Making energy! ATP The point is to make ATP!.

Making energy! ATP The point is to make ATP!

First Law Of Thermodynamics Figure 8.3 Chemical energy (a)
First law of thermodynamics: Energy can be transferred or transformed but Neither created nor destroyed. For example, the chemical (potential) energy in food will be converted to the kinetic energy of the cheetah’s movement in (b). (a) Chemical energy First Law Of Thermodynamics

Second Law + Figure 8.3 Heat co2 H2O (b)
Second law of thermodynamics: Every energy transfer or transformation increases the disorder (entropy) of the universe. For example, disorder is added to the cheetah’s surroundings in the form of heat and the small molecules that are the by-products of metabolism. (b) Heat co2 H2O + Second Law

Free Energy

Reactions in a Closed System:
∆G < 0 ∆G = 0 What would happen To a living System if it were closed?

Body Cells: ∆G < 0 What do we Need to Stay alive?

The energy needs of life
Organisms are endergonic systems What do we need energy for? synthesis building biomolecules reproduction movement active transport temperature regulation Which is to say… if you don’t eat, you die… because you run out of energy. The 2nd Law of Thermodynamics takes over!

Where do we get the energy from?
Work of life is done by energy coupling use exergonic (catabolic) reactions to fuel endergonic (anabolic) reactions digestion energy + + synthesis energy + +

Build once, use many ways
ATP Adenosine TriPhosphate modified nucleotide nucleotide = adenine + ribose + Pi  AMP AMP + Pi  ADP ADP + Pi  ATP adding phosphates is endergonic Marvel at the efficiency of biological systems! Build once = re-use over and over again. Start with a nucleotide and add phosphates to it to make this high energy molecule that drives the work of life. Let’s look at this molecule closer. Think about putting that Pi on the adenosine-ribose ==> EXERGONIC or ENDERGONIC? How efficient! Build once, use many ways high energy bonds

How does ATP store energy?
I think he’s a bit unstable… don’t you? How does ATP store energy? P O– O –O P O– O –O P O– O –O P O– O –O P O– O –O ADP AMP ATP Each negative PO4 more difficult to add Not a happy molecule Add 1st Pi  Kerplunk! Big negatively charged functional group Add 2nd Pi  EASY or DIFFICULT to add? DIFFICULT takes energy to add = same charges repel  Is it STABLE or UNSTABLE? UNSTABLE = 2 negatively charged functional groups not strongly bonded to each other So if it releases Pi  releases ENERGY Add 3rd Pi  MORE or LESS UNSTABLE? MORE = like an unstable currency • Hot stuff! • Doesn’t stick around • Can’t store it up • Dangerous to store = wants to give its Pi to anything Instability of its P bonds makes ATP an excellent energy donor

How does ATP transfer energy?
+ ATP ADP ATP  ADP releases energy ∆G = -7.3 kcal/mole Fuel other reactions Phosphorylation released Pi can transfer to other molecules destabilizing the other molecules enzyme that phosphorylates = “kinase” How does ATP transfer energy? By phosphorylating Think of the 3rd Pi as the bad boyfriend ATP tries to dump off on someone else = phosphorylating How does phosphorylating provide energy? Pi is very electronegative. Got lots of OXYGEN!! OXYGEN is very electronegative. Steals e’s from other atoms in the molecule it is bonded to. As e’s fall to electronegative atom, they release energy. Makes the other molecule “unhappy” = unstable. Starts looking for a better partner to bond to. Pi is again the bad boyfriend you want to dump. You’ve got to find someone else to give him away to. You give him away and then bond with someone new that makes you happier (monomers get together). Eventually the bad boyfriend gets dumped and goes off alone into the cytoplasm as a free agent = free Pi.

An example of Phosphorylation…
Building polymers from monomers need to destabilize the monomers phosphorylate! H OH C H HO C enzyme C H OH HO O + H2O synthesis +4.2 kcal/mol + ADP C H OH “kinase” enzyme C H P Monomers  polymers Not that simple! H2O doesn’t just come off on its own You have to pull it off by phosphorylating monomers. Polymerization reactions (dehydration synthesis) involve a phosphorylation step! Where does the Pi come from? ATP It’s never that simple! + ATP -7.3 kcal/mol C H P H HO C + C H O + Pi -3.1 kcal/mol

Cells spend a lot of time making ATP!
The point is to make ATP! What’s the point?

