Chapter 7 Cellular Respiration

Slide 2: General Formulas

• Respiration:

  • C6H12O6 + 6O2 -> 6CO2 + 6H2O + energy

• Photosynthesis:

  • 6CO2 + 6H2O -> C6H12O6 + 6O2

Slide 3: Locations of Cellular Respiration

• Glycolysis: Occurs in the cytoplasm.

• Krebs Cycle: Takes place in the matrix of mitochondria.

• Electron Transport Chain (ETC) & ATPase: Located in the cristae of mitochondria.

  • Cristae is the folded inner membrane

Slides 4: Types of Respiration

• Anaerobic Respiration:

  • Has no O2 present; involves glycolysis in the cytoplasm as the first step and fermentation reactions in the 2nd step

• Aerobic Respiration:

  • Requires O2; includes glycolysis in the cytoplasm as the first step, imports into the mitochondria in the 2nd step, Krebs cycle in the 3rd, and electron transport (cristae) in the 4th.

Slide 5-7: Stages of Aerobic Respiration

• The purpose of aerobic respiration is to breakdown sugars and other food molecules to make ATP

  

1. Glycolysis - In cytoplasm

2. Import into Mitochondria (Transition Step)

3. Krebs Cycle (Citric Acid Cycle) - In the Matrix

4. Electron Transport Chain and ATP Synthesis

   

Slide 6: Electron Carrier

• Electrons are carried by NADH and FADH2.

• Phosphorylation Types:

  • Substrate-level phosphorylation

  • Oxidative phosphorylation

Slide 7: Glycolysis Breakdown

• Glycolysis:

  • Converts glucose into pyruvate, producing NADH and ATP.

• Krebs Cycle:

  • Produces CO2, ATP, NADH, and FADH2.

Page 8: Glycolysis Phases

• Energy Investment Phase:

  • 2 ATP used to convert glucose into fructose-1,6-bisphosphate.

• Energy Payoff Phase:

  • Produces 4 ATP and 2 NADH.

Slide 9: Parts of Glycolysis

• Part 1: Energy Investment Phase (steps 1-3); Cleavage and rearrangement (steps 4-5)

• Part 2: Energy Payoff Phase (steps 6-10)

Slide 10: Glycolysis Details

• Energy Investment:

  • Glucose (C6) + 2 ATP -> Fructose-1,6-bisphosphate (C6) + 2 ADP

• Cleavage & Rearrangement:

  • Fructose-1,6-bisphosphate (C6) -> 2 G3P (C3)

    • G3P: Glyceraldehyde-3-phosphate

Slide 11: Glycolysis Part 1

• Glucose C6 → DHAP C3 + G3C3 → 2 G3P C3

  • Energy input: 2 ATP

    • Start with C6 sugar

      • DHAP = Dihydroxyacetone

      • G3P = glyceraldehyde 3

        • Both sugars

Slide 12: Glycolysis Part 2

• Glyceraldehyde-3 phosphate (2x); After split in half 2x C3 sugars

• (G3P C3 → → → Pyruvate C3) x2

  • Part 2 energy output: 4 ATP + 2 NADH

Slide 13: Glycolysis Summary Part 1

• Substrate: Glucose (C6 sugar)

• Product (end of step 4): 2 C3 sugars (1 DHAP + 1 G3P)

Slide 14: Glycolysis Summary Part 2

• Substrate: 2 G3P (C3)

• Product: 2 pyruvate (C3 sugars)

Slide 15: Glycolysis Energy Yield

• Part 1 Energy Input: 2 ATP

• Part 2 Energy Output: 2 NADH + 4 ATP

• Net Energy Yield: 2 ATP + 2 NADH

Page 16: Glycolysis Overview

• Part 1: Energy In: 2 ATP

• Part 2: Energy Out: 4 ATP + 2 NADH

• Net Yield: 2 ATP + 2 NADH

Slide 19-21: Import into Mitochondria (Transition step)

