Cellular Metabolism An Overview SBI 4 U Biology

Cellular Metabolism: An Overview SBI 4 U Biology

Recall Some Metabolism Facts: • • Metabolism = the use of energy Catabolic & Anabolic Processes Enzyme mediated Mitochondrion • C 6 H 12 O 6 + O 2 H 2 O + CO 2 + 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

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.

Extracting Energy • The path of Glucose & its products

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