Cellular Respiration

Mitochondria liberate energy for work that cells do by making ATP from glucose.

Vocabulary

Cellular respiration Aerobic Glycolysis Anaerobic Krebs cycle Mitochondria Electron Transport Catabolic

ATP

Energy currency of the cell: when you work to earn money, you might say your energy is symbolically stored in the money you earn.

The energy the cell requires for immediate use is temporarily stored in ATP, which is like cash.

When you earn extra money, you may deposit some in the bank; a cell stores it in the form of lipids, starch or glycogen.

Mitochondria

Energy “powerhouse” of the cell. Bean shaped with two membranes. The inner membrane has many folds which

increase its surface area. Within these folds, little compartments are

formed called the matrix. A series of chemical reactions occur in the matrix which converts molecules (glucose) into energy (ATP).

Metabolism

Metabolism is the sum of all the chemical processes that occur in an organism.

Two types of metabolic processes:

– Catabolic: process that breaks down material to release energy.

– Anabolic: Synthetic process which builds up material to store energy.

Cell Respiration

Catabolic process: breaking down materials

Releases chemical energy from sugars and other carbon based molecules to make ATP when oxygen is present.

Aerobic process Occurs in the mitochondria; place where

most ATP is made.

Glycolysis: splitting glucose

ATP cannot be made directly from food; foods are first broken down into small glucose molecules.

In Glycolysis, glucose is split into two 3 Carbon molecules (pyruvate) and two ATP molecules are created.

Glycolysis is an anaerobic process which does not need oxygen which occurs in the cytoplasm of the cell.

Cell Respiration vs. Photosynthesis

Chloroplasts absorb energy from the sun to build sugars (photosynthesis)

Mitochondria release chemical energy to make ATP.

Formula is reversed:

C6H12O6 + 6O2 6CO2 + 6H2O

Similarities

Chloroplasts and mitochondria are similar: mitochondria are surrounded by a

membrane just like a chloroplast Two areas are involved in cell respiration-

the matrix and the inner mitochondrial membrane

Cell respiration occurs in two stages: Krebs cycle and the electron transport

Step One- Krebs Cycle (AKA Citric Acid Cycle)

1.Three carbon molecules (pyruvate) from glycolysis enter cell respiration in the mitochondrial matrix (area enclosed by the inner membrane).

– A small number of ATP molecules are made– CO2 is a waste product

Detailed animation of the Krebs Cycle: http://www.johnkyrk.com/krebs.html

Step Two- Electron Transport Chain

2. ATP molecules from glycolysis and Krebs cycle enter the chain of proteins located in the walls of the inner membrane of the mitochondria.

– A large number of ATP molecules are made in the presence of oxygen.

– Waste products are H2O and heat

More detailed animation at:

VCAC: Cellular Processes: Electron Transport Chain: The Movie

End products of entire process

Up to 38 ATP molecules are made from the breakdown of one glucose molecule.

- 2 from glycolysis

- 34 to 36 from cell respiration Many enzymes are part of the process. FYI: Cell Respiration equation includes

glycolysis.

Review

1. How are cellular respiration and glycolysis related?

2. Summarize the aerobic stages of cell respiration (Include the Krebs Cycle and Electron Transport Chain)

3. What is the relationship between photosynthesis and cell respiration?

4. Is cell respiration an endothermic or exothermic reaction?