RESPIRATION

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RESPIRATION

• 4.1 Glycolysis

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Cliff Climb Starter
To reach the top of the cliff, describe 10 things
youve learnt about ATP and energy.........
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• Learning Objectives

• Success Criteria

• Compare the key stages of aerobic and anaerobic
  respiration
• Accurately describe the chemical reactions at
  each stage of glycolysis
• Make a model of the chemical changes that occur
  in glycolysis

• Understand where glycolysis fits into the overall
  process of respiration
• Describe the main stages of glycolysis
• Describe the main products of glycolysis

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GCSE

• Write down as much as you can remember from GCSE
  about respiration.
• You have 5 minutes.

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GCSE Recap

• This is a chemical reaction.
• It occurs in every living cell.
• It is not breathing!!!
• There are two types - Aerobic and Anaerobic.
• Aerobic requires oxygen.
• Anaerobic does not.

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Key points about respiration from GCSE and AS
Biology?

• All living cells respire.
• During respiration a chemical reaction occurs in
  which sugars are oxidised to release energy.
  Carbon dioxide and water are released during
  these reactions.
• Glucose enters cells by diffusion and facilitated
  diffusion.
• When there is a shortage of oxygen, muscles
  produce lactate in respiration.

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• Mitochondria consist of a double layer of
  membrane surrounding a central matrix. The inner
  membrane is folded to form cristae.
• Coenzymes are complex organic molecules that are
  used by enzymes to accept or donate molecules
  involved in a reaction. They are often referred
  to as Helper molecules as they carry chemical
  groups or ions about, e.g. NAD removes H and
  carries it to other molecules.
• An electron is a negatively charged particle
  surrounding the nucleus of an atom.
• A proton is a positively charged particle found
  in the nucleus of an atom.

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A2 Level Respiration

• Food source of energy for all animals.
• Carbohydrates and fats store chemical energy.
• Energy is released in series of controlled
  reactions.
• This process is known as RESPIRATION.
• ATP is the product and this is the cells energy
  currency.
• Energy yielding reactions are coupled with energy
  requiring reactions.
• i.e. Muscle contraction

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A2 Level Respiration

• C6H12O6 6O2 6CO2
  6H2O 38 ATP
• Only an overview!!
• Respiration is a series of reactions in which
  energy is transferred from organic compounds,
  such as carbohydrates, to the temporary energy
  store, ATP.

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Respiration
The process of respiration can be split into 4
stages.

1. Glycolysis
2. Link reaction
3. Krebs Cycle
4. Electron Transport Chain

In what part(s) of the cell does respiration take
place?
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The Powerhouse of the Cell

• Mitochondria
• Found in all cell types.
• Found in higher numbers in cells that have higher
  energy demands.
• 1µm diameter 10µm long.

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Structure of a Mitochondrion
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Structure of a Mitochondrion
Outer membrane
DNA
Ribosomes
Crista (fold in inner membrane)
Stalked particles
Matrix
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What Happens Where?

• Glycolysis Cytoplasm of the cell.
• Link reaction Matrix of the mitochondria.
• Krebs cycle Also in the matrix.
• Electron transfer chain Utilises proteins found
  in the membrane of the christa.

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Glycolysis

• This is the 1st stage.
• It occurs in the cytoplasm.
• Its a splitting thing!

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GLYCOLYSIS (carbohydrate splitting)

• First stage of aerobic respiration anaerobic
  respiration.
• Doesnt need O2 so this stage is anaerobic!
• Occurs in the cytoplasm of all living cells
• There are 2 stages of Glycolysis
• Phosphorylation
• Oxidation

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Glucose
ATP
ADP
Phosphorylation
ADP
ATP
H2O
Hydrolysis
4Pi
4ADP
4ATP
Oxidation
4H
2NADH 2H
2NAD
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Glucose
ATP
ADP
Phosphorylation
Hexose phosphate
ADP
ATP
Hexose bisphosphate
H2O
Hydrolysis
2X Triose phosphate
4Pi
4ADP
4ATP
Oxidation
4H
2NADH 2H
2NAD
2X Pyruvate
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Stage 1 - Phosphorylation

• Glucose is phosphorylated by adding 2 phosphates
  from 2 molecules of ATP.
• Glucose is split using water(hydrolysis).
• 2 molecules of triose phosphate are created and 2
  molecules of ATP are used up.

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Stage 2 - Oxidation

• 4 ATP are produced, but 2 were used at the start,
  so theres a net gain of 2ATP.
• Coenzyme NAD collects the hydrogen ions forming
  2 Reduced NAD
• (NADH H)
• The triose phosphate is oxidised (loses
  hydrogen), forming 2 molecules of pyruvate.

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Glycolysis
NAD 2H ? NADH H(oxidised form )
(reduced form) NB Rather then write NADH,
examiners often simply refer to it as reduced NAD
or reduced coenzyme
Glycogen

• You start with glycogen.

2 ATP
4 ATP
4 ADP 4Pi
Glyceraldehyde 3-phosphate (3C x 2)
Pyruvate (3C x2)
Glucose (6C)
2H x 2
NAD
Reduced NAD
2 ADP
Nicotinamide adenine dinucleotide So it gains
electrons
You finish with Pyruvate
Why is Glycolysis termed anaerobic? What is the
NET production of ATP?
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The sums

• The end products of glycolysis are pyruvate and
  reduced NAD
• Energy is released during this reaction.
• 4 molecules of ADP Pi converted to 4 molecules
  of ATP.
• So net gain of 2 molecules of ATP
• 2 pairs of hydrogen atoms produced
• 2 Molecules of pyruvate.

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Products of Glycolysis

• 2 reduced NAD (NADH H)
• 2 Pyruvate
• 2 ATP

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The Fate of Pyruvate!

• THIS DEPENDS ON THE AVAILABILITY OF OXYGEN!!!

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Glycolysis - group task

• Referring to your textbook (pages 50-51) and
  information from the PowerPoint slides, work in 4
  groups to model the chemical changes that occur
  in glycolysis
• Glucose activated by phosphorylation
• Phosphorylated glucose split into triose
  phosphate
• Oxidation of triose phosphate
• Production of Pyruvate and ATP
• Now join the models together in the right order
  to summarise the key events of glycolysis

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• Learning Objectives

• Success Criteria

• Compare the key stages of aerobic and anaerobic
  respiration
• Accurately describe the chemical reactions at
  each stage of glycolysis
• Make a model of the chemical changes that occur
  in glycolysis

• Understand where glycolysis fits into the overall
  process of respiration
• Describe the main stages of glycolysis
• Describe the main products of glycolysis