Overview cellular respiration cells need ATP

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Overview cellular respirationcells need ATP

• Cells need ATP

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Go to page 73 of Study Guide

• First stage of cell respiration is Glycolysis.
• Requires no oxygen
• The production of ATP by the oxidation of glucose
  
• But first

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Oxidation and Reduction

• Oxidation
• Addition of oxygen
• Removal of hydrogen
• Loss of electrons

• Reduction
• Removal of oxygen
• Addition of hydrogen
• Addition of electrons

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NAD and FAD

• 1. Each metabolic reaction is catalyzed by its
  own enzyme.  2. As a metabolite is oxidized,
  NAD accepts two electrons and a hydrogen ion
  (H) results in NADH H. 3. Electrons
  received by NAD and FAD are high-energy
  electrons and are usually carried to the
  electron transport system.

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• 4. NAD is a coenzyme of oxidation-reduction
  since it both accepts and gives up electrons.
   5. Only a small amount of NAD is needed in
  cells each NAD molecule is used over and over.
  6. FAD coenzyme of oxidation-reduction can
  replace NAD FAD accepts two electrons, becomes
  FADH2.

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FAD and NAD
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Catabolic Pathways

• Recall this is breaking down of complex molecules
• 2 types of pathways
• Fermentation partial pathway requires no oxygen
• Cellular respiration oxygen is consumes

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Glycolysis

• Glycolysis is the anaerobic catabolism of
  glucose.
• It occurs in virtually all cells.
• In eukaryotes, it occurs in the cytosol.
• C6H12O6 2NAD -gt 2C3H4O3 2NADH 2H

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Glycolysis

• Outside mitochondria in cytoplasm
• Does not require nrg
• Breaks down glucose into 2 pyruvates

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4 stages in glycolysis ( page 73 study guide)

• Phosphorylation
• Lysis
• Oxidation
• ATP formation
• Krebstca

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Glycolysis is enzyme driven

• Shockwave observe the step by step process as
  you look at your study guide as well as the
  animation.
• This animation goes well with the study guide Bio
  231 Cell Biology Laboratory Home Page go to
  glycolysis

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Energy from glycolysis
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Summary of yield

• One glucose molecule is converted into
• 2 pyruvate
• 2 ATP
• 2 NADH H

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• If molecular oxygen is present the pyruvate
  enters the mitochondria

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Mitochondria

• Mitochondria are membrane-enclosed organelles
  distributed through the cytosol of most
  eukaryotic cells.
• Their main function is the conversion of the
  potential energy of food molecules into ATP.

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Mitochondria have

• outer membrane encloses the entire structure
• inner membrane that encloses a fluid-filled
  matrix
• between the two is the intermembrane space
• the inner membrane is elaborately folded with
  shelflike cristae projecting into the matrix.
• a small number (some 510) circular molecules of
  DNA

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You must be able to draw the mitochondria.

• Go to page 76 of study guide and make a drawing
  of a mitochondria including the labels. This
  will be a graded assignment which must be
  accurate, and to scale. IB standards are in
  place.

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Krebstca go to page 74 study guide

• Prior to entering the Krebs Cycle, pyruvate must
  be converted into acetyl CoA .
• This is achieved by removing a CO2 molecule
  (decarboxylation) and hydrogen (oxidation) from
  pyruvate.
• The hydrogen is accepted by NAD -?NADH
• An enzyme called coenzyme A is combined with the
  remaining acetyl to make acetyl CoA

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Transition of pyruvate to acetyl CoA
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The Krebs Cycle Page 74

• An acetyl group is transferred from acetyl CoA
  (2C) to oxaloacetate (4C) to make Citrate (6C)
• Citrate is converted back to oxaloacetate during
  cycle
• 3 types of reactions
• Decarboxylation
• Oxidations
• Substrate level phosphorylation

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To review

• Krebstca

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Summary of yield remember there are 2 pyruvates
per glucose
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Points to remember

• Each NADH made in the mitochondria yields 3 ATP
• NADH made in outside mitochondria yields 2 ATP
• FADH yields 2 ATP
• You will need this information as we discuss the
  electron transport chain.