• Pyruvate C3 + NAD+ + CoA -> Acetyl CoA + CO2 + NADH

• Net Energy Yield/Glucose: 2 NADH

• Coenzyme A

  • Acetyle CoA = acetyl (from pyruvate) attached to coenzyme A

Slide 22: Krebs Cycle Overview

• Input: 2 Acetyl CoA C2 + 2 Oxaloacetate C4 -> 2 Citric Acid C6+ 2 CoA

Slide 23: Krebs Cycle Reactions

• (1st reaction) Acetyl CoA C2 + Oxaloacetate C4 -> Citric Acid C6 +CoA

• Sugars are rearranged, decarboxylation → CO2 is relased

• Sugars are oxidized → Redox

  • Reduced, High energy compounds made NADH, FADH2

Slide 27: Energy Yield of Krebs Cycle

• Energy Per Cycle: 1 ATP, 1 FADH2, 3 NADH

• Energy Per Glucose: 2 ATP, 2 FADH2, 6 NADH

Slide 29: Net Energy Yield of Aerobic Respiration

• Total: 4 ATP + 10 NADH + 2 FADH2

  • All of the ATP made so far was made by substrate-level phosphorylation

Slide 31: Electron Transport Chain (ETC)

• Purpose: Uses energy from NADH and FADH2 to produce ATP by oxidative phosphorylayion = chemiosmosis

• Electron Transport: makes a H+ gradient

• oxidative phosphorylation: Creates a H+ gradient for ATP synthesis.

Slide 34: Electrons carriers are Arranged by Redox Potential in Cristae

• Electrons are passed down energy gradient in small increments

  • H+s are pumped across membrane

Slide: 38 Types of Electron Carries in the Electron Transport Chain

• Protein complexes in Cristae Membrane

  • Complex 1

  • Complex 2

  • Complex 3

  • Complex 4: Cytochrome c oxidase

• Mobile Electron Carries

  • Coenzyme Q/ Ubiquinone

    • Quinon = lipid

  • Cytochrome c = Small protein

Slide: 40:Electron Transport Generates a Proton Gradient

• As e-s are transported down the ETC, H+s are transported across the cristae membrane into the inter membrane space at 3 places:

  • Complex 1, complex 3 and complex 4

• The H+ gradient will be used as energy for ATP synthesis

Slide 41: ATP Synthesis

• ETC: Makes a H+ gradient = proton gradient

• ATP Synthase: Uses H+ gradient as a source of energy to make ATP

Slide 43: Pathway of Electron Transport

• When NADH donates e-s to the ETC the order of electron carries is:

  • NADH → 1 → CoQ → 3 → Cyto → 4 → O2

• When FADH2 donates e-s to the ETC the order of electron carries is:

  • FADH2 → 2 → CoQ → 3 → cyto → 4 → O2

• ETC: Electron transport chain

  • 1 FADH2/ 2ATP

Page 46: Consequences of Stopping Electron Transport

• Lack of O2 leads to no H+ gradient, halting ATP synthesis.

Slide 48: Poisons Stop Aerobic Respiration

• Many posions stop e- transport → no ATP synthesis Arsenic stops Krebs Cycle, inhibits part of Glycolysis

Slide 49: What happens if Electron Transport stops

• No H+ gradient is made → no energy to make ATP! ATP synthesis will stop

• Electron carries cant pass on their electrons, will all be stuck in reduced form

Slide 50: Krebs Cycle

• If no O2 all NAD+ will be in NADH form

• Cell will run out of NAD+/FAD+

• Any reactions that needs NAD+ or FAD+ will stop

Slide 51: Glycolysis Part 2

• If no O2 all NAD+ will be in NADH form

  • Any reaction that uses AND+ will stop Aerobic Respiration will stop

• Glycolysis will also stop unless there is another set of reactions to make NAD+ (Fermentation)

Slide 52: Electron Transport chain and Oxidative Phosphorylation

• Purpose: uses the energy in NADH and FADH2 To make ATP by Oxidative Phosphorylation = Chemiosmosis

