Cellular Cellular RespirationRespiration

How do living things get How do living things get the the energyenergy they need to survive? they need to survive?

From the food they From the food they eat!eat!

Remember the Remember the gummy bear?!?gummy bear?!?

Chemical Energy and FoodChemical Energy and FoodOne gram of One gram of glucoseglucose (C(C66HH1212OO66), when burned in the ), when burned in the presence of Opresence of O22, releases , releases 38113811 caloriescalories of heat E. of heat E. A A caloriecalorie is a measure of is a measure of energy.energy.In respiration, Cells release the In respiration, Cells release the energy from glucose, which is energy from glucose, which is stored in stored in chemical bondschemical bonds, , beginning with beginning with GLYCOLYSISGLYCOLYSIS! !

Overview of Cellular RespirationOverview of Cellular Respiration

Cellular respiration is the process that releases Cellular respiration is the process that releases energy by breaking down glucose and other energy by breaking down glucose and other food molecules in the presence of oxygen. food molecules in the presence of oxygen.

Equation:Equation:

6O6O22 + C + C66HH1212OO66 → 6CO→ 6CO22 + 6H + 6H22O + energyO + energy

oxygen + glucose → carbon dioxide + water + energyoxygen + glucose → carbon dioxide + water + energy

MEMORIZE THIS! MEMORIZE THIS!

(Psst - Look familiar?!)(Psst - Look familiar?!)

YES!YES!The equation for cellular The equation for cellular respirationrespiration is the is the exact exact opposite opposite of that of of that of photosynthesis!photosynthesis!

Photosynthesis:Photosynthesis:

6CO6CO22 + 6H + 6H22O + energy → O + energy → 6O6O22 + C + C66HH1212OO66

Respiration:Respiration:

6O6O22 + C + C66HH1212OO66 → 6CO→ 6CO22 + 6H + 6H22O + energyO + energy

Photosynthesis and Respiration make a cycle Photosynthesis and Respiration make a cycle called the Carbon cycle. called the Carbon cycle.

Overview of Cellular RespirationOverview of Cellular Respiration

Overview of Cellular RespirationOverview of Cellular Respiration

Two main stages:Two main stages:

1. glycolysis 1. glycolysis (in the cytoplasm)(in the cytoplasm)

2. Aerobic Respiration 2. Aerobic Respiration (in the mitochondria)(in the mitochondria)

The First Step: GlycolysisThe First Step: GlycolysisGlycolysis is the process in which Glycolysis is the process in which one molecule of glucose is broken in one molecule of glucose is broken in half, producing two molecules of ATPhalf, producing two molecules of ATP

The First Step: GlycolysisThe First Step: Glycolysiscells have to cells have to put in (use) put in (use) 2 2 ATP’s to ATP’s to get glycolysis started, but get glycolysis started, but 4 4 ATP’s ATP’s are are producedproduced at the end of at the end of glycolysis, for a net glycolysis, for a net gaingain of of 2 2 ATP’s ATP’s

The First Step: GlycolysisThe First Step: Glycolysisthis process is so fast that thousands this process is so fast that thousands of ATPs can be produced in a few of ATPs can be produced in a few milliseconds! milliseconds!

Glycolysis does NOT require oxygen! Glycolysis does NOT require oxygen!

The First Step: GlycolysisThe First Step: GlycolysisATP goes off to the other ATP goes off to the other parts of the cell to do workparts of the cell to do work

The other products of The other products of glycolysis are sent off to the glycolysis are sent off to the mitochondria to be further mitochondria to be further broken down to produce broken down to produce much moremuch more energy rich ATP! energy rich ATP!

