Cellular Respiration

•The process in which plants and animals convert glucose into “ATP” energy for the cell to use!!!

•Energy is needed for cell division, cell repair, muscle contraction, nerve impulses, creating body heat, cell transport…..to sustain your life!

Glucose + O2 CO2 + H2O+ ATP

C.R. Occurs in Plants and Animals

plants

Glucose from eating

Glucose from photosynthesis

• Aerobic: Takes place in the cytoplasm and mitochondria.

• Anaerobic takes places in the cytoplasm.

Cellular Respiration

• Process that replenishes the supply of ATP.• Bonds in glucose are broken and energy is

released (ADP is converted into ATP).• Occurs 24 hours of the day and night!!

• Note: ATP is made in photosynthesis during the light reaction. It is also made in aerobic and anaerobic respiration.

• ATP is used for transport, mechanical, and chemical work in the cell.

Cellular Respiration’s Pathway…

• CR begins with the process called glycolysis (breaking glucose).

• One glucose molecule (6 carbon compound) is converted into 2 pyruvic acid molecules (two 3 carbon compounds and 4 ATP (2 net ATP).

• Depending whether or not oxygen is present in the cell, the products of glycolysis can follow two different pathways.

Oxygen is not needed

Chemical Pathway

Glucose Glycolysis Krebs Electron

Cycletransport

chain

Fermentation alcoholic or lactic acid

With oxygen

ATPATP

Without oxygen

ATPH2O

O2CO2

Aerobic Respiration (oxygen)

• When oxygen is available, pyruvic acid enters the pathways of aerobic respiration to produce a great amount of ATP (energy for cells to use)!

• Steps include the Krebs cycle and electron transport chain.

Energy Changes Form

• Glucose – potential energy is stored in bonds from photosynthesis.

• Energy is transferred to electron carriers, FADH2 and NADH through glycolysis and Krebs cycle.

• Electrons enter the electron transport chain and a concentration gradient of H+ is formed in the mitochondria.

• Potential energy from the H+ gradient is used to make many ATP molecules in the electron transport chain.

Why all the steps?

• Why can’t the cell use energy straight from glucose?

• The energy needs to be released slowly through each step.

• Otherwise energy released too fast, creates too much heat and enzymes could be denatured.

• http://video.google.com/videoplay?docid=7433492777550198070#

Anaerobic Respiration: Lactic Acid Fermentation (no O2)

• In some bacteria cells, pyruvic acid from glycolysis is converted into lactic acid

• This process plays a role in manufacturing yogurt and cheese.

• It also occurs in muscle cells during strenuous activity when oxygen is used more rapidly than it can be delivered through the blood. (muscle fatigue)

• No additional ATP is made in this pathway.

Anaerobic Respiration: Alcoholic Fermentation (no O2)

• In yeast cells, pyruvic acid from glycolysis is converted into ethyl alcohol and CO2 is released.

• The beer and wine industry depends on alcoholic fermentation

• Bread making also depends on alcoholic fermentation

• No additional ATP is made in this pathway.

Aerobic vs. Anaerobic

• Multicellular organisms require more energy to sustain life than unicellular organisms.

• Therefore, aerobic respiration is necessary to sustain the life of multicellular organisms like animals and plants because the process creates more ATP!

• Anaerobic respiration is sufficient to sustain the life of unicellular organisms like bacteria and yeast cells because it creates a small amount of ATP.

Interdependency!

• Photosynthesis stores the energy of the sun in organic compounds while cellular respiration reverses the process by releasing the energy to be used in the form of ATP by the cell.

• The reactants of one are the products of the other and vice versa.