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IB Biology 3.7 Cell Respiration.

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Presentation on theme: "IB Biology 3.7 Cell Respiration."— Presentation transcript:

1 IB Biology 3.7 Cell Respiration

2 Relationship Between Photosynthesis and Respiration
Products of photosynthesis are reactants in respiration

3 3.7 Assessment Statements
Define cell respiration. State that, in cell respiration, glucose in the cytoplasm is broken down by glycolysis into pyruvate, with a small yield of ATP. Explain that, during anaerobic cell respiration, pyruvate can be converted in the cytoplasm into lactate, or ethanol and carbon dioxide, with no further yield of ATP. Explain that, during aerobic cell respiration, pyruvate can be broken down in the mitochondrion into carbon dioxide and water with a large yield of ATP.

4 3.7.1 Define cell respiration
The break-down of energy containing molecules into products and energy that can be used by the organism Glucose is a very energetic molecule. Releasing all of that energy at once would be too much to be useful (think burning a sugar). Therefore, respiration involves a gradual, step-wise release of energy in smaller increments.

5 Boardworks A2 Biology Respiration What is respiration? Respiration is the process by which organisms extract the energy stored in complex molecules and use it to generate adenosine triphosphate (ATP). In this way they obtain energy to fuel their metabolic pathways. ATP provides the immediate source of energy for biological processes such as active transport, movement and metabolism. ATP

6 Adenosine triphosphate
Boardworks A2 Biology Respiration Adenosine triphosphate ATP contains a sugar (ribose), a base (adenine) and three phosphate groups. adenine ribose phosphates When ATP is hydrolyzed to form ADP and inorganic phosphate, 30.5 kJ of energy are released. + 30.5 kJ ATP H2O ADP inorganic phosphate

7 Why ATP? Biological systems transfer the energy in glucose to ATP because unlike glucose… glucose ATP ATP releases its energy instantly in a single reaction. The hydrolysis of ATP releases a small amount of energy, ideal for fueling reactions in the body.

8 Phosphorylation: 2 ways to make ATP
Boardworks A2 Biology Respiration Phosphorylation: 2 ways to make ATP The addition of an inorganic phosphate group (Pi) to a molecule like ADP is called phosphorylation. ADP is phosphorylated during respiration. Two types of phosphorylation occur during respiration: 1. Substrate-level: glycolysis & Krebs cycle A single reaction involving the direct transfer of a phosphate group from a carbon (organic) molecule to ADP  ATP. Does not produce much ATP (2-4) 2. Oxidative: electron transport chain A series of oxidation reactions that produce sufficient energy to form ATP from ADP and phosphate. (Pi is added to ADP). Produces a lot of ATP (34-38)

9 Oxidation & Reduction Oxidation is the loss of electrons or H atoms from an atom or molecule.   Oxidized atoms or molecules have less energy than they had before they were they were oxidized.    Reduction is the gain of electrons. Reduced atoms or molecules have more energy than before they were reduced.

10 OIL RIG Oxidation Is Loss of electrons Reduction Is Gain of electrons

11 Redox Reactions Reduction-Oxidation
The main chemical reaction in cellular respiration that involves the transfer of electrons from one reactant to another Redox reactions are comprised of both oxidation and reduction reactions that always go together

12 How Redox Reactions Work
Oxidation Reaction The loss of electrons from one reactant. Reduction Reaction The addition of electrons to one reactant

13 Examples of Redox Reactions in Respiration
Glycolysis – the splitting of glucose in the first stage of cellular respiration Several reactions in citric acid cycle

14 Where does respiration occur?
Boardworks A2 Biology Respiration Respiration occurs in all living cells. In eukaryotes the early stages of respiration occur in the cytoplasm. The later stages of respiration are restricted to the mitochondria. Mitochondria contain highly folded inner membranes that hold key respiratory proteins (including the enzyme that makes ATP) over a large surface area. Mitochondria provide an isolated environment to maintain optimum conditions for respiration. Mitochondria have their own DNA and ribosomes, so can manufacture their own respiratory enzymes.

15 State that, in cell respiration, glucose in the cytoplasm is broken down by glycolysis into pyruvate, with a small yield of ATP. = ATP

16 An overview of respiration
Boardworks A2 Biology Respiration 7

17 The first stage of respiration: glycolysis
Boardworks A2 Biology Respiration The first stage of respiration: glycolysis

18 Glycolysis Glycolysis occurs in the cytoplasm
One glucose molecule is broken into two pyruvate molecules in glycolysis (pyruvic acid) Fate of pyruvates depends on presence/absence of oxygen

19 Glycolysis Animations
Glycolysis (Smith) How Glycolysis Works (McGraw Hill) Quiz

20 The structure of the mitochondria
Boardworks A2 Biology Respiration Photo credit: © CNRI / Science Photo Library Mitochondrion, colored transmission electron micrograph (TEM). Mitochondria are a type of organelle found in the cytoplasm of eukaryotic cells. They oxidize sugars and fats to produce energy in a process called respiration. A mitochondrion has two membranes, a smooth outer membrane and a folded inner membrane. The folds of the inner membrane are called cristae, and it is here that the chemical reactions to produce energy take place. Magnification: x62,800 when printed at 10 centimetres wide.

