Cellular Respiration G 10 Team AISG

Why do we eat?

To acquire energy (and nutrients) but importantly, energy.

How do cells make energy (ATP)? ATP is the prime energy carrier for autotrophs and heterotrophs Fermentation and Anaerobic Respiration Release small amounts of energy Occurs in cytoplasm of cell WITHOUT O2 Aerobic Respiration Releases LARGE amounts of ATP Occurs in Mitochondrion of cell USES O2

What does ATP look like?

Why we need ATP: Types of cell work ATP is the fuel for cellular work. It fuels all the processes that make use considered “living”

Steps of Cellular Respiration: Glycolysis (Happens in all organisms in cytoplasm) (Link Reaction-links product of glycolysis to Krebs) Krebs Cycle (in the matrix of the mitochondria) Electron Transport Chain (in the inner membrane of mitochondria) Oxidative Phosphorylation/Chemiosmosis (the processes that result from the ETC) Oxidative phosphorylation: means oxygen needed (to accept used up electrons) when phosphate is added to ADP to make ATP Chemiosmosis means “chemical osmosis” so the movement of H+ from high to low concentration (intermembrane space back into matrix)

Cellular respiration is an organisms way to extract the chemical PE stored in the bonds in a slow and controlled manner, rather than the large explosive one like we saw with the gummy bear.

Substrate level phosphorylation means ATP made without use of an electron transport chain and ATP synthase

NADH made Link Rxn: CO2 given off

NADH Link Rxn: CO2 given off

Glycolysis: Glucose Splitting Glycolysis is a complicated process involving 10 separate chemical reactions but you just need to know …. It takes 2 ATP to start the process… so we invest 2 ATP at the beginning… and we get out: 4 ATP (for a net gain of 2 ATP) 2 NADH (e- carrier molecule!) A final product of 2 3-C pyruvate molecules

Remember: Glycolysis means “splitting glucose” A lot of chemical reactions happen to get from Glucose to Pyruvate Pyruvate is the final product of Glycolysis Pyruvate is a 3-Carbon Chain (We started with a 6- Carbon chain… known as glucose)

Pyruvate in the Link Reaction Pyruvate must be converted to acetyl CoA in order to enter the Kreb’s cycle Keys to remember: pyruvate converts to Acetyl CoA, while releasing CO2 and makiing more NADH

Krebs Cycle: Check it OUT: It can get really complicated, so we’ll try to keep it simple

Summary of Products Summary 2 Turns 3 CO2 for each turn 1 ATP for each turn 4 NADH for each turn 1 FADH2 for each turn 1 Acetyl CoA goes in and we make: 1 ATP, 4 NADH and 1 FADH2 (Yet another e-carrying molecule), from 1 glucose molecule, we have 2 Acetyl CoA so the cycle has to turn twice, resulting in : 2 ATP, 8 NASH and 2 FADH2 for each glucose

Electron Transport Chain and Phosphorylation (Fancy word for making ATP): Check it OUT (Looks a LOT like what happens in photosynthesis!)

Chemiosmosis couples with the ETC to make ATP Almost identical to the process in photosynthesis, the ETC is in the inner membrane of the mitochondria, where the electron comes from carriers NADH and FADH who drop of the energetic electron and an H+, the fall of the electron down the ETC, pumps the H+ across the inner membrane from the matrix INTO the intermembrane space where the H+ concentration builds up. H+ will flow down the concentration gradient from high concentration in the intermembrane space to low concentration in the matrix. It can only do this through the ATP syntase enzyme, which as you know by now is the enzyme that converts ADP and P into energetic ATP. So what happens to the electrons and H+ that are now in the matrix with no place to go….FINALLY we use oxygen. Oxygen to the rescue! O2 is the final electron acceptor and picks up both the electrons and H+ from the matrix and forms WATER!

ATP synthase (making ATP) Same exact process that happen in the chloroplast with the same enzyme and the same H+ concentration gradient…I KNOW so COOL!

Overview: Know This

Alcohol Fermentation (Anaerobic Respiration) Humans have used this ability in bacteria and yeasts for thousands of years to make wine, beer and raise bread!

Lactic Acid Fermentation Our bodies can turn to lactic acid fermentation for short periods of time, especially in our muscles when they are oxygen deprived, like during intense exercise. It is the production and build up of lactic acid in your muscles that make you sore the day after.

Pyruvate is the KEY Glycolysis WILL HAPPEN If O2 is present… cellular respiration! If O2 is NOT present, then fermentation happens (alcohol or lactic acid, it just depends on the organism) CHALLENGE: Why is it that only very small organisms can exist without oxygen at all?

Catabolism of various food molecules: Proteins Carbohydrates Fats

Compare Fermentation, Respiration and Photosynthesis

Fermentation Respiration Glycolysis Only Occurs in Cytoplasm 2 ATP Lactic Acid OR Ethanol Glycolysis, Krebs Cycle, ETC Cytoplasm and Mitochondria 36- 38 ATP CO2 AND H2O

Photosynthesis Respiration ATP formed by chemiosmosis Builds Glucose Makes some ATP Reactants: CO2 H2O Products: C6H12O6 O2 ATP formed by chemiosmosis Breaks down glucose Aerobic and Anaerobic make ATP Reactants: C6H12O6 O2 Products: CO2 H2O

Evolution of Energy Conversion Anaerobic Respiration Little ATP with NO O2 Small heterotrophic organisms Aerobic Respiration With O2 Lots of ATP Allowed for more work; thus size increased

Evolution of Energy Conversion Photosynthesis with PSI Made little ATP/uses Sun’s Energy no PSII, so no splitting H2O (cyclic electron transport) No Calvin Cycle-so no sugar Photosynthesis with PSII Made ATP with Sun’s Energy PS II (P680) enough energy to split H2O (release of O2) and non-cyclic electron transport Calvin Cycle- produced sugars