How is ATP Made in a Cell? Substrate Level Phosphorylation

Start with a mitochondrion or chloroplast
Chemiosmosis Start with a mitochondrion or chloroplast Trap H+ in the intermembrane space

Start with a mitochondrion or chloroplast
Chemiosmosis Start with a mitochondrion or chloroplast Trap H+ in the intermembrane space How can this lead to ATP production?

But… How is the proton (H+) gradient formed?
catalytic head rod rotor ATP synthase Enzyme channel in mitochondrial membrane permeable to H+ H+ flow down concentration gradient flow like water over water wheel flowing H+ cause change in shape of ATP synthase enzyme powers bonding of Pi to ADP: ADP + Pi  ATP ADP P + ATP But… How is the proton (H+) gradient formed?

That’s the rest of my story!
Any Questions?

Cellular Respiration Harvesting Chemical Energy
ATP

What’s the point? The point is to make ATP! ATP

Harvesting stored energy
Energy is stored in organic molecules carbohydrates, fats, proteins Heterotrophs eat these organic molecules  food We eat to take in the fuels to make ATP which will then be used to help us build biomolecules and grow and move and… live! heterotrophs = “fed by others” vs. autotrophs = “self-feeders”

Harvesting stored energy
Which releases more Energy, combustion Of glucose or Cellular respiration? Harvesting stored energy glucose + oxygen  energy + water + carbon dioxide respiration + heat C6H12O6 6O2 ATP 6H2O 6CO2  + Movement of hydrogen atoms from glucose to water fuel (carbohydrates) COMBUSTION = making a lot of heat energy by burning fuels in one step RESPIRATION = making ATP (& some heat) by burning fuels in many small steps ATP ATP glucose enzymes O2 O2 CO2 + H2O + heat CO2 + H2O + ATP (+ heat)

How do we harvest energy from fuels?
Oxidation Reduction • They are called oxidation reactions because it reflects the fact that in biological systems oxygen, which attracts electrons strongly, is the most common electron acceptor. • Oxidation & reduction reactions always occur together therefore they are referred to as “redox reactions”. • As electrons move from one atom to another they move farther away from the nucleus of the atom and therefore are at a higher potential energy state. The reduced form of a molecule has a higher level of energy than the oxidized form of a molecule. • The ability to store energy in molecules by transferring electrons to them is called reducing power, and is a basic property of living systems. loses e- gains e- oxidized reduced + – + e- e- e- oxidation reduction redox

How do we move electrons in biology?
Moving electrons in living systems electrons cannot move alone in cells electrons move as part of H atom move H = move electrons p e + H – loses e- gains e- oxidized reduced oxidation reduction Energy is transferred from one molecule to another via redox reactions. C6H12O6 has been oxidized fully == each of the carbons (C) has been cleaved off and all of the hydrogens (H) have been stripped off & transferred to oxygen (O) — the most electronegative atom in living systems. This converts O2 into H2O as it is reduced. The reduced form of a molecule has a higher energy state than the oxidized form. The ability of organisms to store energy in molecules by transferring electrons to them is referred to as reducing power. The reduced form of a molecule in a biological system is the molecule which has gained a H atom, hence NAD+  NADH once reduced. soon we will meet the electron carriers NAD & FADH = when they are reduced they now have energy stored in them that can be used to do work. C6H12O6 6O2 6CO2 6H2O ATP  + oxidation H reduction e-

