01.02 Lipids, Carbohydrates & Proteins

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  1. Lipids (C, H, O) -Diverse Group of hydrophobic molecules
    1. Fats
      1. Store large amounts of energy
      2. Saturated Fats (animals)
        1. Solid at room temp
        2. Ex. butter, lard
      3. Unsaturated Fats (plants)
        1. Liquid at room temp
        2. Ex. oils
    2. Phospholipids
      1. Major components of cell membranes.
    3. Steroids
      1. Include cholesterol and certain hormones.
    4. Waxes
      1. Ear wax, cuticle of leaves
  2. Carbohydrates (C,H,O): Short term energy storage and building material
    1. Monosaccharides (simple Sugars, the smallest carbohydrates
      1. Ex. Glucose (blood sugar), Fructose (fruit sugar)
    2. Disaccharides (double sugars)
      1. Ex. Sucrose (table sugar), Lactose (milk sugar)
    3. Polysaccharides, the polymers of sugars
      1. Have storage and structural roles.
      2. Ex. Cellulose (cell walls), starch (plants), glycogen (animals)
  3. Proteins (C,H,O,N): main structural and functional component of a cell
    1. Polypeptide is a polymer of amino acids connected in a specific sequence.
      1. Types of amino acids – 20 total
      2. 9 essential amino acids – must be in diet
      3. 11 non-essential – the body can produce these
    2. Protein function depends on its specific shape
      1. Examples of proteins: keratin, hemoglobin, insulin (proteins tend to end -in)
    3. Enzymes
      1. Proteins that speed up the rate of chemical reactions (biological catalysts)

Nursing Points


  1. Important Metabolic Processes
    1. Gluconeogenesis
      1. Conversion of non-carbohydrate molecules into glucose.
    2. Glycolysis
      1. Splitting of sugar into pyruvic acid used for cellular respiration
    3. Protein synthesis
      1. Transcription and translation of mRNA into a polypeptide.


In this lesson we are going to discuss 3 main biomolecules that have great nutritional value to living organisms. These abundant molecules are lipids carbohydrates and proteins.

 Lipids, carbohydrates and proteins are three macromolecules important to all life and are made up of the elements carbon hydrogen oxygen and one contains even nitrogen.  An easy way to remember is the phrase CHO, CHO, CHON. Lipids and carbohydrates contain just carbon, hydrogen and oxygen and therefore are the CHO molecules and proteins also contain nitrogen and are referred to as the CHON molecules.

So we’ll start off talking about lipids. lipids are a diverse group of hydrophobic molecules and there are four main types. when you think of lipids I want you to think of long-term energy storage and the best example of that would be fats. Fats store large amounts of energy and animals in particular tend to produce what are called saturated fats. A  good example would be butter or lard. These types of fats are actually solid at room temperature. Unsaturated fats tend to come from plants and they are usually liquid at room temperature. Some examples would be canola or peanut oil. In addition to fats another type of lipid is a phospholipid which is a major component of all cell membranes. These cool molecules have hydrophobic tails (because they are made up of fatty acids) and a hydrophilic head and assemble to form a great barrier around a cell.  A third type of lipid are certain types of steroids which include cholesterol and hormones, and then lastly, waxes are another type of lipid and some examples of this would be earwax or the cuticle (shiny side) of a leaf.

The second main type of macromolecule are the carbohydrates. I want you to think short-term energy storage when you hear the word carbohydrate. Additionally carbohydrates are also used as a building material and there are three main sizes of carbohydrates. The smallest of the carbohydrates are the monosaccharides also known as simple sugars.  Examples include glucose which is blood sugar and fructose aka fruit sugar. Monosaccharides are made up of one sugar and are used in the process of cellular respiration. Next in line we have the disaccharides which are double sugars and these include sucrose which is table sugar as well as lactose or milk sugar. Last but not least there are polysaccharides which are made up of many sugars. Examples of these include cellulose which make up cell walls, starch, which is how plants store energy and glycogen which is how animals store short-term energy.

Our final macromolecule are the proteins. Proteins are made up of amino acids and there are 20 different amino acids necessary for life. 11 of those amino acids can be synthesized by the human body and are said to be non-essential, the other 9 must come from our diet and those are said to be the 9 essential amino acids. The  most basic structure of a protein is known as a polypeptide. So a protein is formed when amino acids bond together. This type of bond is called a peptide bond and polypeptides are the result of many amino acids linked together. A fun fact to tie in here is that the stomach breaks down polypeptides after swallowing a protein. So your stomach is breaking peptide bonds and then releasing amino acids into the stomach and this may sometimes require the use of Pepto Bismol or Pepcid AC as a result of breaking those peptide bonds build up more acid in the stomach. Most proteins tend to end with the letters I-N in their name. Examples of these are keratin, hemoglobin, insulin. Proteins give cells and in turn living organisms many structural components such as hair, nails, skin. In addition proteins also control many functional aspects of a cell such as the rate of chemical reactions and we refer to these proteins act as enzymes. Enzymes are proteins that act as biological catalysts and speed up rate of reactions.

So the last thing we’re going to talk about are three important metabolic processes that involved lipids, carbohydrates and proteins. The first two kind of go hand-in-hand gluconeogenesis which is a process that if the body were to be low in sugar it can tap into the building blocks of lipds and proteins and use them instead  in a new or different way to make sugar. So if you analyze that word gluconeogenesis, gluco meaning glucose, neo meaning new and genesis meaning to create this process is going to create new sugars when supplies are low or absent. Glycolysis is the process that uses glucose to make ATP/energy as part of cellular metabolism. And the third process worth pointing out is protein synthesis that uses RNA to actually create each amino acid and put them together to build proteins.No worries though this is just a brief overview of  both glycolysis and protein synthesis. We go into greater detail about both of these processes later in this video series.

In summary living organisms require three major macromolecules to be part of their nutritional requirements. Lipids are hydrophobic molecules which provide long-term energy, carbohydrates provide short-term energy and proteins give all life its structural shape as well as speed up almost every chemical reaction. Each of these play extremely important roles in metabolic processes that sustain life. 

Thank you for sharing in this human biology lesson on lipids, carbs and proteins. Now go be your best self and Happy nursing.