Photosynthesis: Overview

Learning Objectives 

By the end of next week, you should be able to:

• • Compare and contrast consumers and producers; their source of organic molecules, their use of cellular respiration vs. photosynthesis
  • Understand that organic molecules can be used for generating ATP vs. growth or repair
    • the role of cell respiration and photosynthesis
    • the ability to construct any type of subunit from sugar ( with added N--> amino acids; with added N=P--> nucleotides , with enough sugar--> fatty acids) and therefore macromolecules. 
  • Explain what happens to different wavelengths of light with different pigments
  • the relationship between different wavelengths and their color and energy 
  • what determines the color of a pigment: absorbed vs reflected/transmitted wavelengths 

Content 

Organic Molecules: Cell respiration vs.  Growth and Repair

All living organisms use organic molecules  and the process of cellular respiration to generate the ATP they need for their energy needs.  But organisms don't j

ust need energy. They also need to repair cell structures, grow and reproduce.  So the organic molecules that  you consume, has to be enough for both your energy needs (cellular respiration) AND your need to repair cell structures that get damaged through day to day living. 

This means that there are two options for every organic molecule you eat you can do EITHER 

• • • • Cellular respiration - generates ATP, but destroys the organic molecule in the process
      • Growth/Repair- build new molecules with the organic molecules you eat. (Note: reproduction is a variation on this idea) 
      • But you can't use the same molecule for both!

Consumers and Producers

All organisms on earth can be broken up into two main categories: consumers and producers.   

• • • • • Consumers need to eat organic molecules that they then use for cellular respiration or growth/repair.  
        • Producers are organisms that can make their own organic molecules. They can then use those organic molecules for cellular respiration or growth/repair. 

Since consumers depend on producers, every ecosystem on earth has a mixture of both these types of organisms, but always MORE producers than consumers or else the system would collapse. 

Producers and Photosynthesis 

Producers make their own organic molecules through a process called photosynthesis. For this process to work, producers need the following

• • • • CO2, H2O = the raw ingredients needed to make organic molecules
      • Light = the energy for making the organic molecules ( building the chemical bonds)
      • Photosynthetic pigments= the machinery to capture light energy
      • Proteins and Enzymes for the two stages of photosynthesis- the machinery to make organic molecules. 

Light Energy and Photosynthetic Pigments 

Light energy is moves in waves and different colors of light have different wavelengths. 

Pigments are molecules that absorb specific wavelengths of light. Photosynthetic pigments are ones that are hooked up to the photosynthetic proteins in a chloroplast. 

Video 

Watch this video and answer the questions embedded. Some of the questions will come from the content above, so you will need to refer to that  information.