Moving electrons in respiration
like $$ in the bank Moving electrons in respiration Electron carriers move mighty electrons by shuttling H atoms around NAD+  NADH (reduced) FAD+2  FADH2 (reduced) reducing power! P O– O –O C NH2 N+ H adenine ribose sugar phosphates NAD+ nicotinamide Vitamin B3 niacin NADH P O– O –O C NH2 N+ H H How efficient! Build once, use many ways + H reduction Nicotinamide adenine dinucleotide (NAD) — and its relative nicotinamide adenine dinucleotide phosphate (NADP) which you will meet in photosynthesis — are two of the most important coenzymes in the cell. In cells, most oxidations are accomplished by the removal of hydrogen atoms. Both of these coenzymes play crucial roles in this. Nicotinamide is also known as Vitamin B3 is believed to cause improvements in energy production due to its role as a precursor of NAD (nicotinamide adenosine dinucleotide), an important molecule involved in energy metabolism. Increasing nicotinamide concentrations increase the available NAD molecules that can take part in energy metabolism, thus increasing the amount of energy available in the cell. Vitamin B3 can be found in various meats, peanuts, and sunflower seeds. Nicotinamide is the biologically active form of niacin (also known as nicotinic acid). FAD is built from riboflavin — also known as Vitamin B2. Riboflavin is a water-soluble vitamin that is found naturally in organ meats (liver, kidney, and heart) and certain plants such as almonds, mushrooms, whole grain, soybeans, and green leafy vegetables. FAD is a coenzyme critical for the metabolism of carbohydrates, fats, and proteins into energy. oxidation carries electrons as a reduced molecule

Overview of cellular respiration
4 metabolic stages Anaerobic respiration 1. Glycolysis respiration without O2 in cytosol Aerobic respiration respiration using O2 in mitochondria 2. Pyruvate oxidation 3. Krebs cycle 4. Electron transport chain C6H12O6 6O2 ATP 6H2O 6CO2  + (+ heat)

Cellular Respiration Stage 1: Glycolysis

In the cytosol? Why does that make evolutionary sense?
Glycolysis Breaking down glucose “glyco – lysis” (splitting sugar) but it’s inefficient generate only 2 ATP for every 1 glucose still is starting point for ALL cellular respiration occurs in cytosol In the cytosol? Why does that make evolutionary sense? glucose      pyruvate 2x 6C 3C Why does it make sense that this happens in the cytosol? Who evolved first? That’s not enough ATP for me

Evolutionary perspective
Enzymes of glycolysis are “well-conserved” Prokaryotes first cells had no organelles Anaerobic atmosphere life on Earth first evolved without free oxygen (O2) in atmosphere Prokaryotes that evolved glycolysis are ancestors of all modern life ALL cells still utilize glycolysis The enzymes of glycolysis are very similar among all organisms. The genes that code for them are highly conserved. They are a good measure for evolutionary studies. Compare eukaryotes, bacteria & archaea using glycolysis enzymes. Bacteria = 3.5 billion years ago glycolysis in cytosol = doesn’t require a membrane-bound organelle O2 = 2.7 billion years ago photosynthetic bacteria / proto-blue-green algae Eukaryotes = 1.5 billion years ago membrane-bound organelles! Processes that all life/organisms share: Protein synthesis Glycolysis DNA replication You mean we’re related? Do I have to invite them over for the holidays?

Overview 10 reactions glucose C-C-C-C-C-C fructose-1,6bP
ATP 2 enzyme 10 reactions ADP 2 enzyme fructose-1,6bP P-C-C-C-C-C-C-P enzyme enzyme enzyme What has more Free energy, G3P or pyruvate? DHAP P-C-C-C G3P C-C-C-P NAD+ 2 2H 2Pi 1st ATP used is like a match to light a fire… initiation energy / activation energy. Destabilizes glucose enough to split it in two enzyme 2 enzyme ADP 4 2Pi enzyme ATP 4 pyruvate C-C-C

Glycolysis summary -2 ATP 4 ATP endergonic invest some ATP exergonic
ENERGY INVESTMENT -2 ATP G3P C-C-C-P exergonic harvest a little ATP & a little NADH ENERGY PAYOFF 4 ATP Glucose is a stable molecule it needs an activation energy to break it apart. phosphorylate it = Pi comes from ATP. make NADH & put it in the bank for later. like $$ in the bank net yield 2 ATP 2 NADH NET YIELD

Substrate-level Phosphorylation
In the last steps of glycolysis, where did the P come from to make ATP? the sugar substrate (PEP) H2O 9 10 Phosphoenolpyruvate (PEP) Pyruvate enolase pyruvate kinase ADP ATP CH3 O- O C P CH2 P is transferred from PEP to ADP kinase enzyme ADP  ATP ATP What sort of Enzyme does This?

