Cellular Metabolism: An Overview SBI4U Biology

Recall Some Metabolism Facts: Metabolism = the use of energy Catabolic & Anabolic Processes Enzyme mediated Mitochondrion C6H12O6 + O2  H2O + CO2 + ATP

Cascades & Cycles Metabolic Reactions are linked “chain reactions”… sort of. Straight line = Cascade Circular = Cycle

Cascades Think waterfalls and fountains The product of one reaction becomes the reactant of the next.

Cascades An example of an enzyme-mediated cascade.

Cycles Think carousels & wheels. The product of each reaction becomes the reactant of the next, but the final reaction generates the first reactant again.

Cycles An example of an enzyme-mediated cycle.

The Mitochondrion Four Metabolic Regions: Outer Membrane: for fatty acid metab. Inner Membrane (Cristae): enzyme-rich Intermembrane space: tiny but vital! Matrix: central fluid, also enzyme-rich

Each Eukaryotic Cell has many Mitochondria. The Mitochondrion Each Eukaryotic Cell has many Mitochondria.

The Four Metabolic Regions

The Mitochondrion Many Cristae = increased surface area More places for reactions to occur More enzymes to catalyze them

Extracting Energy A General Overview: Initial Processing of Glucose in the Cell’s Cytoplasm. Products move to Mitochondrion, for reactions in the Matrix. Those products are processed by enzymes on the Cristae & in the Intermembrane space.

The path of Glucose & its products Extracting Energy The path of Glucose & its products

Stage 1: Glycolysis Glyco = Sugar Lysis = breaking 10 reactions that break down 6C Glucose into two molecules of 3C Pyruvate. Cascade In Cytoplasm.

Stage 2: Krebs’ Cycle Citric Acid Cycle Continues with Pyruvate, which must enter the Mitochondrion Ten Reactions Cycle In Matrix

Stage 3: Oxidative Dephosphorylation Final stage Chain of redox reactions Cascade On cristae & in intermembrane space.

Here’s how it all fits in:

Why do all of this? Gradual release of glucose’s energy Formation of ATP – Adenosine Triphosphate ATP = The energy ‘currency’ of all life.