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Electron transport chain overview

• Krebstca (if cant open go to bio home page at
  the bottom of page )

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Harvesting the nrg

• So far we have from glycolysis and the Krebs
  cycle (per molecule of glucose)
• ATP by substrate phosphorylation
• NADH and FADH2 (which account for most of
  the nrg stored from the metabolism of glucose )

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Electron Transport Chain

• A collection of molecules found in the inner
  mitochondrial membrane

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Electron transport chain overview

• Krebstca (if cant open go to bio home page at
  the bottom of page )

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Key points

• Protons are translocated across the membrane,
  from the matrix to the intermembrane space
• Electrons are transported along the membrane,
  through a series of protein carriers
• Oxygen is the terminal electron acceptor,
  combining with electrons and H ions to produce
  water
• As NADH delivers more H and electrons into the
  ETS, the proton gradient increases, with H
  building up outside the inner mitochondrial
  membrane, and OH- inside the membrane.

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• VCAC Cellular Processes ATP Synthase The Movie
• http//www.wiley.com/legacy/college/boyer/04700037
  90/animations/electron_transport/electron_transpor
  t.swf
• (follow electron transport )
• respiration info (go to electron transport chain)
• Animations (should be mcgraw hill)

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Key Points to remember

• 1. NADH and FADH2 donate electrons to the series
  of electron carriers in the ETC
• The final electron acceptor is Oxygen creating
  water as a by product of cell resp.

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Points cont.

• Electron transport is coupled to ATP by
  chemiosmosis. Page 75 study guide)
• Animation of Chemiosmosis during Aerobic
  Respiration

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Points cont.

• At certain steps along the chain, electron
  transfer causes electron carrying protein
  complexes to move Hydrogen ions from the matrix
  to the intermembrane space storing energy as a
  proton-motive force (hydrogen gradient)
• Animation of Chemiosmosis Proton Pumping

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Points continued

• As hydrogen diffuses back into the matrix through
  ATP synthase, its exergonic passage drives the
  endergonic phosphorylation of ADP
• Electron transport system
• (follow NADH and FADH2 as well as counting number
  of ATP made.)

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Related Metabolic Pathways

• Without oxygen electronegetive oxygen to pull the
  electrons down the transport chain, oxidative
  phosphorylation ceases.
• Fermentation provides another avenue for the
  synthesis of ATP.

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Fermentation

• 1. The oxidizing agent of glycolysis is NAD ,
  not oxygen.
• But glycolysis generates 2 ATP by oxidative
  phosphorylation.
• Fermentation regenerates ATP by transferring
  electrons are transferred to pyruvate.

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• The miracle of fermentation

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Process of alcohol fermentation

• Fermentation consists of glycolysis plus
  reduction of pyruvate to either lactate or
  alcohol and CO2.
• NADH passes its electrons to pyruvate instead of
  to an electron transport system
• NAD is then free to return and pick up more
  electrons during earlier reactions of glycolysis.

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Anaerobic fermentation in yeast

• Fermentation pathways

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Alcohol fermentation

• pyruvate is first decarboxylated to yield a
  2-carbon substance acetaldehyde. Acetaldehyde is
  then reduced as hydrogens are transferred from
  NADH to acetaldehyde to produce ethyl alcohol.

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lactic acid fermentation

• pyruvate is used as the direct acceptor of the
  hydrogens removed from NADH. The end product is a
  molecule of lactic acid. Lactic acid or lactate
  is a common by-product of anaerobic respiration
  in muscle cells.

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Anaerobic fermentation humans

• Fermentation pathways

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Advantage of Fermentation

• provides quick burst of ATP energy for muscular
  activity.

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Disadvantage of Ferm.

• lactate is toxic to cells. lactate changes pH
  and causes muscles to fatigue. lactate is sent to
  liver, converted into pyruvate then respired or
  converted into glucose.
• Two ATP produced per glucose molecule during
  fermentation

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Metabolism of fats

• 1. Most dietary fats are triglycerides that can
  be used as an energy source only if broken down
  into glycerol and fatty acids.
• 2. Beta oxidation decomposes fatty acids into
  segments (ketones) that are converted into acetyl
  coenzyme A (2C) that can then enter the citric
  acid cycle. 3. The glycerol portion can also
  enter the glycolysis pathway .

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• Go to metabolism of fats Alternative energy
  sources

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Metabolism of Proteins

• To be used for energy, the nitrogen-containing
  groups must first be stripped from the amino
  acids (deamination). The deaminated portions of
  the amino acids can be decomposed to carbon
  dioxide and water, and enter the citric acid
  cycle at various sites to yield energy. to fat.
  
• Go to proteins Alternative energy sources

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Go through this site and do review questions.

• Cell Respiration Introduction
• General Human Biology
• This is the web site which goes with your new
  book (chapter 9) Raven Johnson Biology

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• Link to AP lab ( go through each concept)
• LabBench
• Review les mitochondries