Introduction to Photosynthesis - The Biology Project

If you want to introduce the realm of bioenergetics in a context of their possible evolutionary sequence (logically - simple to complex, and interacting with the environmental changes that are produced), you can present the Heterotroph Hypothesis, using the and provided. The diagram is best used on an overhead (or PowerPoint presentation), walking students through the phases from left to right (over time), showing the changes that each phase introduces. If one of your themes is evolution, then this introduction is an excellent way to show how these major components of the chemistry of life could have evolved. HOWEVER, PLEASE NOTE: a number of recent studies have pointed to a much different sequence of events, contrary to the long-held "heterotroph hypothesis" often found in textbooks. Be sure to read the excellent - and very readable - book Oxygen: The Molecule that made the World by Nick Lane (2002), especially Chapter 3. The author describes the many recent studies and discoveries that point to a non-intuitive sequence for the early evolution of life - mostly with multiple lines of evidene.

Course Syllabus for "BIO101A: Introduction to Molecular and Cellular Biology" ..

2. Glycolysis: If you have introduced anaerobic fermentation earlier (as part of your introduction to bio-energetics, showing fermentation as a relatively simple process by which relatively primitive cells - bacteria and yeasts - extract energy from their cells - see below), you can point to the Pre-Kreb's Cycle sequence (glycolysis) as mostly the same sequence that was found in fermentation. This follows the long-held idea* that the more efficient process of respiration must have evolved as a modification and extension of fermentation, where oxygen (accumulated from its production by photosynthesis) now serves as the ultimate hydrogen acceptor (forming water), and allows more energy to be extracted and transferred to the formation of ATP. Point out that the respiration of one glucose molecule produces 38 ATP molecules net (55% efficiency) vs 2 ATP molecules net (5% efficiency) from fermentation.


BioCoach Activity Photosynthesis Introduction

Characteristics of Life- Lesson ; What is Life PHLS- Powerpoint; Intro to Science ..