Glycolysis 9/21/2009 1

Transcription

1 Glycolysis 9/21/2009 1

2 Glycolysis glycolysis is another word for the breakdown of glucose if glucose is broken done in the presence of oxygen, carbon dioxide, and water you have the formula: C6H12O6 + 6O2 6CO2 + 6H2O glucose + 6 oxygen 6 carbon dioxide + 6 water cell takes the glucose apart and then captures then energy a little bit at a time 9/21/2009 2

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4 Calories the end product from the formula on the previous slide gives off about 3811 calories per gram of glucose (sugar) a calorie is a unit of heat, more specifically how much heat is needed to raise the temperature 1 degrees Celsius glucose has A LOT of energy--more than ATP and NADPH 9/21/2009 4

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6 Glycolysis glycolysis is the first stage in the breaking down of glucose takes place in the cytoplasm of the cell in glycolysis, a series of enzymes speed up chemical reactions that change glucose, one step at a time, into different molecules 9/21/2009 6

7 First Step of Breaking Down Glucose a molecule of glucose goes through a few chemical reactions these reactions split the 6-carbon sugar into two 3-carbon PGAL (phosphoglyceraldehyde) molecules two molecules of ATP are used in this first process the cell must use some of the energy it has stored away to begin the breakdown of glucose 9/21/2009 7

8 Next Few Steps of Glycolysis the 2 PGAL molecules are turned into 2 molecules of pyruvic acid (3-carbon compound) the energy from the 2 PGAL molecules is used to make 4 molecules of ADP and 2 molecules of NADH NADH is an energy storing compound similar to NADPH 9/21/2009 8

9 Next Few Steps of Glycolysis (cont.) in glycolysis 4 molecules of ATP are made into 4 molecules of ADP there is a gain of 2 molecules of ATP during glycolysis the 2 molecules of ATP produced are more than 2% of the total chemical energy in glucose 9/21/2009 9

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12 Respiration as long as there is oxygen, respiration can take place aerobic processes, like respiration, need oxygen respiration is the process that involves oxygen and breaks down food molecules to release energy 9/21/

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14 Respiration (cont.) the pyruvic acid produced by glycolysis is what is used in respiration when the pyruvic acid is broken down, the energy goes into 34 more molecules of ATP chemical reactions of respiration take place in the mitochondria the reactions are enclosed by the inner membrane the 2 nd set of reactions are inside the inner membrane 9/21/

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16 Respiration Info. respiration is a synonym for breathing both plants and animals use some type of respiration--whether it s breathing or cellular respiration 9/21/

17 Krebs Cycle the first set of reactions in respiration are called the Krebs Cycle--discover was Hans Krebs the Krebs Cycle doesn t make an end product, but rather is a continuous circle of reactions known as citric acid cycle since citric acid is formed in the cycle 9/21/

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19 Kreb s Cycle (cont.) the pyruvic acid, produce by glycolysis, travels from the cytoplasm to the mitochondrion in the first reaction, the pyruvic acid is broken down in CO2 and a 2-carbon acetyl group the acetyl-coenzyme A passes the 2-carbonsof the acetyl group into the Krebs Cycle where they are joined with a 4-carbon compound that then produces citric acid, 6-carbon compound 9/21/

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21 Krebs Cycle (cont.) there are nine reactions and nine intermediates that make up the Krebs Cycle two places CO2 is released four spots where a pair of high-energy electrons are taken in by electron carriers changes NAD+ to NADH changes FAD to FADH2 a molecule of GDP (close to ADP) is converted to GTP (close to ATP) 9/21/

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23 Krebs Cycle Summary 2 carbon atoms added (from breakdown of pyruvic acid) 2 carbon atoms removed (in 2 molecules of CO2) 3 molecules of NAD+ converted to NADH 1 molecule of FAD converted to FADH2 1 molecule of ADP converted to ATP CO2 produced by the cycle is released from the cell 9/21/

