Cellular respiration

Cellular respirationThe process of recharging ATP

Textbook pp 95-100

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You think… Is ‘Respiration’ the same as ‘Breathing’??

No. Respiration is….

The release of energy from food

ATP

ATP is an energy carrier within the cellATP can’t be stored nor can it be

exported, so it must be used as it is produced

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The Regeneration of ATPCellular respiration is the process that recharges ATP

Go to TB p 95

A living organism uses ATP continuously, but ATP is a renewable resource that can be regenerated by the addition of phosphate to ADP. The energy for this comes from the breakdown of food molecules.

Other CarriersGo to p 96

The need for energyThink of 5 reasons a human body,

including all its cells, needs energy

creation (such as protein and polysaccharide manufacture)

active transport (ion pumps, cytosis)movement (microtubules, actin

and myosin filaments, cilia)generate heat to maintain body temperature

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Cellular respirationLook up the equation for cellular respiration.

Complete Worksheet

Cellular respirationThe complete oxidation of glucose involves

over 20 different reactions, each catalysed by a different enzyme.

Respiration does not break down glucose in a single step.

Instead, glucose is broken down gradually releasing about 35% of the available energy to produce ATP. The rest is lost as heat energy

Overview of respiration3 major processes

1.Glycolysis

2.The Krebs Cycle

3.Electron Transport

Use your Text Books to match the steps to their major functions and correct order

Step

1.

2.

3

Electron Transport

Glycolysis

The Krebs Cycle

The breakdown of 6 Carbon Glucose to two 3 Carbon PyruvateOccurs in the cytoplasm

NAD carriers get filled with Hydrogen to form NADHOccurs in the inner matrix of the mitochondria

The stage where most ATP are charged upElectrons are passed over cytochromes in the on the membranes of the mitochondria

CELLULAR RESPIRATION 2Learning Intentions: Understand GLYCOLYSIS Understand Formation of Acetyl CoA

HW – WB pp 158

GlycolysisTaking a 6 Carbon Glucose and breaking it into two 3 Carbon molecules.

2 molecules of ATP are used, but 4 are given off. Therefore, we have a net (overall) gain of 2 ATP

Process 1: Glycolysis

Net yield is: 2ATP, 2NADH & 2 pyruvate

Link reaction between Glycolysis and The Krebs Cycle: occurs in the mitochondrial matrix

The pyruvic acid in Glycolysis loses a Carbon (through the creation of a CO2)

It is now a 2 Carbon compound called acetyl

Acetyl is carried by Coenzyme A – together they are Acetyl CoA

Acetyl CoA moves to the Krebs Cycle.

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CELLULAR RESPIRATION 3Learning Intentions: Identify Mitochondrial structureUnderstand Electron Transport

First - MitochondriaUse TB p 81 to label

this

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Krebs cycle (citric acid cycle): takes place in the mitochondrial matrix

See TB p 98The major points:

• The acetyl group (created in the linking reaction) passes into a cycle of reactions .

• The acetyl group (2 C) combines with a 4C group to create a 6C molecule

• 2 lots of Carbon Dioxide are released (waste)• 2 ATP produced• Many NADs fill with Hydrogen to form NADH2• The NADH2s are transported to the electron transport

chain• Because we lost 2C molecules in our waste, we are now

back to the start.

Electron & H+ transport coupled with ATP synthesis

Electron transport chain: takes place in and across the cristae

It is at this point most of the ATP molecules are charged

One molecule of glucose charges up to 38ATP, with 34 able to be charged in the electron transport chain

NADH2 arrive from glycolysis and Krebs cycle, bringing in Hydrogens

The hydrogens and electrons are passed down the electron transport chain.

ATP is produced

respiration of 1 molecule of glucoseProcess ATP produced

glycolysis 2

Krebs cycle 2

Electron transport34

Net ATP yield 38

22Cellular respiration song

CELLULAR RESPIRATION 4Learning Intentions: Distinguishing between aerobic and anaerobic respiration

Other substrates for respirationStarchGlycogenTriglycerides (fatty

acids are broken down into 2C molecules and enter the Krebs cycle as acetyl CoA; glycerol enters glycolysis as a triose phosphate)

Proteins (very rarely: amino acids are deaminated and converted into pyruvate, acetyl CoA or Krebs cycle intermediates)

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Aerobic respirationWhen oxygen is present, pyruvate follows a

certain pathway:

It enters the mitochondria and undergoes a link reaction

The product of the link reaction enters the Krebs cycle (or Citric acid cycle)

And finally, H atoms (H+ and e-), that have been removed during the steps above, enter the electron transport chain

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Anaerobic respirationOccurs in the cytoplasmDoes not require oxygen but does occur in its

presenceStill involves Glycolysis, but does not follow

through the Acetyl CoA Link reaction Generates a very small amount of ATPProduces poisonous bi-products

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Fate of pyruvate when there is no oxygen

Alcoholic fermentation in yeast cells

Lactic acid fermentation in muscle cells

Lactic acid is transported to the liver and oxidised to pyruvate & then to glucose. The oxygen needed for this is called the ‘oxygen debt’ of anaerobic respiration

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