01.07 Intro to Cell Metabolism

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Included In This Lesson



  1. Cell Metabolism- the sum of all biochemical reactions in the cells
    1. Two main types of biochemical reactions
      1. Anabolism- the combining of monomer molecules to create polymers (overall storage of energy)
        1. examples include protein synthesis, glycogen storage, photosynthesis
      2. Catabolic- the breakdown of larger/polymers into smaller molecules (overall release of energy)
        1. examples include glycolysis, beta oxidation, krebs cycle, oxidative phosphorylation
    2. Every metabolic reaction in a cell is either anabolic or catabolic and they tend to be coupled.
    3. Two main ways cells convert energy
      1. Aerobic Cellular Respiration (in the presence of oxygen)
        1. most efficient (1 glucose yields up to 38 ATP)
      2. Anaerobic Cellular Respiration (in the absence of oxygen)
        1. Inefficient (1glucose yields 2 netATP)


Hello and welcome to this lesson where we take a peek into the metabolism of our cells.

So the image above is not intended to be readable, but to demonstrate the numerous metabolic pathways that exist within our bodies. (and this isn’t even depicting it all). Your metabolism is by definition the totality of all of these reactions.

This metabolic chemistry is quite overwhelming to say the least, but honestly we can kinda boil down all of these metabolic reactions into two categories; either being anabolic or catabolic. Any reaction that creates more order…. in other words combines smaller molecules into larger one is said to be anabolic. A good way to remember this is to think of anabolic steroids and how they are associated with building muscle. Anabolic reactions are storing energy during this process, and will not happen spontaneously (in other words it’s going to require the input of energy to make this happen).  Some great examples of this are protein synthesis, glycogen storage and photosynthesis. 


The other category of metabolic reactions are those considered catabolic. These reactions break down larger molecules into smaller ones and in the process tend to release energy. This process tends to be spontaneous and tend to create more disorder. A good way to remember this is to think Katabolic= Kaboom! The many parts of cellular respiration are all great examples of catabolism.

So all reactions are either catabolic or anabolic and they really go hand in hand. One releases energy, the other then uses that energy to create something larger and in turn stores up energy. An example of coupling can be seen in this graphic where food molecules are being broken down and then the energy released in that process is used to build cell components.

Cellular respiration will be discussed in greater detail in the next lesson but it’s worth mentioning now the two main ways this process can continue. Aerobic and anaerobically. Cellular respiration with oxygen is said to aerobic and that’s the most efficient manner in which our cell can produce ATP. You might recall that the whole purpose of CR is to take glucose and convert it  into ATP (the common energy currency for all cells).In the presence of oxygen cells can convert one molecule of glucose into approx 36 ATP. Without oxygen (anaerobic CR) cells are much less efficient only 2 net ATPs from one glucose. Yeast and bacteria cells maintain anaerobic CR through alcoholic fermentation and animal cells fuel glycolysis through lactic acid fermentation. Bottom line, oxygen is necessary to keep our cells making ATP to keep us alive. Which by the way is the whle reason we need to breathe.

So in summary, your metabolism is the sum of all the chemistry in your cells. There are two main types of chemistry happening in your cells, catabolic and anabolic. Catabolic breaks down (kaboom) and anabolic builds up (like anabolic steroids/muscles).  All cells respire and this can take place most efficiently and sustainably for animals in in the presence of oxygen (aerobically). 

Thank you for allowing me to introduce cell metabolism with you, now go out and be your best self today and happy nursing!