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25 Electron Transport in the Mitochondria electrons from NADH and FADH2 are passed to many electron transport enzymes which form an electron transport chain at the end of the chain, an enzyme combines electrons from the chain, H+ (hydrogen ions) from the fluid in the cell, and O2 (oxygen) to make H2O (water). oxygen is the final electron accepter and is needed to obtain energy from NADH and FADH2 9/21/

26 ATP Formation the mitochondria accepts electrons, while some enzymes pump hydrogen ions outside the inner membrane movement of hydrogen ions is what powers the making of ATP the movement of a pair of electrons down the electron transport chain produces enough energy to make 3 ATP molecules from ADP 9/21/

27 ATP Formation (cont.) the more H ions on the outside makes the outside more positively charged then the inside the difference in the charges gives the energy needed to make ATP from ADP the mitochondrion membrane lets the enzymes pump ions out, but won t let them come back in 9/21/

28 Totals glycolysis makes a net-gain of 2 ATP molecules and passes electrons to 2 NADH molecules the energy from he NADH molecules makes 10 ATP molecules (4 from Glycolysis & 6 from the first step of the Kreb s cycle) in respiration, 6 more NADH, 2 ATP, and 2 FADH2 molecules are made in the Krebs Cycle 9/21/

29 Totals (cont.) electrons use the energy from NADH and FADH2 to produce 22 ATP molecules between glycolysis and respiration 36 ATP molecules are made from one molecule of glucose the energy in the 36 ATP molecules is about 37-38% of the total available chemical energy in glucose Still makes the human body more efficient than a car engine Where does the other 62% of the energy released go? 9/21/

30 Getting Energy from Food complex carbs. are broken down into simple sugars which are them converted to glucose lipids and proteins can be broken down to go through glycolysis and the Krebs Cycle 9/21/

31 How Important is Oxygen?? without oxygen, electron transports can happen, the Krebs Cycle will stop, and the making of ATP in the mitochondria will also stop if our bodies don t get enough oxygen, then they ll try to work from the oxygen from glycolysis and that is not enough oxygen has a major role in the mitochondria of a cell 9/21/

32 Balance photosynthesis and respiration can be thought of as opposite reactions photosynthesis gives energy, respiration takes energy respiration and photosynthesis equations are reverse of each other the products of photosynthesis are the reactants for the breaking down of glucose 9/21/

33 Balance (cont.) the products of breaking down glucose, are the reactants in photosynthesis 9/21/

34 Fermentation 9/21/

35 Fermentation in order for glycolysis to continue, NADH must be converted back to NAD+ the only way to do that is with fermentation fermentation is an anaerobic process, meaning it doesn t require oxygen NADH is converted to NAD+ by adding extra electrons in NADH to an organic molecule acting as an electron accepter 9/21/

36 Fermentation (cont.) fermentation lets cells carry out energy production in the absence of oxygen together, glycolysis and fermentation make 2 ATP molecules from a molecule of glucose the two ways to change NADH to NAD+ is alcoholic and lactic acid fermentation 9/21/

37 Lactic Acid Fermentation pyruvic acid that accumulates as a result of glycolysis can be turned into lactic acid lactic acid fermentation produces lactic acid this process regenerates NAD+ so that glycolysis can continue pyruvic acid + NADH lactic acid + NAD+ lactic acid is often produced in muscles when one is doing rapid exercises 9/21/

38 Lactic Acid Fermentation (cont.) after doing some form of exercise very quickly, your muscles produce ATP by fermentation and during this lactic acid is made 9/21/

39 Alcoholic Fermentation alcoholic fermentation occurs in yeasts and other small microorganisms pyruvic acid is broken down to make a 2- carbon alcohol and CO2 alcoholic fermentation produces alcohol pyruvic acid + NADH alcohol +CO2 + NAD+ the carbon dioxide made by yeast during fermentation makes breads rise 9/21/

40 Alcoholic Fermentation (cont.) the CO2 released by fermentation also causes the bubbles in the wines and beers 9/21/