Resp Slides

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Cellular Respiration

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From Sugar to ATP

v  So plants take energy from the sun and store it in

sugars.

v  Plants (and all other living things) have to transfer that

stored energy into ATP.

v  This happens in ANOTHER organelle! Remember

the mitochondria?? Now you know why people call it the “powerhouse” of the cell.

v  Your mitochondria (and its

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Endosymbiotic

Theory

v  Mitochondria and Chloroplasts

look very much like prokaryotes INSIDE eukaryotic cells

v  Have 2 membranes

v  Own DNA

v  Can transfer energy

v  This theory attempts to explain

how multicellular organisms arose from single cellular

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Cellular Respiration

v  Process that releases energy from food in the presence

of oxygen.

v  Cellular respiration converts the energy stored in the

bonds of glucose into ATP

v  The byproducts are carbon dioxide and water

v  glucose + O₂ —> ATP + H₂O + CO₂

Glucose Oxygen gas Carbon

dioxide

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Cellular Respiration:

Three Steps

v  For each glucose molecule that

enters cellular respiration, ~36 ATP molecules are produced

v  Most are produced by the

electron transport chain

v  Each step includes numerous

reactions controlled by specific enzymes

v  NADH and FADH₂ carry

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Step 1:

Glycolysis

v  This step does not require

oxygen and is common to all cells (even anaerobic bacteria)

v  Evolutionarily, this was

probably the first mechanism for transferring energy from food to ATP.

v  Occurs in Cytoplasm

v  Glucose begins to be broken

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Step 2:

The Krebs Cycle

v  Glycolysis released 25% of the

energy available from Glucose

v  Krebs Cycle A.K.A. Citric

Acid Cycle or TCA releases more

v  Occurs in the mitochondria

v  Some of the glucose’s carbons

are released as carbon dioxides

v  This step is why you breathe out

CO₂!

Glucose Glycolysis

Krebs Cycle on Transport

o o

lectroro

Elec

CO2

Energy Energy

O2 H2O

Energy NADH NADH NADH NAD+ NAD+ NAD+ FAD NADH NAD+ ATP ATP CoA CoA ADP ADP FADH2 Pyruvic Acid

To Electron Transport Chain To Electron Transport Chain

MATRIX

CYTOPLASM

Citric Acid Production Pyruvic acid from glycolysis reacts to form acetyl-CoA, which then enters the Krebs cycle. In the process, a molecule of CO2

is produced and 2 high-energy electrons are passed to NAD+_to

produce NADH. Acetyl-CoA combines with a 4-carbon compound in the Krebs cycle to produce citric acid.

Energy Extraction Through a series of many reactions, citric acid is broken down into a 5-carbon compound, and then a 4-carbon compound (releasing 2 CO2 molecules along

the way). This 4-carbon compound can then start the cycle over again by combining with acetyl-CoA. Energy released by the breaking and rearranging of carbon bonds is captured in the forms of ATP, NADH, and FADH2.

CO2 CO2 CO2 Citric Acid Inner mitochondrial membrane Acetyl-CoA Outer mitochondrial membrane

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Step 3:

Electron Transport

Chain

v  Occurs in the mitochondria.

v  H+ gradient is used to make

ATP with ATP synthase (just like the light reactions)

v  Oxygen is required. This step

is why you have to breathe!

v  The hydrogens and “spent”

electrons make H₂O

v  Without O₂, the H+ would

build up and ATP synthase would not function and you would have no ATP

4H+ _O

2 4e- 2 H2O

+ + NADH NADH NADH NAD+ ATP ATP ADP ADP FAD FADH2 FADH2 H+ H+ H+ H+ H+ H+ H+ H+ From Glycolysis From Krebs Cycle MATRIX INTERMEMBRANE SPACE Inner mitochondrial membrane Electron carriers Outer mitochondrial membrane ATP Production

H+_{ions pass back across the}

mitochondrial membrane through ATP synthase causing the base of the synthase molecule to rotate. With each rotation, driven by the move-ment of an H+_{ion, ATP synthase}

generates ATP from ADP.

Electron Transport

High-energy electrons from NADH and FADH2 are passed from

carrier to carrier, down the electron transport chain. Water is formed when oxygen accepts the electrons in combination with hydrogen ions. Energy generated by the electron transport chain is used to move H+_{ions across the}

inner mitochondrial membrane and into the intermembrane space.

CYTOPLASM F Glucose Glycolysis Krebs Cycle Electron Transport CO2 Energy Energy Energy

O2 H2O

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117 Lesson 9.2 9.2 The Electron Transport Chain

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Cell Respiration Reactants

and Products

Sugar + O₂

H₂O

è ATP

Sugar

Eating

H₂O

è ATP

Autotrophs

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A Cycle of Life

v  Nearly all the chemical energy

that organisms use comes

ultimately from sunlight and is stored as sugar

v  Autotrophs can make their own

sugar and then convert it to ATP

v  But, Heterotrophs must get this

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Quiz 3/13

1.  During which of the three steps of cellular respiration is O₂ used?

2.  During which of the three steps of cellular respiration is CO₂

produced?

3.  What two products of photosynthesis are required for cellular

respiration?

4.  What two products of cellular respiration are required for

photosynthesis?

5.  T/F Plants do not have mitochondria.

6.  What part of the chloroplast does light enter? (Thylakoid or Stroma)

7.  Carbon comes into our bodies as a (solid/gas).

8.  Carbon leaves our bodies as a (solid/gas).

9.  How many phosphates are in ATP?

10.  T/F ATP is a form of chemical energy.

11.  BONUS: What is the name of the enzyme that makes ATP and is