Conversion of glucose to ATP

 1. Overview  2. Purpose: To Get ATP!  3. Electron Carrier Molecules  4. Mitochondria  5. The Basics of Cell Respiration  6. Glycolysis  7.Pyruvate chemical “grooming”  8. Kreb’s Cycle  9. Electron Transport Chain (Oxidative Phosphorylation)  10. Cell Respiration Summary  11. Fermentation- Anaerobic Respiration

Who does it? All living things: both autotrophs and heterotrophs What is it? Carbohydrates and O 2 are used to make ATP (energy). CO 2 and H 2 0 are waste products. Involves three steps: glycolysis, kreb’s cycle, and electron transport chain. The opposite of photosynthesis. Where does it occur? The cytoplasm and the mitochondria of the cell

 Cellular respiration releases energy by breaking down glucose and other food molecules in the presence of oxygen.  Equation:  C 6 H 12 O 6 + 6O 2  6CO 2 + 6H ATP  Glucose+ oxygen  carbon dioxide + water + energy

 ATP: A modified nucleotide molecule that powers all cellular work directly.

 Phosphorylation  When ATP releases a phosphate + energy it produces ADP (adenosine diphosphate)  ADP can turn back to ATP by taking in a phosphate and energy by phosphorylation  Similar to recharging a battery

 There are two different molecules that are used to carry electrons and hydrogen ions to the last step cellular respiration.  NADH- NAD+  FADH2- FAD

 Cellular respiration takes place in small steps to minimize the loss of energy in the form of heat or light.  Processes that require oxygen to take place are called aerobic.  Processes that do not require oxygen to take place are anaerobic.

 Aerobic Cellular respiration consists of three major steps (when oxygen is present):  Glycolysis – occurs in the cytoplasm  The Krebs cycle – occurs in the matrix of mitochondrion  Electron transport chain – occurs along the innermembrane in the cristae of mitochondrion

 Means “splitting sugar”  Occurs in the cytoplasm  Is anaerobic (doesn’t require oxygen)  Glucose (6-C) is split to two molecules of another organic compound, called pyruvate (3- C).  Makes 4 ATP, but uses 2 ATP, for a net gain of 2 ATP  ATP can be used by cell immediately  A net gain of 2 NADH molecules  NADH must pass down the ETC in mitochondria  Water is released as waste product

 As pyruvate forms at the end of glycolysis, it is transported from the cytoplasm into the mitochondria  Pyruvate does not enter the Kreb’s Cycle as itself.  It undergoes major chemical “grooming”

 A carbon atom is removed from pyruvate (3-C) forming acetyl coA (2-C)  NADH molecules are made (per pyruvate-3C)  CO2 is released as a waste product (per pyruvate-3C)

 Occurs in the matrix of the mitochondria  Compared with glycolysis, Kreb’s Cycle pays big energy dividends to the cell  This makes 1 ATP, 3 NADH and 1 FADH 2, per acetyl coA (2-C) (double that for each glucose molecule)  Releases CO 2 as waste  is aerobic (requires oxygen)

 Occurs along the inner membrane of the cristae of the mitochondria  NADH and FADH2 from glycolysis and Kreb’s Cycle give up their H+ and electrons to make ATP  3 ATP for each NADH and 2 ATP for each FADH2  O2 is the final electron acceptor and becomes water which is a waste product  Is aerobic and makes most of the energy in cell respiration.

 TOTAL= 38 ATP (theoretical)  Glycolysis  Occurs in cytoplasm  2 ATP  2 NADH  2 H20 get released  2 pyruvate  Kreb’s Cycle (including pyruvate grooming)  2 ATP  8 NADH  2 FADH2  6 CO2 get released  Electron Transport Chain  H20 gets released  10 NADH get converted to 3ATP= 30 ATP  2 FADH2 get converted to 2 ATP= 4 ATP

 Glycolysis is the metabolic pathway that generates ATP during fermentation.  No O 2 is required; it generates a net gain of 2 ATP and 2 NADH  Significantly less ATP is generated, but it is enough to keep your muscles contracting for a short while when the need for ATP outpaces the delivery of O2 via the blood stream  Many microorganisms supply all their energy needs with the 2 ATP yield of glycolysis.

 Fermentation provides an anaerobic step that recycles NADH back to NAD+; essential to harvest food energy by glycolysis.  Two types of fermentation:  Lactic acid  Alcohol

 Lactic acid fermentation  1. Glycolysis occurs  2. NADH is recycled to NAD+ as pyruvate becomes to lactic acid.  Lactate builds up in muscle cells during strenuous exercise is carried in the blood to the liver, where it is converted back to pyruvate  Dairy industry use this to with bacteria to make cheese and yogurt

 Alcohol fermentation  1. Glycolysis occurs  2. NADH is recycled to NAD+ while pyruvate (3-C) releases a CO2 and becomes ethanol (2-C) (ethyl alcohol).  Used by yeasts and bacteria  Used in brewing, winemaking, and baking  CO2 provides bubbles in beer and champagne, and bread dough to rise  Ethanol is toxic to organisms that produce it; must release it to their surroundings