* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download ENERGY CURRENCY
Survey
Document related concepts
Electron transport chain wikipedia , lookup
Nicotinamide adenine dinucleotide wikipedia , lookup
Photosynthesis wikipedia , lookup
Epitranscriptome wikipedia , lookup
Microbial metabolism wikipedia , lookup
Basal metabolic rate wikipedia , lookup
Evolution of metal ions in biological systems wikipedia , lookup
Light-dependent reactions wikipedia , lookup
Photosynthetic reaction centre wikipedia , lookup
Biochemistry wikipedia , lookup
Citric acid cycle wikipedia , lookup
Transcript
ENERGY CURRENCY BEGINS Hello I’m Mr. Money. I’m here to inform you about ATP, the energy currency in the cell. You see, the cell operates a lot like a money system. Here are some comparisons: •In the money system the currency used is the dollar. How much work will you do for $1 $!0 $!00? It’s like a measurement of your energy! ATP- ADP + Pi + energy ADP + Pi + energy ATP •In the cell system the currency used is the ATP molecule. •The dollar could describe energy or work done to earn it and thus it represents stored energy. • ATP needs energy to assemble it and thus also represents stored energy.. •When a dollar is spent, it does not disappear, but rather is recycled and used over and over. • ATP, once used turns into the ADP molecule, but is reassembled back into ATP. It also is used over and over. •The dollar is the currency used throughout the country for all money transactions. •ATP is the energy molecule used by all eukaryote and prokaryote cells in all their cellular energy transactions. ATP is a short form representing the chemical Adenosine TriPhosphate. ATP is used in cells for the following work: Mechanical work – ex cilia beating, muscle contraction When exposed to the flame I turn blue green. You’ll find me on the adenine scene. Element Phosphate •Transport work – pumping substances across membranes •Chemical work – use of energy in biosynthesis of endergonic reactions Well, there it is, the ATP molecule. Notice it has three phosphate molecules. The bonds between these phosphates release energy when broken. The bonds between the phosphates are unstable and can be broken by hydrolysis. When water hydrolyzes the terminal phosphate bond, the molecule turns into ADP, phosphate Pi(inorganic) and -7.3 kcal of energy. This means ∆G = -7.3 kcal/mole for the following reaction (-ve means energy release) ATP + H2O ADP + Pi(inorganic) ATP bonds can release a lot of energy, but they actually are WEAK or UNSTABLE BONDS that are easily broken. Remember, each phosphate is negative, so each repels each other. ADP is thus more stable because it has less negative phosphates in the row repelling each other. I want you to notice something else about this molecule. Notice that it has three phosphates in a row with negative charges. These charges should naturally repel each other. Since they are together they store energy like a tightened spring So the high energy phosphate bond is actually not high because of a strong bond between phosphates, but rather high in energy because of the resultant release of energy due to hydrolysis of the terminal phosphate. Remember I taught you about exergonic and endergonic reactions! To the left, the diagram shows the ADP and Pi. This molecule can be reassembled back into ATP, but energy is required in order to do this. Thus an exergonic reactiion must first release energy. Catabolic pathways like cellular respiration provide this energy. Then the energy is used to power the endergonic reaction that ultimately makes the ATP molecule that stores energy. ADP + Pi + 7.3 kcal ATP + H2O ∆G = + 7.3 kcal/mol Photosynthesis can also use light energy to provide the energy necessary to make ATP. Hi there I’m ATP and I would like to inform you that I often can change due to the fact I can lose phosphates when I release ENERGY! If I lose one phosphate, I become ADP adenosine di phosphate. I often will cycle back to ATP in the energy exchange process and this is the most common usage. Cyclic AMP.......! I can also lose two phosphates and turn into AMP adenosine mono phosphate. Now this also can be cycled back to ATP, but there is a function of AMP. Specifically cAMP or cyclic AMP is involved in