RESPIRATION

1. RESPIRATION 4.1 Glycolysis

2. ‘Cliff Climb’ Starter To reach the top of the cliff, describe 10 things you’ve learnt about ATP and energy.........

3. Learning Objectives Success Criteria • Understand where glycolysis fits into the overall process of respiration • Describe the main stages of glycolysis • Describe the main products of glycolysis • 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

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

5. 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.

6. 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.

7. 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.

8. 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

9. 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.”

10. Respiration The process of respiration can be split into 4 stages. • Glycolysis • Link reaction • Krebs Cycle • Electron Transport Chain In what part(s) of the cell does respiration take place?

11. 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.

12. Structure of a Mitochondrion

13. Structure of a Mitochondrion Outer membrane DNA Ribosomes Crista (fold in inner membrane) Stalked particles Matrix

14. 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.

15. Glycolysis • This is the 1st stage. • It occurs in the cytoplasm. • It’s a splitting thing!

16. GLYCOLYSIS (carbohydrate splitting) • First stage of aerobic respiration & anaerobic respiration. • Doesn’t need O2 – so this stage is anaerobic! • Occurs in the cytoplasm of all living cells There are 2 stages of Glycolysis: • Phosphorylation • Oxidation

17. Glucose ATP ADP Phosphorylation ADP ATP H2O Hydrolysis 4Pi 4ADP 4ATP Oxidation 4H 2NADH + 2H+ 2NAD+

18. 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

19. 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.

20. Stage 2 - Oxidation • 4 ATP are produced, but 2 were used at the start, so there’s 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.

21. 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 Glycolysis 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?

22. 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.

23. Products of Glycolysis • 2 reduced NAD (NADH + H+) • 2 Pyruvate • 2 ATP

24. The Fate of Pyruvate! THIS DEPENDS ON THE AVAILABILITY OF OXYGEN!!!

25. 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

26. Learning Objectives Success Criteria • Understand where glycolysis fits into the overall process of respiration • Describe the main stages of glycolysis • Describe the main products of glycolysis • 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