cell respiration haf 1
TRANSCRIPT
CELL RESPIRATION
GCSE – What do you know?
What is the common misconception?
Respiration is NOT……..
Respiration
“Controlled Release of Energy”
Production of ATP (Adenosine Triphosphate) from organic molecules.
Occurs within the cells of ALL organisms.
Aerobic Cell Respiration – Requires Oxygen
Summary Equation
Glucose + Oxygen = ENERGY (ATP) + Carbon Dioxide + Water
Raw Materials Waste Products
Anaerobic Cell Respiration – Oxygen is not used
Animals (including humans)
Glucose ENERGY (ATP) + Lactate (lactic acid) Yeast Cells
Glucose ENERGY (ATP) + Ethanol +Carbon Dioxide
REDOX Reactions
OXIDATION OXIDATION
• Gain of oxygen atomsGain of oxygen atoms• Loss of hydrogen Loss of hydrogen
atomsatoms• Loss of electrons from Loss of electrons from
a substancea substance
REDUCTIONREDUCTION
• Loss of oxygen atomsLoss of oxygen atoms• Gain of hydrogen Gain of hydrogen
atomsatoms• Gain of electrons to a Gain of electrons to a
substancesubstance
Aerobic Respiration - Overview
http://www.cellsalive.com/cells/cell_model.htm
If Glucose is the Substrate Glycolysis = 1If Glucose is the Substrate Glycolysis = 1stst Stage in Stage in anyany Respiration Respiration
•THIS PATHWAY OCCURS IN THE CYTOPLASM
•LESS AMOUNT OF ENERGY IS PRODUCED
•PARTIAL OXIDATION OF GLUCOSE OCCURS, AND DOES NOT REQUIRE OXYGENDOES NOT REQUIRE OXYGEN
•IT OCCURS IN BOTH PROKARYOTES & EUKARYOTES
•4 Steps in Glycolysis
STEP 1: Phosphorylation STEP 1: Phosphorylation
GLUCOSE GLUCOSE HEXOSE HEXOSE
BIPHOSPHATE BIPHOSPHATE
2 ATP2 ATP 2 ADP2 ADP
STEP 2: LYSISSTEP 2: LYSIS
HEXOSE HEXOSE BIPHOSPHATE BIPHOSPHATE
2 molecules 2 molecules TRIOSE TRIOSE
PHOSPHATE PHOSPHATE
STEP 3: OXIDATIONSTEP 3: OXIDATION
2 molecules of 2 molecules of TRIOSE TRIOSE
PHOSPHATE PHOSPHATE
3 CARBON 3 CARBON COMPOUND COMPOUND
carrying carrying 2PO2PO44
groups eachgroups each
2 NAD2 NAD++ 2 NADH + H2 NADH + H++
Triose Phospate lose Triose Phospate lose electrons and electrons and
hydrogenshydrogens
NADNAD+ + = nicotinamide adenine dinucleotide= nicotinamide adenine dinucleotideNADNAD++ and NADH are electron carriers (and co-enzymes) they and NADH are electron carriers (and co-enzymes) they
carry electrons from one reaction to another. G3P (triose carry electrons from one reaction to another. G3P (triose phosphate) is oxidised NADphosphate) is oxidised NAD+ + is reduced (gains 2 electrons is reduced (gains 2 electrons
and 2 hydrogens). These are carried to the electron and 2 hydrogens). These are carried to the electron transport chain (we will see later).transport chain (we will see later).
STEP 4: ATP formationSTEP 4: ATP formation
Two Two 3 3 CARBON CARBON
COMPOUND COMPOUND formedformed
2 PYRUVATE 2 PYRUVATE MOLECULESMOLECULES
4 ADP4 ADP 4 ATP4 ATP
Enzymes remove the 2 phosphate groups and provide them to ADP for ATP formation
Draw your own overview of Glycolysis
STEP IV: ATP formationSTEP IV: ATP formation
STEPS INVOLVED IN GLYCOLSISSTEPS INVOLVED IN GLYCOLSIS
STEP III: OXIDATION of Triose phosphateSTEP III: OXIDATION of Triose phosphate
STEP II: LYSISSTEP II: LYSIS
STEP I: PHOSPHORYLATIONSTEP I: PHOSPHORYLATION
glucoseglucose
Hexose Hexose biphosphate (6c)biphosphate (6c)
2 triose phosphate 2 triose phosphate (3c) molecules(3c) molecules
2 pyruvate 2 pyruvate moleculesmolecules
2 ATP2 ATP
2 ADP2 ADP
2 INTERMEDIATE 2 INTERMEDIATE (3c) molecules(3c) molecules
4 ADP4 ADP
4 ATP4 ATP
2 NAD2 NAD++ 2 NADH + H2 NADH + H++
• The fate of Pyruvate is decided by the is decided by the availability of oxygen.availability of oxygen.