intercellular signalling, especially when you add adrenaline or glucagon to the body! Worm tackle fishing for info GETIT? I have a problem I want all you keen biology students to tackle. Glutamic acid plus ammonia can be converted into the amino acid glutamine. The change in free energy, your so called “Δ G “ is + 3.4 kcal /mol Can hydrolysis of ATP provide the energy to get this done? Not sure are you my courageous caped crusader crimefighter! You need genius me to walk you through it. Hydrolysis of ATP yields -7.3 kcal/mol Now I’ve given away the worm. You probably now can tell that if you couple these reactions you will... Have enough energy to produce the glutamine!! If you still don’t get it, think about how you need to provide 3.4 kcal/ mole of energy and the hydrolysis of ATP yields 7.4 kcal/mol. That’s more than enough energy to power the reaction! Before I move on I would like to introduce all of the energy molecules we will be dealing with. 1. ATP – PRIMARY ENERGY CURRENCY 2.NADH- Reduced form of NAD acts to store energy as it carries an electron. Used in cellular metabolism – is a coenzyme derived from vitamin B3 niacin 3.FADH2- Reduced form of FAD acts to store energy as it carries an electron. Used in cellular metabolism It is a coenzyme derived from vitamin B2 riboflavin 4.NADPH Reduced form of NADP acts to store energy as it carries an electron in photosynthesis. 5.GTP -- high energy molecule with phosphate bonds like those of ATP – can be changed into ATP. Hey girlie man. You better remember what I taught you or I will take your puny head with your little weak neck muscles and make the toilet seat your best friend! Glutamic acid is ionic electrically charged Glutamine is polar Now tell me this... is this glutamic acid polar ionic or non-polar? Don’t tell me you forget or you will suffer worse than Coli-for-ni-a. How about this one. What is this glutamine? Polar, ionic or non-polar? And yes you were supposed to memorize the chart that indicated this. You should not question the man of steel biceps!! Uh oh. Now I’ve done it! I have dropped you into freezing cold water! I can watch as your body attempt to maintain its temperature by the action of your muscles shivering!. Poor courageous caped crusader, you will be hydrolyzing ATP to generate heat. Each ATP will release it’s -7.3 kcal/mol into the surrounding tissues simply as heat. What a waste of energee! Rather inefficient use of the ATP wouldn’t you agree. But of course you can’t answer, you’re freezing to death by hypothermee!! Here’s a riddle for you now. What stage of hypothermia are you in. There are three, and if you pick correctly, you get to come out instantly! So you say stage 2. Well there’s your canoe! Riddle me this. What do ATP, DNA, and RNA share in common? They all contain ADENINE!! Both ATP and RNA contain adenine in form of Adenosine MonoPhosphate ( AMP is a nucleoside). ATP has an additional two phosphate groups added. ATP can be made in different ways. It can be made by substrate phosphorylation or it can be made by oxidative phosphorylation. In plants it is also made by photophosphorylaton This is an example of substrate level phosphorylation where ATP is made in the cytoplasm of cells with the aid of enzymes Photophosphorylation Oxidative generates ATP in the phosphorylation chloroplast of plant generates ATP via cells. chemiosmosis in the mitochondrion DID YOU KNOW? One muscle cell can consume and regenerate over 10,000,000 ATP's a second. If we did not regenerate and reuse ATP we would consume our body weight in ATP each day. ATP can release energy if hydrolyzed, but the energy can be more effectively captured by transferring a phosphate to some other molecule. This molecule is phosphorylated and is more unstable than the original molecule. The formation of phosphorylated intermediates is common in nearly all cellular work. Glutamic acid + Ammonia -Glutamine ∆G =+3.4 kcal/mol This reaction is non spontaneous because of the positive ∆G With the assistance of ATP and the formation of intermediates, this reaction can be made to occur spontaneously as shown by the net ∆G Glutamic acid + ATP Glutamic –P + ADP Glutamic—P + Ammonia Glutamine + P ∆G = + 3.4 kcal/mol ∆G = -7.3 kcal/mol Net ∆G = -3.9 kcal/mol Now I’d like