Energy accounting of glycolysis
2 ATP 2 ADP glucose      pyruvate 6C 2x 3C 4 ADP ATP 4 The magic number is? 2 NAD+ 2 And that’s how life subsisted for a billion years. Until a certain bacteria ”learned” how to metabolize O2; which was previously a poison. But now pyruvate is not the end of the process Pyruvate still has a lot of energy in it that has not been captured. It still has 3 carbons bonded together! There is still energy stored in those bonds. It can still be oxidized further. Where is the Extra energy? Net gain = 2 ATP + 2 NADH some energy investment (-2 ATP) small energy return (4 ATP + 2 NADH) 1 6C sugar  2 3C sugars

Hard way to make a living!
Is that all there is? Not a lot of energy… for 1 billon years+ this is how life on Earth survived no O2 = slow growth, slow reproduction only harvest 3.5% of energy stored in glucose more carbons to strip off = more energy to harvest O2 glucose     pyruvate O2 So why does glycolysis still take place? 6C 2x 3C O2 Hard way to make a living! O2 O2

raw materials  products
But can’t stop there! Pi NAD+ G3P 1,3-BPG NADH DHAP 7 8 H2O 9 10 ADP ATP 3-Phosphoglycerate (3PG) 2-Phosphoglycerate (2PG) Phosphoenolpyruvate (PEP) Pyruvate NAD+ NADH Pi 6 raw materials  products Glycolysis glucose + 2ADP + 2Pi + 2 NAD+  2 pyruvate + 2ATP + 2NADH Going to run out of NAD+ without regenerating NAD+, energy production would stop! another molecule must accept H from NADH so NAD+ is freed up for another round What is the Oxidizing Agent of Glycolysis?

How is NADH recycled to NAD+?
with oxygen aerobic respiration without oxygen anaerobic respiration “fermentation” Another molecule must accept the mighty electrons from NADH pyruvate H2O NAD+ CO2 recycle NADH NADH O2 NADH acetaldehyde acetyl-CoA NADH NAD+ What has more Free energy Pyruvate or Lactic acid? NAD+ lactate lactic acid fermentation Krebs cycle ethanol alcohol fermentation

Fermentation (anaerobic)
Bacteria, yeast 1C 3C 2C pyruvate  ethanol + CO2 NADH NAD+ back to glycolysis beer, wine, bread Animals, some fungi Count the carbons!! Lactic acid is not a dead end like ethanol. Once you have O2 again, lactate is converted back to pyruvate by the liver and fed to the Kreb’s cycle. pyruvate  lactic acid 3C NADH NAD+ back to glycolysis cheese, anaerobic exercise (no O2)

Pyruvate is a branching point
fermentation anaerobic respiration mitochondria Krebs cycle aerobic respiration

pyruvate    acetyl CoA + CO2
Oxidation of pyruvate Pyruvate enters mitochondrial matrix 3 step oxidation process releases 2 CO2 (count the carbons!) reduces 2 NAD  2 NADH (moves e-) produces 2 acetyl CoA Acetyl CoA enters Krebs cycle [ 2x ] pyruvate    acetyl CoA + CO2 3C NAD 2C 1C Where does the CO2 go? Exhale! CO2 is fully oxidized carbon == can’t get any more energy out it CH4 is a fully reduced carbon == good fuel!!!

