1. Module 5 Intro

1.5. Page 3

Lesson 1

Module 5—Photosynthesis and Cellular Respiration

Read

 

Metabolic Pathways

 

This drawing depicts the hundreds of metabolic pathways. It looks like a map of a subway system. Like train stations, there are straight lines and curves and dots at intersecting points. Each type of metabolism is indicated by a colour. For example, energy metabolism is indicated by purple. The purple lines radiating from this area are at some point connected to all the other metabolic pathways shown.

© Dept. of Computer Science, University of Helsinki. Used with permission.

 

metabolism: all of the chemical reactions that occur within a cell to support and sustain its life functions

 
This can be the synthesis of molecules or the breaking down of molecules for energy.

Metabolic pathways are interconnected and involve many steps. Plants and animals rely on metabolic pathways to store and provide energy. These pathways can be summarized by the word metabolism.

 

Photosynthesis and cellular respiration are two important pathways. They can be represented by the following two formulas:

 

6 CO2(g) + 6 H20(l) + energy → C6H12O6(s) + O2(g)

 

C6H12O6(s) + O2(g) → 6 CO2(g) + 6 H20(l) + energy

 

The important thing to keep in mind is that these are summary statements. Both processes are a series of reactions that use initial reactants to produce final products.

 

The series of reactions becomes a metabolic pathway. Metabolic pathways transfer energy and cycle matter. The products of one reaction become the reactants for the next reaction. You will be learning about the series of reactions in the following lessons.

 

Self-Check

 

SC 6.  True or False: Cellular respiration is the same as breathing.

 

Check your work.
Self-Check Answer

 

SC 6.  False. Cellular respiration is how the cell derives useable energy from glucose. Breathing, which is fuelled by the energy of cellular respiration, refers to the gas exchange of CO2 and O2. These elements are necessary products and reactants for cellular respiration.