you to meet NADH, another energy currency. NADH is worth 3 ATP , but in order for it to be utilized, it first must be converted into ATP. In order for this conversion to occur, oxidative pathways must be available. NAD+ is nicotinamide adenine dinucleotide and is found in all cells. It is actually classified as a coenzyme . In its reduced high energy form it is officially NADH + H+. (In this discussion, it will be understood that NADH represents NADH + H+.) NAD+ acts as an oxidizing agent and can remove a pair of electrons (and protons H+) from a substrate. These two electrons along with one proton attach to the NAD+ to form NADH. The other proton is released as a hydrogen ion (H+) forming NADH + H+. An example of this is shown below where X represents the substrate that is oxidized. XH2 + NAD+ -- X + NADH + H+. Now I’d like you to meet FADH2. FADH2 is only worth 2 ATP , but in order for it to be utilized, it first must be converted into ATP. In order for this conversion to occur, oxidative pathways must be available. FAD is flavin adenine dinucleotide which is a coenzyme in metabolic pathways. The FAD is used as an oxidizing agent and will accept two hydrogen atoms from a substrate to produce the high energy FADH2. An example of this is shown below where X represents the substrate that is oxidized. XH2 + FAD -- X + FADH2. FAD actually only has one nucleotide even though the name says dinucleotide. Who would have thought? FAD is derived from vitamin B2 Riboflavin - there’s the flavin. I’m just flavin like flavor flav Here are the two main methods of generating the ATP molecule. SUBSTRATE LEVEL PHOSPHORYLATION OF ATP ATP can be generated by substrate level phosphorylation. You can see the enzyme action and the assemble of the ATP molecule shown on the side. All cells are capable of this type of ATP synthesis. CHEMIOSMOSIS GENERATION OF ATP ATP can also be generated by a protein membrane complex coupled to the ATP synthase. Hydrogen ions are locked in a membrane and as they attempt to reach equal numbers both inside and outside OSMOSIS they pass through ATP synthase and generate ATP from ADP and Pi. Another energy molecule is NADPH. This is simply a variant on NADH where phosphate has been added. It is restricted to use in the photosynthetic pathways . NADP+ is nicotinamide adenine dinucleotide phosphate and is reduced into the higher energy NADPH. NADPH is used in biosynthesis of organic molecules in the Calvin cycle. Not the Pontiac GTP! GTP is another energy molecule and it is similar to ATP. It utilizes the nitrogen base guanine rather than adenine, but otherwise the molecule is basically the same. It has the same three phosphates attached that produce the high energy phosphates bonds which when hydrolyzed. I’m Dr. Krebs. You’ll see my cycle soon! Translation of proteins from RNA GTP can be converted into ATP (This is done in the Krebs cycle) GTP is used specifically in protein synthesis as an energy source. It acts like ATP, but is more specific. GTP is essential to signal conduction inside of cells where it acts as a second messenger to cause the activation of metabolic pathways. GTP converts to GDP+ Pi much the same as the ATP hydrolysis reaction. Riddle me this or you lose Mr. Money! I once had a charge, but now I am neutral. I’ve gained two e’s but just one p. What am I? I’m NADH I disguise as Dan only inverse and I don’t leave home without my sceptre. I am your green solution, just like environmentalists adore. Just Try to figure out who I am. You’ll never see me take out an AD....... I’m NADPH I’m ATP Time for me to take away the MONEY. Mr. Money is mine now! HELP!! Hi there. Remember me, I’m the ATP molecule. I want you to slow down for a minute and ponder something special. I want you to look at the big picture of these energy molecules. You see, they all seem to have something in common. They all have purine ( Adenine or guanine) nitrogen bases attached to sugars and phosphates. You might just think this is some sort of coincidence, but maybe it is not. Maybe it relates to a much bigger concept. The metabolic pathways we will study are common to virtually all living things. This connects all life on the planet together......together to a common ancestral origin. Why is there this common