Cellular Respiration

Aerobic Processes Requires oxygen

Anaerobic Processes Do not require oxygen Ex: Fermentation

Four stages of Cell Respiration1. Glycolysis Takes place in the cytoplasm

2. Formation of acetyl CoA3. Citric Acid Cycle4. Electron Transport Chain &

chemiosmosis

Steps 2-4 takes place in the Mitochondrion

Four stages of Cellular Respiration

Summary of aerobic respiration

Glycolysis: “Sugar splitting”

◦Glucose is split into 2 molecules of Pyruvic Acid

◦Does not require oxygen◦Divided into two major phases

Energy investment phase 2 ATPs are needed to start the process

Energy capture phase 4 ATPs are produced

◦Each glucose molecule produces net yield of 2 ATPs.

Glycolysis

Formation of Acetyl CoAFormation of Acetyl CoA

◦The two Pyruvic Acid molecules generated in glycolysis are modified to 2 molecules of acetyl.

◦Then, the acetyl molecules are attached to an enzyme CoA.

◦The final product is 2 molecules of acetyl CoA.

Formationof acetyl CoA

Citric Acid CycleCitric Acid Cycle◦For every glucose, 2 acetyl molecules enter the citric acid cycle

◦6 CO2 molecules are removed & 2 ATPs are produced

◦Many electrons are generated as a result of several chemical reactions

◦Electrons are transported to the Electron Transport Chain to generate ATP.

Citric Acid Cycle

Electron Transport ChainElectron Transport Chain◦Electron carrier molecules dump the electrons down the Electron Transport Chain (ETC)

◦Electrons are then used to create bonds between ADP and Phosphate molecules to make 32 ATP molecules, through a process known as chemiosmosis

Electron transport chain

Accumulationof protons withinthe inter-membranespace

Electron transport and chemiosmosis

Energyyield fromcompleteoxidation ofglucose byaerobicrespiration

Many organisms depend on nutrients other than glucose

Products of protein and lipid catabolism enter same metabolic pathways as glucose

Energyfrom carbohydrates,proteins, and fats

FermentationFermentation◦Anaerobic process that breaks down glucose into organic compounds, 2 ATP & CO2

◦Takes place in the cytoplasm

◦Two Pathways:1. Lactic Acid Fermentation

2 ATP, Lactic Acid & 2 CO2

2. Alcoholic Fermentation 2 ATP, Alcohol & 2 CO2

Fermentation