!)

2 Fermentation Pathways: 1.Lactic Acid Fermentation: pyruvic acid from glycolysis is converted to lactic acidpyruvic acid from glycolysis is converted to lactic acid lactic acid is produced in muscles during rapid exercise (body can't supply enough O 2 to the tissues)lactic acid is produced in muscles during rapid exercise (body can't supply enough O 2 to the tissues) the build-up of lactic acid causes a burning, painful sensation in your musclesthe build-up of lactic acid causes a burning, painful sensation in your muscles

Energy & Exercise: Quick Energy Muscle cells only contain enough ATP for a few seconds of “burst” energyMuscle cells only contain enough ATP for a few seconds of “burst” energy –emergency, starting gun of race When this is gone, cells resort to lactic acid fermentation which can provide enough ATP for about 90 secondsWhen this is gone, cells resort to lactic acid fermentation which can provide enough ATP for about 90 seconds

Long Term Energy If a race or energy need is longer, your body must go through cellular respiration to get enough ATP to continueIf a race or energy need is longer, your body must go through cellular respiration to get enough ATP to continue –Even well-conditioned athletes have to pace themselves –Your body stores energy in muscle glycogenglycogen –these stores are enough to last for minutes of activity when broken down through cellular respiration –After this, your body begins to break down fats and other stored molecules

2.Alcoholic Fermentation: Occurs in yeast cells & some other microorganismsOccurs in yeast cells & some other microorganisms Pyruvic acid is broken down into a 2-Carbon alcohol plus carbon dioxidePyruvic acid is broken down into a 2-Carbon alcohol plus carbon dioxide

Alcoholic Fermentation Important to brewers & bakers!Important to brewers & bakers! –When yeast in dough runs out of oxygen it ferments, giving off bubbles of carbon dioxide gas—which forms air space in bread –Alcohol produced in the dough evaporates when bread is baked *(when the level of alcohol reaches 12%, yeast cells die)