What if oxygen is NOT present?What if oxygen is NOT present?if there is no oxygen present, if there is no oxygen present, glycolysis is followed by another glycolysis is followed by another pathway, Anaerobic Fermentation. pathway, Anaerobic Fermentation. (Anareobic means “no air”)(Anareobic means “no air”)

Two types of fermentationTwo types of fermentation

1. Alcoholic Fermentation1. Alcoholic Fermentation

2. Lactic Acid Fermentation2. Lactic Acid Fermentation

Alcoholic FermentationAlcoholic Fermentation

used by yeasts (& other microorganisms)used by yeasts (& other microorganisms)

equation:equation:

pyruvic acid + NADH pyruvic acid + NADH alcohol + CO alcohol + CO22 + NAD + NAD++

Creates CO2 and alcoholCreates CO2 and alcohol

Lactic Acid FermentationLactic Acid Fermentation

equation:equation:

pyruvic acid + NADH pyruvic acid + NADH lactic acid + NADlactic acid + NAD++

LAF is a back up fermentation for your cells when LAF is a back up fermentation for your cells when they don’t get enough Oxygen. This is why your they don’t get enough Oxygen. This is why your muscles burn when you work out. muscles burn when you work out.

lactic acid is also a waste lactic acid is also a waste product for some organisms product for some organisms to make food and beverages to make food and beverages such as cheese, yogurt, such as cheese, yogurt, buttermilk, and sour creambuttermilk, and sour cream

What if there is Oxygen?…What if there is Oxygen?…

If there IS oxygen present, Aerobic If there IS oxygen present, Aerobic Respiration follows Glycolysis. Respiration follows Glycolysis.

The Krebs CycleThe Krebs Cycle

The second part of respiration occurs in the The second part of respiration occurs in the mitochondriamitochondria

It can produce a LOT more ATP than glycolysis.It can produce a LOT more ATP than glycolysis.

The TotalsThe TotalsGlycolysis Glycolysis only produces only produces 2 ATP2 ATP molecules per one molecules per one glucoseglucose

With With OO22, glycolysis and , glycolysis and Aerobic Respiration Aerobic Respiration produce produce 36 ATP36 ATP molecules per one molecules per one glucose!glucose!

Energy and ExerciseEnergy and Exercise

At the start of a race, your body has At the start of a race, your body has access to access to 3 ATP sources3 ATP sources::

1. 1. stored ATPstored ATP already in muscles already in muscles

2. 2. new ATPnew ATP made by made by lactic acid lactic acid fermentationfermentation

3. 3. new ATPnew ATP made by made by cellular respiration cellular respiration

Energy and Exercise: Energy and Exercise: Quick EnergyQuick Energy

stored ATPstored ATP can provide E can provide E for a few seconds for a few seconds (50 meters) (50 meters)

new ATPnew ATP made by made by lactic lactic acid fermentationacid fermentation provides provides energy for about 90 sec energy for about 90 sec (200-300 meters)(200-300 meters)

lactic acid fermentation produces lactic acid, lactic acid fermentation produces lactic acid, which can only be rid of with extra oxygen – which can only be rid of with extra oxygen – where does this come from? heavy breathing where does this come from? heavy breathing after the race!after the race!

Energy and Exercise: Energy and Exercise: Long-Term EnergyLong-Term Energyyour body uses your body uses ATP from ATP from cellular respirationcellular respiration for for endurance racesendurance races

cellular respiration releases cellular respiration releases energy more slowly than energy more slowly than fermentation, which is why fermentation, which is why athletes have to pace athletes have to pace themselvesthemselves

after 15-20 min of activity, your after 15-20 min of activity, your body uses energy from other body uses energy from other stored molecules (such as fats) stored molecules (such as fats) for energy, which is why aerobic for energy, which is why aerobic forms of exercise are good for forms of exercise are good for weight lossweight loss

Comparing Photosynthesis & Cellular RespirationComparing Photosynthesis & Cellular Respiration

energy energy

Photosynthesis Cellular Respiration

function energy capture energy releases

location chloroplasts mitochondria

reactants CO2 and H2O C6H12O6 and O2

products C6H12O6 and O2 CO2 and H2O

equation

6CO2 + 6H2O → C6H12O6 + 6O2 C6H12O6 + 6O2 → 6CO2 + 6H2O