Meanings of Respiration 1. External Respiration – exchange of gasses (O 2 and CO 2 ) in the lungs, between the air and the blood. 2. Internal Respiration - exchange of gasses (O 2 and CO 2 ) in the capillaries, between the blood and the tissues. 3. Cellular Respiration – Production of cellular energy by the intracellular breakdown of sugars

Cellular Respiration Energy releasing process by which glucose molecules are chemically broken down to produce energy in the form of ATP ATP is used to do various types of cellular work (active transport, synthesis, maintenance, growth, repairing, and muscle work)

Glucose – C 6 H 12 O 6 – 6 atoms of carbon – 12 atoms of hydrogen – 6 atoms of oxygen O 2 – oxygen gas CO 2 – carbon dioxide gas H 2 O – water

ATP = adenosine triphosphate ADP = adenosine diphosphate P i = phosphate ADP + P i ATP energy

Aerobic – requiring O 2 Anaerobic – not requiring O 2

Cellular Respiration Simplified Formula C 6 H 12 O O ADP + 36 P i 6 CO H 2 O + 36 ATP

The Three Stages of Cellular Respiration 1.Glycolysis (does not require O 2 ). 2.The Krebs cycle (requires O 2 ). 3.Electron transport chain (ETC) (requires O 2 ).

Glycolysis One molecule glucose is partially broken down to 2 molecules of pyruvic acid (3-carbon molecules). Takes place in the cytoplasm. Primitive and inefficient process, extracting only about 5% of the energy in glucose. Occurred first in evolution, because the concentration of oxygen in the air was low.

Fermentation is glycolysis without the later steps in respiration. But in fermentation, there is a simpler second step that does not produce energy: pyruvic acid is converted to alcohol and carbon dioxide, acetic acid, or lactic acid.

Fermentation in Different Cells: Yeast cells: Glucose  CO 2 + Ethanol Cider Bacteria: Glucose  Acetic acid Sauerkraut Bacteria: Glucose  Lactic acid Anaerobic respiration in muscle cells: Glucose  Lactic acid

The Krebs Cycle and the ETC occur inside mitochondria mitochondrion

The Electron Transport Chain 1 The first carrier donates electrons to the next carrier, and so on down the line. The last electron acceptor is O 2, and H 2 O is formed. The electron movement provides energy to move hydrogen ions, pushing them into the outer compartment of the mitochondria.

The Electron Transport Chain 2 Hydrogen ions flow back into the inner compartment through an enzyme called ATP synthase. This flow causes ATP synthase to rotate, which puts P i onto ADP, thus making ATP.

The Electron Transport Chain As electrons are transported, hydrogen is pumped from the inner compartment to the outer Hydrogen flows back to inner compartment, generating ATP

ATP production from Cellular Respiration Glycolysis: 2 ATP Krebs cycle: 2 ATP ETC: 32 ATP _____________________ Total:36 ATP per molecule of glucose

External Respiration (Respiratory Systems) Large aerobic organisms need to take in oxygen and get rid of CO 2. Various respiratory systems developed in different animals, depending on their environment and their life style.

Respiratory Structures Lungs - in all vertebrates except fish Gills - in fish Skin gills - surrounded by pincers - Echinoderms/Starfish Book gills - between belly plates - some Arthropods/Horseshoe crab Tracheae and spiracles – insects (air tubes that branch internally)