• Electron Transport: makes a H+ gradient

• Oxidative Phosphorylation: uses the H+ gradient to make ATP

  • ATP synthase

Slide 53: Electron Transport and ATP Synthesis

• ETC: Makes a H+ gradient = proton gradient

• ATP Synthase: Uses H+ gradient as a source of energy to make ATP

Slide 57 : Energy Conversions

• Electrons from NADH

  • Pass through 3 proton pumping steps → A larger H+ Gradient is made → 3 ATP/NADH

• Electrons from FADH2:

  • Only pass through 2 proton pumping steps → Smaller gradient made → only 2 ATP / FADH2

Aerobic Respiration: Net Energy Yield per Glucose

Glycolysis: 2 ATP +(2*3=6ATP)

Import into Mt.: +(2*3=6ATP)

Krebs Cycle: 2 ATP +(6*3=18ATP)+ (2*2=4ATP)

Total= 4 ATP +30 ATP* +4 ATP* = 38 ATP

• 4 ATP by Substrate-level Phosphorylation = ( Enzyme reaction)

• 34 ATP by Oxidative Phosphorylation

• No free shipping! moving 2 NADH into mitochondria costs 1 ATP/NADH

  • 2 NADH made in cytoplasm move into mitochondria

    • Net gain in ATP: 38 ATP max - 2 ATP shipping = 36 ATP

Slide 62: Anaerobic Respiration Overview

• Process: Glycolysis followed by fermentation.

• Net Energy Gain: 2 ATP.

Slide 64: Alchohol Fermentation

• In plants fungi and some bacteria

  • Uses up 2 NADH! No ATP or O2 made!

Slide 65: Lactic Acid Fermentation

• In animals and some bacteria

Slide 66: Purpose of Fermentation

• Recycles NAD+ to allow glycolysis to continue.

  • Even if there is no energy gain cells carry out the fermentation reactions to regenerate the NAD+ so glycolysis can keep going

Slide 68: Anaerobic Respiration

• Glycolysis: Makes 2 ATP + 2 NADH

• Fermentation: 2 NADH → 2 NAD+

  • Recycles NAD+ so glycolysis can continue

• Even if there is no energy gain the cells carry out the fermentation reactions to regenerate the NAD+ so glycolysis can continue

Slide 70: Products of Fermentation

• Lactic Acid Fermentation: Produces lactate.

• Alcohol Fermentation: Produces ethanol and CO2.

Slide 71: Metabolism of Food Molecules

• Carbohydrates: Starch, disaccharides, sugars.

• Fats = Triglycerides:, glycerol, fatty acids.

• Proteins: Amino acids.

Slide 72: Food Digestion

• Carbohydrates starch → glucose C6 sugars → Enter at the beginning of glycolysis (Part 1 = C6 sugars)

• Disaccharides → C6 Sugars → Enter at beginning of Glycolysis (Part 1 = C6 sugars)

• Fats = Triglycerides → Glycerol C3 + 3Fatty Acids

• Glycerol C3 → G3P C3 Enter at the middle of glycolysis (Part 2 = C3 sugars)

• Fatty Acids C18 → Acetyl CoA C2 ×9 by beta oxidation Enter at 1st step of citric acid cycle (Krebs cycle)

Slide 76: Protein Metabolism

• Amino Acid C skeletons converted to sugars that can be broken down during Respiration

Slide 77-78: Key Reactions to Memorize

• Import into Mitochondria (Transition Step): Pyruvate (C3) + CoA + NAD+ -> Acetyl CoA (C2) + CO2 + NADH

• Krebs Cycle = Krebs Cycle: Acetyl CoA(C2) + Oxaloacetate(C4) -> Citric Acid (C6)+ CoA

• Fermentation: Animals

  • Pyruvate(C3) + NADH → LACTIC ACID (C3) + NAD+

• Fermentation: Plants, Fungi

  • Pyruvate (C3) → Acetaldehyde (C2) + CO2 Acetaldehyde (C2) + NADH → Ethanol (C2) + NAD+