Krebs cycle 1937 | 1953 aka Citric Acid Cycle
in mitochondrial matrix 8 step pathway each catalyzed by specific enzyme step-wise catabolism of 6C citrate molecule Evolved later than glycolysis does that make evolutionary sense? bacteria 3.5 billion years ago (glycolysis) free O2 2.7 billion years ago (photosynthesis) eukaryotes 1.5 billion years ago (aerobic respiration = organelles  mitochondria) Hans Krebs The enzymes of glycolysis are very similar among all organisms. The genes that code for them are highly conserved. They are a good measure for evolutionary studies. Compare eukaryotes, bacteria & archaea using glycolysis enzymes. Bacteria = 3.5 billion years ago glycolysis in cytosol = doesn’t require a membrane-bound organelle O2 = 2.7 billion years ago photosynthetic bacteria / proto-blue-green algae Eukaryotes = 1.5 billion years ago membrane-bound organelles! Processes that all life/organisms share: Protein synthesis Glycolysis DNA replication

Count the carbons! x2 3C 2C 4C 6C 4C 6C 5C 4C 4C 4C
pyruvate 3C 2C acetyl CoA citrate 4C 6C 4C 6C This happens twice for each glucose molecule oxidation of sugars CO2 A 2 carbon sugar went into the Krebs cycle and was taken apart completely. Two CO2 molecules were produced from that 2 carbon sugar. Glucose has now been fully oxidized! But where’s all the ATP??? x2 5C 4C CO2 4C 4C

reduction of electron carriers
Count the electron carriers! CO2 pyruvate 3C 2C acetyl CoA NADH NADH citrate 4C 6C 4C 6C reduction of electron carriers This happens twice for each glucose molecule CO2 Everytime the carbons are oxidized, an NAD+ is being reduced. But wait…where’s all the ATP?? NADH x2 5C 4C FADH2 CO2 4C 4C NADH ATP

Whassup? So we fully oxidized glucose C6H12O6  CO2
& ended up with 4 ATP! What’s the point?

What’s so important about electron carriers?
Electron Carriers = Hydrogen Carriers H+ Krebs cycle produces large quantities of electron carriers NADH FADH2 go to Electron Transport Chain! ADP + Pi ATP What’s so important about electron carriers?

Energy accounting of Krebs cycle
2x 4 NAD + 1 FAD 4 NADH + 1 FADH2 pyruvate          CO2 1 ADP 1 ATP 3C 3x 1C ATP Net gain = 2 ATP = 8 NADH + 2 FADH2

Value of Krebs cycle? If the yield is only 2 ATP then how was the Krebs cycle an adaptation? value of NADH & FADH2 electron carriers & H carriers reduced molecules move electrons reduced molecules move H+ ions to be used in the Electron Transport Chain like $$ in the bank

Where is all of the energy after glycolysis and citric acid cycle?
It is in the 4 ATP’s that were made But where is the rest of the energy? It is in the NADH and FADH2’s Time to break open the piggybank! Where can these Electrons go?

Now it’s time for chemiosmosis
So far the ATP’s have been generated via substrate level phosphorylation Now it’s time for chemiosmosis Where is the energy Coming from for the active transport? ???

What pulls electrons out of the chain?
What happens to the energy that is lost from the electrons? AHH, the active transport!

Peter Mitchell 1961 | 1978 Proposed chemiosmotic hypothesis
revolutionary idea at the time

ATP Pyruvate from cytoplasm Intermembrane space Inner mitochondrial
Electron transport system C Q NADH e- 2. Electrons provide energy to pump protons across the membrane. H+ 1. Electrons are harvested and carried to the transport system. e- Acetyl-CoA NADH e- H2O Krebs cycle e- 3. Oxygen joins with protons to form water. 1 FADH2 O2 2 O2 + 2H+ CO2 H+ ATP ATP H+ ATP 4. Protons diffuse back in down their concentration gradient, driving the synthesis of ATP. ATP synthase Mitochondrial matrix

How are 34 ATPs made

Variables in ATP yield:
Some mitochondria differ in permeability to protons, which effects the proton motive force. Proton motive force may be directed to drive other cellular processes such as active transport. ATP yield is inflated by rounding up Prokaryotic cellular respiration is slightly higher since no mitochondrial membrane used to transport electrons from NADH.

How do we use food other than glucose to generate energy?

Making energy! ATP The point is to make ATP!.

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Making energy! ATP The point is to make ATP!.

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