Cell respiration haf 1

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?