Presentation on theme: "Metabolism Part 1: Glycolysis"— Presentation transcript:
1 Metabolism Part 1: Glycolysis This tutorial will take you through the basics of glycolysisfor SC 120Click this button to move forward
2 What is the purpose of cellular respiration? To provide Oxygento the cellsTo use cell energyNot really. Some cells can perform respiration without Oxygen!Cells use up energy for all sorts of activities. They need respiration for something elseTo bring Oxygeninto the bodyTo get energyfrom food forthe cell to useThat’s right! The whole point of cellular respiration is to take the food you eat and make it into energy the cells can use.Since cells are so much smaller than the body, a cell couldn’t accomplish this.
3 What kind of energy is useful to cells? FoodATPFood is what cells break down to make the form of energy they can use.That’s right! Cells move energy from one part of the cell to another in the form of ATPWaterElectricitySorry, cells can’t get power from electricity!Cells do produce water – but it doesn’t give them energy
4 In cell respiration:A cell takes a molecule of food and breaks it apartBy breaking the bonds inside the food molecule, it releases energyIt uses this energy to make ATP moleculesWhich other parts of the cell can break open to get the energy for their own use
5 It’s a little like cooking… Not everybody wants to eat these rawBut anybody can get energy from theseClip art from Microsoft
6 It’s a little like cooking… Not all parts of your cell can get energy from the food you ateBut when that energy is packaged in ATP, all parts of the cell can use it
7 If taking energy out of the food molecules you ate and making ATP with it is like cooking, WHO ARE THE COOKS?The cooks are the enzymes that:Break down the food moleculesUse the energy to make ATPGet rid of the leftovers
8 Your cell has many groups of ‘cooks’ In a restaurant kitchen, you would have one area dealing with fish and another area dealing with pastry. Each area would have the expert cooks for that kind of food.Your cell, just like the restaurant, has different areas specialized to deal with different kinds of foods, with ‘expert’ enzymes in that area.
9 A major fuel for your cells is glucose HH-C-O-HCH-OH-C-O-HH-C-O-HCCH--O-HC6H12O6HH-O
10 Two sets of enzyme ‘cooks’ get energy from glucose The first set is out in the cell cytoplasm.As soon as glucose enters the cell, these enzymes grab it and chop it in half!Clip art from Microsoft
12 Breaking glucose in half takes some energy Breaking glucose in half takes some energy. The ‘chef’ uses 2 ATPs worth of energy to do the chopping.Clip art from Microsoft
13 It also produces some leftovers – Energy released!!But the chopping then releases enough energy to make 4 molecules of ATP. So there is a net gain of 2 ATPs from glycolysis.It also produces some leftovers –electrons that were removed from the glucose.
14 Two molecules of pyruvic acid (3 carbons each)One molecule of glucose(6 carbons)Energy released!! Net gain of 2 ATPsAND – 4 electrons are removed
15 Those electrons are a problem Electrons are dangerous to your cell.They can break other molecules, causing cell damage.So this ‘garbage’ has to beput in a safe place –an electron carrier.Clip art from Microsoft
16 Where will you put the electrons? Your cell has specialized molecules that act as electron carriersTheir names are NAD and FADEach carrier can carry 2electronsClip art from Microsoft
17 Two molecules of pyruvic acid (3 carbons each)One molecule of glucose(6 carbons)Energy released!! Net gain of 2 ATPsAND – 4 electrons are removedHanded to 2 molecules of NAD
18 But what will happen when all the NADs are filled? When the NADs are all filled, you willhave to stop doing glycolysis.Otherwise, your cell wouldstart to fill up with freeelectrons, and they woulddamage it.
20 What is the process of chopping glucose in half called? GlucogenesisGlycogenGluco- means glucoseBut ‘Genesis’ means ‘making’!Sorry – ‘glyco’ means glucose, but ‘gen’ means ‘maker’GlycolysisATP generationWhile breaking glucose can make ATP, there’s a special name for the process that tells what it does.Right! ‘Glyco’ means glucose and ‘lysis’ means ‘breaking’.Restart Quiz
22 What is the glucose chopped into? Two lamb chopsTwo pyruvic acidsVery funny…Right! One half of a glucose is a pyruvic acid.Two ATP moleculesTwo pairs of electronsSorry – the energy released by chopping the glucose gives a net gain of 2 ATP molecules.The electrons were pulled off when the bonds in theglucose were broken – but there was a lot more in the glucose than electrons.Restart Quiz
24 How many net ATPs did that make again? 26Right!That’s way too high – the process uses 2 ATPs and makes 4. So what’s the net gain?Sorry – the energy released by chopping the glucose makes 4 ATP, but you had to use 2 to do the chopping.48We wish! This is a lot more than you can get from glycolysis.Restart Quiz
26 And what were the ‘leftovers’ produced? Two lamb chopsTwo pyruvic acidsStill funny… not right, but funnyPyruvic acid is a byproduct, but it’s not a problem because your cell can eat it.Two ATP moleculesTwo pairs of electronsRight! These electrons are a potential problem for your cell.Hey! ATP’s what we WANTED to make, isn’t it? Not leftovers at all.Restart Quiz
28 Where will you put those electrons? They diffuse outof the cellIn the nucleusBAD, BAD idea. If you put them in the nucleus, they will damage the DNA and make the cell mutate.Not so much.Remember, the cell membrane is made of lipid. Polar things like electrons can’t diffuse across it.On the electroncarriersThat’s right!Nowhere, theyjust pile upThat’s going to cause a big problem for your cell…Restart Quiz
29 Some terminology …When the two pairs of electrons were taken off the glucose, the glucose was OXIDIZEDYou can remember thisby thinking of a lion, LEO:Loss of Electrons is Oxidation.Clip art from Microsoft
30 Some terminology …When the two pairs of electrons were handed to NAD molecules,the NAD molecules wereREDUCEDYou can remember thisby thinking of the lion growling, GER:Gain of Electrons is Reduction.Clip art from MicrosoftSound from Wavsource:Animals
31 When NAD is reduced, it becomes negatively charged Because electrons are negative, adding more of them to a molecule gives it a negative charge.This will make that molecule very attractive to positive ions like H+.
