Energy in the Cell Chapter 9
Cell Energy Energy is essential to life. All living organisms must be able to obtain energy from their environment Plants and green organisms trap sun’s energy Other organisms get energy from what they eat.
Work and Need for Energy Cell processes require energy: 1.active transport 2.cell division 3.movement of cilia and flagella 4.Production and storage of protein MOLECULE for Energy is ATP ATP stands for adenosine triphosphate
ATP ATP is quickly and easily used by the cell. Made of adenosine group and 3 phosphates- Phosphate groups are charged particles and have to be forced together. How is energy stored in ATP?
Forming and Breaking Down ATP Charged phosphate groups act like 2 positive poles of a magnet resisting each other. Requires ENERGY to bond 2 together, even more to bond 3 together. When the bond is BROKEN the energy is released. ATP becomes available to the cell when the molecule is broken down. AMP ADP ATP Monophosphatediphosphatetriphosphate
Breaking down and Building up ATP molecule is like a RECHARGABLE BATTERY To make A3P you add PHOSPHATE to A2P. To get energy from A3P you take a P away and are left with ADP (A2P). You can even get a SMALL amount of ENERGY from A2P by removing a Phosphate and making A1P (AMP). To store energy just load your ADP back up with more phosphate.
How cells tap into and store ATP When energy is released cells must be able to CAPTURE it efficiently. Many proteins have BINDING SITES for ATP. Works like a BATTERY. Nothing happens unless the battery is engaged. ATP is then RECHARGED by adding another Phosphate group.
CHAPTER 9 SECTION 3 C6H12O6 + 6O2 6 CO2 + 6 H2O Cellular Respiration CHAPTER 9 SECTION 3 C6H12O6 + 6O2 6 CO2 + 6 H2O
CELLULAR RESPIRATION Process by which cell breaks down food molecules to produce ATP. 3 stages Glycolysis (anaerobic) Citric Acid Cycle (aerobic) Electron Transport Chain (aerobic) **aerobic exercise is with OXYGEN *** anaerobic is WITHOUT oxygen.
Glycolysis (breaking glucose) Series of chemical reactions in the cytoplasm of a cell that break down glucose (6 carbons) into 2 molecules of PYRUVIC ACID. (3 carbons) Not very effective because it takes 2 molecules to start the process and only 4 are produced (Net of 2 ATP ) Following gycolysis the PYRUVIC ACID molecules move into the mitochondria, the organelle that transforms energy for the cell.
Glycolysis cont… Pyruvic acid moves across the membrane Outside of mitochondria inside of mitochondria O<>O Pyruvic acid moves across the membrane
IN THE PRESENCE OF OXYGEN Two more aerobic phases begin. CITRIC ACID CYCLE (aka KREB’s cycle) ELECTRON TRANSPORT CHAIN Without oxygen things will have to develop a back up survival plan.
Citric Acid Cycle Series of chemical reactions that start and begin with the same molecule (so it’s a cycle!) Acetyl Co A is the starting and ending molecule. For every turn of the cycle 1 molecule of ATP is produced and 2 molecules of CO2 per Pyruvic acid molecule. (2 ATP and 4 CO2 total) Following the cycle some excited NADH, FADH, and 3 H molecules drive excited electrons to an Electron Transport Chain….
Citric Acid Cycle (Acetyl-CoA) NAD+ Oxaloacetic acid Citric acid NADH + H+ NADH + H+ NAD+ (CO2) NAD+ NADH + H+ ADP + ATP FADH2 FAD
Electron Transport Chain Occurs in MITOCHONDRIAL membrane this time. Excited e- brought over by NADH and FADH2 are passed from protein to protein. Some energy is used to make ATP Some is used by an enzyme to pump H+ to the center of the mitochondria. Mitochondria inner membrane is positively charged with H+ ions while the outer membrane is negatively charged creating a concentration gradient providing energy for ATP production (just like photosynthesis)
ETC cont Final e- acceptor is OXYGEN. Which reacts with 4 H+ to make H2O. This is why oxygen is so important. Without oxygen the proteins canNOT pass off the final e- and everything STOPS. ETC produces 32 ATP molecules to the 4 already produced. Aerobic Respiration is very efficient. Total ATP production in Cell Respiration is 36.
Electron Transport Chain Electron carrier proteins Electron pathway 4H+ + O2 H2O NADH NAD+ ADP + + 4 electrons FADH2 FAD H2O
Anaerobic Respiration (without oxygen) Times when your cells are without oxygen for a short period of time such as heavy exercise, and anaerobic process begins this is called FERMENTATION. Fermentation will follow glycolysis to produce small amounts of ATP. 2 Types Lactic Acid Fermentation (2 ATP produced) Alcoholic Fermentation (2 ATP produced)
Lactic Acid Fermentation Electron Transport chain backs up because O2 is missing and carriers can’t release their e-. The 2 molecules of PYRUVIC ACID from glycolysis use NADH to form Lactic Acid this releases the NADH carrier again so it can be used again in glycolysis (FADH is stuck in the ETChain). Lactic Acid starts to build up in Muscle cells where it is being produced which causes muscle fatigue. Eventually it makes its way through the blood back to the liver where it is converted back into pyruvic acid.
Alcohol Fermentation Used by yeast cells and some bacteria to produce CO2 and ethyl alcohol. Mini lab p236