Cellular Respiration Chapter 8.3

1. Respiration is a process in which living cells break down glucose and release its stored energy in the form of ATP

2. Respiration is necessary for life.3. Organisms obtain energy in a process

called cellular respiration.4. The equation for cellular respiration is the

opposite of the equation for photosynthesis.

Introduction

6. Cell respiration occurs in ALL cells.7. It begins with glycolysis, and continues with either

anaerobic respiration (AKA fermentation) if oxygen is absent or aerobic respiration if oxygen is present.

Introduction

First Stages of Cellular Respiration

Organic Compounds C6H12O6

Glycolysis

Aerobic RespirationFermentation

Oxygen Absent Oxygen Present

ATP

ATP

1. Occurs in the cytoplasm2. Can occur with or without oxygen3. Glucose is split into 2 molecules of pyruvic

acid (which is a 3 carbon compound)4. In addition to pyruvic acid, 2 molecules of

ATP and 2 molecules of NADH are formed for each molecule of glucose that is broken down.

Glycolysis

5. End products of glycolysisa. 2 ATP (makes 4 but uses 2 ATP)b. 2 molecules of pyruvic acidc. 2 NADHd. 2 H2O

6. What happens to the pyruvic acid depends on:a. The organism involvedb. presence or absence of oxygen

Glycolysis

Overview of Glycolysis

1. Defined as the process of breaking down pyruvic acid without the use of oxygen

2. Also called anaerobic respiration3. Does not produce ATP4. Does produce NAD+ which is reused during

glycolysis5. 2 forms of fermentation:

a. Lactic acid fermentationb. alcoholic fermentation

Fermentation

1. Pyruvic acid from glycolysis is converted into a molecule called lactic acid.

2. Heavy exercise is often the reason for the lack of oxygen that prevents pyruvic acid from continuing on to aerobic respiration. This can cause a build up of lactic acid that results in cramping and muscle soreness.

3. End products of lactic acid fermentation:a. Lactic acidb. NAD+ (used in glycolysis)c. 2 ATP (actually made during glycoysis)

Lactic Acid Fermentation

Overview of Lactic Acid Ferm.

1. Occurs in the cytoplasm of some plant cells and some unicellular organisms such as yeast under anaerobic conditions

2. Pyruvic acid from glycolysis is converted to ethyl alcohol

3. End products:a. Ethyl alcoholb. Carbon dioxidec. NAD+ (used in glycolysis)d. 2 ATP (actually made during glycolysis)

Alcoholic Fermentation

Overview of Alcoholic Ferm.

1. Occurs after glycolysis2. Occurs in the mitochondria3. Requires the presence of oxygen (aerobic)4. 3 steps to aerobic respiration

a. Formation of acetyl CoAb. Krebs cyclec. Electron Transport Chain

Aerobic Respiration

Aerobic Respiration

1. Pyruvic acid (from glycolysis) enters the mitochondria through a transport protein

2. It joins with coenzyme A (CoA) to produce Acetyl CoA

3. In the process, NADH is produced4. Acetyl CoA can then enter the Krebs cycle

Formation of Acetyl CoA

Formation of Acetyl CoA

1. AKA citric acid cycle2. Occurs in the matrix of mitochondria3. Discovered by Sir Hans Krebs in 19374. Steps:

a. acetyl enters the cycle to combine with oxaloacetic acid citric acidb. coenzyme A is released to be used againc. citric acid – carbon dioxide oxaloacetic acid (used again)

Krebs cycle

5. During the cycle, carbon dioxide is released, NADH and FADH2 are formed, and ATP is produced

6. End resultsa. 6 NADHb. 4 CO2c. 2 ATPd. 2 FADH2

Krebs cycle

Citric Acid Cycle

7. The carrier molecules (NADH and FADH2) transport electrons from the Krebs cycle to the ETC where water and more ATP are formed

Krebs cycle

1. Occurs in the inner membrane of mitochondria

2. Electrons are donated to the ETC by NADH and FADH2

3. ATP is generated by chemiosmosis4. The function of oxygen is to act as the final

hydrogen acceptor to produce water5. Each NADH produces 3 ATP6. Each FADH2 produces 2 ATP

ETC

6. The ETC produces10 NADH 30 ATP2 FADH2 4 ATP

34 ATP

ETC

Glycolysis 2 ATPKrebs cycle 2 ATPETC 34 ATP

*38 ATP from 1 molecule of glucose

Total ATP produced

Review of Aerobic Respiration

-Aerobic respiration is important because it produces way more ATP than anaerobic respiration (38 ATP to 2 ATP)

Respiration

Review of Respiration