21 Explain that, during anaerobic cell respiration, pyruvate can be converted in the cytoplasm into lactate, or ethanol and carbon dioxide, with no further yield of ATP. ATP

22 An overview of respiration
Boardworks A2 Biology Respiration 7

23 Boardworks A2 Biology Respiration Types of respiration During aerobic respiration, a respiratory substrate, e.g. glucose, is split in the presence of oxygen to release carbon dioxide and water. A large number of ATP molecules are produced, releasing the energy from the glucose. C6H12O O2  6 CO H2O ATP In anaerobic respiration, glucose is converted (in the absence of oxygen) to either lactate or ethanol. The ATP yield is low. C6H12O6  2 C2H5OH CO ATP ethanol C6H12O6  2 C3H6O ATP lactate 23

24 Anaerobic Respiration
Occurs without oxygen Where does it happen? Occurs in cytoplasm of cell Two types Alcohol fermentation Lactic acid fermentation

25 Alcohol Fermentation Occurs in bacteria (and yeast)
Uses glycolysis to produce pyruvate Produces CO2, ethanol and energy

26 Lactic Acid Fermentation
Occurs in humans (or anything with muscles) Uses glycolysis to produce pyruvate Produces lactic acid and energy

27 Fermentation Depending on the type of organism involved there are two types of fermentation:  alcohol fermentation (in yeasts and some bacteria) and lactic acid fermentation (in many micro-organisms and animal muscle cells).

28

29 Boardworks A2 Biology Respiration Coenzymes Coenzymes are molecules that bind with a specific enzyme or substrate, helping to catalyze a reaction. Breaking the bonds between coenzyme and product after a reaction is crucial, otherwise coenzyme concentration will drop, limiting respiratory rate. substrate enzyme coenzyme Three major coenzymes are used in respiration: NAD (nicotinamide adenine dinucleotide) CoA (coenzyme A) FAD (flavine adenine dinucleotide)

30 Boardworks A2 Biology Respiration NAD, FAD and coenzyme A NAD can accept a hydrogen molecule, forming reduced NAD (NADH). nicotinamide NAD+ + 2H NADH + H+ adenine This is used to regenerate ADP in the electron transport chain (ETC). ribose NAD Coenzyme A aids the transition between glycolysis and the Krebs cycle, by converting pyruvate to acetyl coenzyme A. FAD, like NAD, can accept hydrogen to form reduced FAD (FADH2).

31 Explain that, during aerobic cell respiration, pyruvate can be broken down in the mitochondrion into carbon dioxide and water with a large yield of ATP. =ATP

32 Aerobic Respiration Glycolysis Link Reaction Krebs (citric acid) Cycle
Oxidative Phosphorylation Electron Transport Chemiosmosis

33 Overview of Aerobic Respiration Diagram

34 Aerobic Respiration: Part 1 Glycolysis
One glucose molecule is broken into two pyruvate molecules in glycolysis /pyruvic acid Glycolysis occurs in the cytoplasm These pyruvates enter the mitochondria by active transport via a membrane protein

35 Aerobic Respiration: Part 2 Link Reaction
Once inside, the pyruvate is converted to acetyl CoA in the link reaction This link reaction forms NADH and CO2 Acetyl CoA then enters the citric acid cycle

36 Animations Glycolysis (Smith) Krebs cycle (Smith)
Electron Transport System and ATP Synthesis (McGraw Hill) How Glycolysis Works (McGraw Hill) How the Krebs Cycle Works (McGraw Hill) How the NAD+ Works (McGraw Hill)

37 Aerobic Respiration: Part 3 Citric Acid Cycle / Krebs Cycle
FAD / NAD+ accepts hydrogen and a high-energy electron to form NADH / FADH2; These electron carriers (FADH2 / NADH) donate electrons to electron transport chain

38 Aerobic Respiration: Part 4 Oxidative Phosphorylation
These electrons transfer their energy to member proteins (protein pumps) and actively pump protons (hydrogen ions) across inner membrane Oxygen is the final electron acceptor and produces water as a “waste product” The build up of protons (proton gradient) in the intermembrane space of the mitochondria through ATPase; (this is called chemiosmosis) Producing the ATP involves adding a phosphate to ADP. This is Phosphorylation Produces 36/ 38 ATP (per glucose)

39 Aerobic Respiration: Part 4-A Electron Transport
These electrons transfer their energy to member proteins (proton pumps) and actively pump protons (hydrogen ions) across inner membrane Oxygen is the final electron acceptor and produces water as a “waste product”

40 Electron Transport Chain Diagram
cytochrome

41 Aerobic Respiration: Part 4-B Chemiosmosis
Protons build up (making a proton gradeint) in the intermembrane space of the mitochondrion Gradient potential is then turned into ATP as protons flow into matrix of mitochondrion through ATPase / ATP synthase

42 Total ATP Production in Aerobic Respiration

43 Animations Glycolysis (Smith) Krebs cycle (Smith)
Electron Transport System and ATP Synthesis (McGraw Hill) How Glycolysis Works (McGraw Hill) How the Krebs Cycle Works (McGraw Hill) How the NAD+ Works (McGraw Hill)


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