32 Hydrogen ions buzz around your cell like flies They follow electrons wherever they go, the way flies follow garbage.Clip art from Microsoft
33 So when electrons are handed to your NAD molecules, the H+ go too. When your NAD moleculesare full of electrons,they are alsofull of Hydrogen.
34 NADH + H+ In fact, many books write reduced NAD as to show that the Hydrogen ions are hanging around it.
35 Now, back to glycolysis!Your enzymes were working away, chopping glucose in half and making 2 ATP for every glucose they chopped.But then, all of the NAD electron carriers got full of electrons.The cell had to stop doing glycolysis, because it had no place to put the electrons.
36 This could kill your cell. If the cell can’t do glycolysis, it can’t make ATP!This is urgent – someone must TAKE OUT THE GARBAGE.
37 What can your cell do with all those electrons? Your cell has a very clever way of getting rid of the electrons so it can keep doing glycolysis.It puts them back on the pyruvic acids!
38 Two pyruvic acidsOne glucoseEnergy released!! Net gain of 2 ATPs2 electrons handed to each pyruvic acidAND – 4 electrons are removedHanded to 2 molecules of NAD, reducing them
40 When NAD hands its electrons to pyruvic acid, what happens? NAD is reducedNAD is oxidizedRemember GER: Gain of Electrons is Reduction.Did the NAD gain electrons?RIGHT!NAD has lost electrons, and Loss of Electrons is Oxidation.Pyruvic acidis oxidizedRemember LEO: Loss of Electrons is Oxidation.Did the pyruvic acid lose electrons?Glycolysis stopsNope! The whole point of handing off the electrons was to empty the NADs so glycolysis wouldn’t have to stop.Reset Question
41 Now the NAD is oxidized and can be used again! Glycolysis can go on! Two pyruvic acidsOne glucoseEnergy released!! Net gain of 2 ATPs2 electrons handed to each pyruvic acidAND – 4 electrons are removedHanded to 2 molecules of NAD, reducing themNow the NAD is oxidized and can be used again! Glycolysis can go on!
43 What’s happened to the pyruvic acid? It has beenreducedRight! Gain of Electrons is Reduction.The pyruvic acid gained 2 electrons and was reduced.It has been madeback into glucoseTo make glucose, you would have to stick those pyruvic acids back together.It has beenoxidizedRemember LEO: Loss of Electrons is Oxidation.Did the pyruvic acid lose electrons?It has beendestroyedNope! The molecule is still there, it just has two more electrons than it did before.Restart Questions
45 What will the H+ ions do? Stay with the NAD Go to the pyruvic acid Hydrogen ions follow electrons.Did the NAD gain or lose electrons?RIGHT!Those H+ will follow the electrons wherever they go.Die? How could you kill an ion?DieDiffuse out of the cellH+ are polar, and cannot diffuse across the cell membrane.Restart Questions
46 Pyruvic acid + 2 electrons + 2 H+ Lactic acidHave you heard of LACTIC ACID?It’s the stuff that makes your muscles burn when you exercise too hard.
48 Two pyruvic acidsMaking 2 LACTIC ACIDSOne glucoseEnergy released!! Net gain of 2 ATPs2 electrons handed to each pyruvicacidAND – 4 electrons are removedHanded to 2 molecules of NAD, reducing themNAD is re-oxidized
49 How will you get rid of the lactic acids? You know that after you exercise that hard, you sit down and pant.You’re doing that to get rid of the lactic acids and the electrons – but that’s another story, Metabolism part 2.You’re done with this tutorial – go back to the menu to try another.
50 ReferencesWavSource: Animals. Sound files for educational use. Retrieved April 3, 2007 from
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