Special Edition

October 1, 2012 - Week 7 Objectives

(Energy Harvesting)

This week you will see a change in the weekly objectives. Throughout the semester, through Surveys, I have been asking you which topics you feel comfortable about and which ones you feel are important. At the end of the week we have revisited these topics. Now after your first exam and paper, I want you to start looking at the material and looking at what you think is important.

Don't worry, you won't be alone in this. Each week, there will be a forum for you to use to discuss the Learning Goals for the week. You will still receive a weekly update, but it is up to you to start talking about what you see as important. At the end of the week, I will combine the goals that you have selected into an end of the week review, similar to the ones you've seen before. To start you off, each week, there will be some opening discussions about the weekly topic.

Energy Harvesting

Organisms have two critical needs: Carbon and Energy. Carbon is the backbone of all organic, and hence biochemical, compounds. Energy is the capacity to do work. Cells will need other compounds, such as oxygen, hydrogen, nitrogen, phosphorus and sulfar (as well as many more), but carbon is the critical atom when building biopolymers. Biologists use terms to help identify ways of acquiring carbon and energy.

Carbon Acquisition: Heterotroph vs Autotroph

Heterotrophs acquire reduced carbon compounds, generally in the form of biomolecules. If the organism can use sugars, lipids and proteins as carbon sources, then they are heterotrophs.

Autotrophs have the ability to use oxidized carbon, usually from CO₂. They have biochemical pathways that allow them to FIX carbon, that is reduce CO₂.
Energy Acquisition: Chemotrophs vs. Phototrophs

Chemotrophs harvest energy from reduced compounds. Chemolithotrophs (Bacteria and Archaea) can use reduced minerals. Chemoorganotrophs (Archaea, Bacteria and Eukarya), harvest energy from reduced organic compounds.

Phototrophs can use light energy (photons) to excit special pigments, producing reducing potential. They can convert this into chemical bonds (chemical energy). In essence, they use light to produce reduced compounds.

This week, we will focus on organisms that follow the Chemoorganoheterotrophic life style; that means we are looking at organisms that acquire energy and carbon from reduced organic compounds.

These organisms will use biochemical pathways to extract energy, and the intermediate carbon compounds (precursor metabolites) can be used as building block of other biomolecules.

Your goal this week is to understand the reactions in the biochemical pathways. You do not have to memorize the pathways, but you need a good/strong familiarity with the pathways.

Learning Goals

Looking over the chapter, the information above, and at the newsletters throughout the week, what do you see as your learning goals for this week?
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