Cellular Respiration

Topic Presenter: Edgie Tadena BSED-4 Biological Science

A Catabolic Pathway


Features: PHOTOSYNTHESIS AEROBIC RESPIRATIONRaw Materials Carbon dioxide and water Oxygen gas and glucose

End Products Glucose and oxygen gas Carbon dioxide and water

Plant cells that have these processes

Plant cells that contain chlorophyll All plant cells

Organelles involved chloroplast Cytoplasm, mitochondrion

Pathway of energy Light energy>NADPH/ATP>energy stored in carbohydrate molecule

Energy stored in fuel molecules>NADH/ATP>energy for work

in cell

Comparison of Photosynthesis and Aerobic Respiration

A series of reactions that break apart fuel molecules and transfer the energy stored in their bonds to adenosine triphosphate (ATP) for use in cellular work.

Cellular Respiration



I. Aerobic respirationII. Anaerobic respirationIII. Fermentation

Note: The type of environment a cell inhabits may determine which catabolic pathway it uses to break down fuel molecules.

3 CATABOLIC PATHWAYS

The process by which cells use oxygen to break down organic molecules, with the release of energy that can be used for biological work.


I. AEROBIC RESPIRATION


a. Glycolysisb. Formation of acetyl coenzyme Ac. Citric Acid Cycled. Electron transport and chemiosmosis


Four Stages of Aerobic Respiration


• The first stage of cellular respiration, in which glucose is split into two molecules of pyruvate with the production of a small amount of ATP.

• Pyruvate: 2 molecules of three-carbon compound called glyceraldehyde-3-phosphate (G3P)

a. Glycolysis


In cytoplasm


Acetyl coenzyme A is formed when each molecule of pyruvate produced during glycolysis passes from the cytoplasm into the mitochondrion where it is degraded to a two-carbon fuel molecule (an acetyl group) that combines with the coenzyme A (a carrier molecule).

b. Formation of acetyl coenzyme A


In Mitochondrion


A series of aerobic chemical reactions in which fuel molecules are degraded to carbon dioxide and water, with the release of metabolic energy used to produce ATP; also known as the Krebs cycle.

c. Citric acid cycle


In Mitochondrion


• The electron transport system is a chain of electron acceptor molecules embedded in the inner membrane of the mitochondrion. The electrons associated with the hydrogens releases from NADH (and FADH2) are passed along the chain of acceptors in a series of oxidation-reduction reactions.

• Chemiosmosis refers that the link between the electron transport chain and ATP synthesis is a proton gradient established across the inner mitochondrial membrane; the protons diffuse across the membrane, and their energy is used to produce ATP.

d. Electron transport and chemiosmosis


In Mitochondrion


ANAEROBIC PATHWAYS


It is the process in which energy is released from glucose and other fuel molecules without oxygen; that is, oxygen is not the final electron acceptor of electrons. Instead, an inorganic compound, such as nitrate or sulfate, serves as the final acceptor of electrons.

II. ANAEROBIC RESPIRATION


• It degrades glucose and other organic molecules without the use of oxygen.

• It depends in the process of glycolysis.• An organic molecule is the final acceptor of hydrogen in

this process.

III. FERMENTATION


i. Alcohol fermentationii. Lactate fermentation

TYPES OF FERMENTATION


• Examples: Yeasts (unicellular fungi), root cells of rice plants grown in flooded conditions

• It is the basis for the production of beer, wine and other alcoholic beverages using yeast.

• Ethyl alcohol is the end product when the pyruvate (end-product of glycolysis) splits carbon dioxide when derived with oxygen.

i. Alcohol fermentation



• Examples: certain fungi and prokaryotes• It occurs when bacteria cause milk to sour or ferment

cabbage to form sauerkraut.• In this pathway, pyruvate produced during glycolysis is

converted to lactate.

ii. Lactate fermentation


