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