thread of the chemicals of metabolism?...I submit the answer is evolution. The creation of the first living cells! I have discovered the secret. I have CREATED LIFE!!!! Come see me as soon as you can in my presentation of the first cells. I guarantee you will understand so much more about our world!! Now I understand that your background in evolution may not be very strong, so bear with me. Evolution is integral to understanding the living things we see today and understanding how they came to be. Lets take a look again at our energy molecules. ATP and NADH are present in all known forms of life forming a core part of metabolism and indicating that these molecules evolved very early in the development of living things At least some of the current set of cofactors may therefore have been present in an ancestor , that lived about 4 billion years ago. ( The earth was formed 4.5 billion years ago) Now here is the leap. Evidence seems to point to these molecules pre-dating even the first cells. The Theory that is gaining support is that of the RNA world. The RNA molecule can act as both an enzyme and an information molecule. RNA in this theory predates the DNA directed living world we see today. The RNA evolved into the more stable DNA world of today, but the remnants of these early pathways persist in all our cells. Take it away Inspector Clouseau. Facts, students, facts! Nothing matters but the facts. Without them the science of investigation is nothing more than a guessing game. Facts, dear students, facts, behind them lays the whole fabric of deductive truth. Now, students let us examine these facts: 1 1. FACT ---the nucleotide ADENOSINE is present in cofactors that catalyze many basic metabolic reactions such as methyl, acyl, and phosphoryl group transfer, as well as REDOX reactions.ie ATP NADH FADH2... 2. FACT –nucleotide ADENOSINE is the building block to assemble the RNA informational molecular chain, it has the nitrogen base, sugar, and phosphate in the correct bonding arrangement. 3. FACT – RNA can act to catalyze a chemical reaction -- called a ribozyme Now then, Mr. ATP , tell the students what these facts add up to? 4. FACT--- in ribosomes (made of RNA +protein) the RNA adenosine site is the active site (not the protein) that catalyzes the peptide bonds to make amino acid chains( proteins). RNA here is a ribozyme 5.FACT—RNA can catalyze its own synthesis – it can make itself from chemical reactions it catalyzes. Well those facts seem to point to the RNA as being the earliest information storing molecules that most likely were also capable of generating the first protein molecules. These are the basic tasks of the DNA molecule of today. But the facts?? ?????? ????? You are an idiot, only a fresh faced novice would come up with a conclusion like that. Listen, you are forgetting the most important fact– instinct My instinct tells me that the molecule that started all this is still not settled. What is happening here is an attempt to lay the blame at the foot of this, this poor RNA molecule. Inspector, the RNA world hypothesis places RNA at center-stage when life originated. This has been accompanied by many studies in the last ten years demonstrating important aspects of RNA function that were not previously known, and support the idea of a critical role for RNA in the functionality of life. You will also want to know that we have located the Riddler. I arrest you in the name of the leahw! So that’s the way it’s gonna be! Purine metabolism molecules surrounding me!! You think that can stop me? I think NOT! NAD It’s over Riddler! Don’t make me have to reduce myself to NADPH ! NADP That’s right, my reduced form FADH2 has very high energy! Hey, he is so witty. We all have purine bases. What a waste of intelligence. GTP ATP You don’t want to see me when I am reduced to NADH! FAD Lets take this walking green piece of scum to jail boys! Good work my little crimefighturs. I’m innocent. I didn’t do nothin’. You can’t prove I did nothin’!! Did you say Crime fighturs? That’s wrong, it’s crime fighters. That is what I said you ignorant jail-bird. My crime-fighturs have captur-ed you! He is one to talk with his slang usage of the language. Hey thanks for the rescue. See you soon! End Energy Molecules