Cellular Respiration
Unit III
Chapter 9
Flash Cards Due Tomorrow
Respiration
Next 3 should have (what they do, where they occur, and what they produce)
Glycolysis Krebs Cycle Electron Transport Pyruvate Aerobic Respiration Anaerobic Respiration Fermentation
Overview of Cellular Respiration
Cellular respiration is the process that releases energy by breaking down food molecules in the presence of oxygen Organisms that respire: animals, fungi, plants
(during night hours) Cellular respiration requires a food molecule
(such as glucose), oxygen, and it gives off carbon dioxide
Because is occurs in the PRESENCE of OXYGEN, cellular respiration is known as AEROBIC respiration
Chemical Formula for Cellular Respiration The chemical formula for cellular respiration
is: 6O2 + C6H12O6 → 6 CO2 + 6 H2O +
Energy oxygen + glucose → carbon dioxide +
water + energy The reactants of cellular respiration are:
oxygen (O2) & glucose (C6H12O6) The products of cellular respiration are:
carbon dioxide (CO2) and water (H2O)
The 3 main stages of cellular respiration are:
1. Glycolysis
1. Krebs Cycle (Citric Acid Cycle)
1. Electron Transport
Visual Overview of Cellular Respiration
Krebs
Cycle
Glycolysis
The first set of reactions in cellular respiration is glycolysis Glycolysis is the process in which 1
molecule of glucose is broken in half, producing 2 molecules of pyruvic acid
Glycolysis occurs in the cytoplasm of the cell
Glycolysis produces a total of 4 ATP, but requires 2 ATP in the beginning to get through the membrane of the mitochondria
Therefore, the NET ATP YIELD of glycolysis is 2 ATP
The Krebs Cycle
In the presence of oxygen, the pyruvic acid produced during glycolysis passes to the Krebs cycle During the Krebs cycle,
pyruvic acid is broken down into carbon dioxide in a series of energy-extracting reactions
Every time you exhale, you expel the CO2 produced by the Krebs cycle
Electron Transport Following the Krebs cycle, the electrons captured by NADH are
passed to the electron transport chain The electron transport chain uses the high-energy electrons
from the Krebs cycle to convert ADP to ATP Every time 2 high energy electrons transport down the ETC,
their energy is used to transport H+ across the inner membrane of the mitochondria…this creates a + charge on the inside of the membrane and a – charge in the matrix of the mitochondria
As a result of this charge difference, H+ ions escape through channel proteins called ATP synthase causing it to rotate
Each time it rotates, the enzyme ATP synthase grabs a low energy ADP and attaches a phosphate, forming high-energy ATP
Electron Transport Chain
Matrix
of mitochondria
inner membrane
inner membrane
space
The Energy Totals
The complete breakdown of 1 glucose molecule through cellular respiration results in the production of 36 molecules of ATP
Net Energy Gain:
38 ATP Produced
- 2 ATP needed to start
36 ATP made!
Respiration in the Absence of Oxygen
When oxygen is NOT present, glycolysis is followed by a different pathway called fermentationBecause fermentation does not
require oxygen, it is said to be anaerobic
Two Main Types of Fermentation
Lactic Acid Fermentation: glucose lactic acid (Ex: Muscles)
Alcohol Fermentation: glucose ethanol (Ex: Yeast, baking, alcohol production)
BOTH types of ANAEROBIC RESPIRATION = net gain of 2 ATP