Lesson Overview Lesson Overview Cellular Respiration: An Overview What do you know about respiration?

Lesson Overview Cellular Respiration: An Overview

What do you know about respiration?


Where do heterotrophs get energy?• Autotrophs vs. heterotrophs• Chemical energy• Calories– 1Cal = 1000 cal– Carbs/proteins 4Cal/g– Fats 9 Cal/g

• Cells– Don’t burn food– Break down gradually– Produce ATP


Respiration Overview• Oxygen + glucose carbon dioxide + water + energy

6O2 + C6H12O6 6CO2 + 6H2O + energy• Several steps– Slow release of energy– Useful forms of energy

• Glycolysis– Glucose into pyruvic

acid– Produces ATP– Cytoplasm


• Krebs cycle– Produces ATP– Releases CO2

– Mitochondria• Electron transport chain– Uses products of

Krebs cycle and glycolysis

– Oxygen into water– Mitochondria


Oxygen’s Importance• Breathing = respiration• Aerobic– Electron transport

chain–Krebs cycle

• Anaerobic–Glycolysis– Fermentation


Respiration vs. Photosynthesis

• Reverse of each other– True globally

• Use respiration–Nearly all forms

• Use photosynthesis–Plants, bacteria, algae

• Photosynthesis deposits energy, respiration withdraws it


How did you get to school today? How is that similar to

respiration?


Glycolysis• 1st step– Uses glucose and 2 ATP– Makes two 3-carbon

molecules• 2nd step: makes– Two pyruvic acid molecules– 4 ATP– 2 NADH

• Overall– Reactants– Products– Anaerobic– Occurs quickly


Krebs Cycle• Matrix of mitochondria• Pyruvic acid– 2 steps– Produces NADH, CO2

– Creates acetic acid• Acetic acid– Reacts with coenzyme A– Forms acetyl-CoA

• Acetyl-CoA– Joins 4-carbon compound– Forms citric acid


Citric Acid

• Cycle• 5-carbon• 4-carbon• Releases 2 CO2

• Creates 3 NADH, FADH2

• ATP indirectly• 4-carbon continues cycle• 2 turns per glucose• So, 1 glucose =



Electron Transport Chain• Where?– Inner membrane of mitochondria–Cell membrane

• NADH and FADH2

–Passed through proteins–Pump H+ into intermembrane space–Concentration gradient– Low energy electrons join oxygen water



Chemiosmosis• Same as photosynthesis• ATP synthase– In inner mitochondrial

membrane–Uses concentration

gradient–Releases ATP in matrix

• 2 electrons 3 ATP


Respiration Total• 1 glucose =– 36 ATP– 6 CO2

– 10 NADH– 2 FADH2

• 18x more energy when aerobic

• 36% efficient• Can be used with more

complex molecules– First broken down


Fermentation• Anaerobic• Cytoplasm• Alcoholic fermentation– Yeasts,

microorganisms– Pyruvic acid + NADH

alcohol + CO2 + NAD+

– NAD+ reused– Alcoholic beverages– Bread


Lactic Acid Fermentation• Major pathway• Pyruvic acid + NADH lactic acid + NAD+

• NAD+ reused• Creates cheese,

yogurt, sour cream, pickles, sauerkraut

• Exercise “burn” in muscles– Removed with

enough oxygen


Energy Use• Short bursts of energy–ATP in muscles–Lactic acid fermentation

• Longer than 90 sec. of energy–Respiration only method–15-20 min stored in glycogen in

muscles–Break down other stored molecules

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Lesson Overview Lesson Overview Cellular Respiration: An Overview What do you know about respiration?