OXYGEN =
NO oxygen =
In animalsIn animals
LINK REACTION LINK REACTION
Aerobic Respiration - Overview
Aerobic Respiration - Overview
• Stages in the Aerobic respiration:• Link Reaction: Pyruvate is transported into the
matrix of the mitochondria.• Krebs cycle: carbon fragments (C2) are progressively
decarboxylated to yield ATP and reduced coenzymes.
• Electron Transport System (Oxidative phosphorylation in terms of chemiosmosis): reduced coenzymes are used to generate more ATP.
http://www.cellsalive.com/cells/cell_model.htm
Aerobic Respiration occurs in the mitochondria
Glycolysis occurs in the Cytoplasm
1) LINK REACTION – Matrix of the Mitochondria
• Pyruvate passes from the cytosol to the inner passes from the cytosol to the inner mitochondrial matrix mitochondrial matrix by active transport
Each molecule Each molecule of of PYRUVATEPYRUVATE
2 CARBON 2 CARBON COMPOUND COMPOUND ACETYL CoAACETYL CoA
NADNAD++ NADH + HNADH + H++
COCO22 CoACoA
1) LINK REACTION – Oxidative Decarboxylation
What is the net yield of Acetyl CoA per glucose molecule?
Draw your own overview of the Link Reaction
Mitochondrial Matrix
2) Kreb Cycle – Lots of Carbons!!
• Where? • C2 = Acetyl • C2 + C4 (oxaloacetate) = C6 (Citric Acid/Citrate)
Blue Carbons from the Mitochondria
Carbons from original glucose molecule
2) Kreb Cycle – Lots of Carbons!!
• C2 + C4 (oxaloacetate) = C6 (Citric Acid/Citrate)• C6 oxidative decarboxylation = C5
NAD+ is reduced
C6 decarboxylated to produce C5
2) Kreb Cycle – Lots of Carbons!!
• C5• C5 oxidative decarboxylation = C4
NAD+ is reduced
C5decarboxylated to produce C4
2) Kreb Cycle – Lots of Carbons!!• C4 • Substrate level phosphorylation and electron
transport acceptors
NAD+ is reduced
ADP reduced to ATP
FAD is reduced to FADH2
Flavin Adenine Dinucleotide = electron carrier
Draw your own overview of the Kreb’s Cycle
• The energy stored in NADH and FADH is used to The energy stored in NADH and FADH is used to generate a proton gradient across the inner generate a proton gradient across the inner membrane.membrane.
• The energy of the proton gradient is used to The energy of the proton gradient is used to make ATP (phosphorylate). make ATP (phosphorylate).
• In chemistry, the term proton refers to the hydrogen ion, H+.
3) Oxidation phosphorylation – 3) Oxidation phosphorylation – The Proton StoryThe Proton Story
•In the mitochondrial matrix electrons from NADH and FADH are transferred down Electron Transport Chains (use of coenzymes and enzymes). As a result the H+ ions ( protons) are transferred from the matrix into the inter membrane space through proton pumps.•H+ build up in the inter membrane space and create and electrochemical gradient. •H+ flow back into the matrix through ATP synthetase. This releases energy which allows phosphorylation of ADP to ATP in the matrix.
Oxidation phosphorylation Oxidation phosphorylation – The Proton Story– The Proton Story
RESPIRATION CHEMIOSMOSISRESPIRATION CHEMIOSMOSIS
.
I am a proton! I start in the mitochondrial matrix. A number of times a day I go on an adventure. Can
you write about my adventure.
IB Question
• Explain the process of aerobic cellular respiration. (8 marks)
In animalsIn animals
LINK REACTION LINK REACTION
http://www.cellsalive.com/cells/cell_model.htm
Anaerobic Respiration also occurs in the Cytoplasm
Glycolysis occurs in the Cytoplasm
Anaerobic Respiration – Lactic Acid Fermentation
• When do humans use lactic acid fermentation?
• Lactic acid is poisonous, what happens to lactic acid after it has been produced?
When our bodies convert from aerobic to anaerobic respiration, we start making lactic acid.
As soon as this begins, the body starts building an oxygen debt. This is equivalent to the amount of oxygen it would have used if aerobic respiration had continued.
Oxygen Debt - Lactic acid
Anaerobic Respiration – Alcoholic Fermentation
• What organism does this occur in?• Why is this useful to humans?