Forms of Carbohydrates, Lipids, and Proteins


Starch, sugars, and dietary fibers are the forms of carbohydrates. Starch consists of multiple monosaccharaides bonded in a polysaccharide strand. Bread, whole grains, cereals, and rice are some food sources of starch (Eliasson, 2016). Sugars digest fast and are quickly absorbed into the bloodstream. Sources of simple sugars are milk, fruits, sports drinks, and yogurt. Dietary fibers are not absorbed but excreted from the body since the digestive system lacks the necessary enzymes to break them down. They are found in vegetables, fruits, and whole grains.


The three forms of lipids are sterols, phospholipids, and triglycerides. Cholesterol, the best-known sterol, is an essential element of the cell membrane required to synthesize sex hormones, bile salts, and vitamin D (Rauter et al., 2020). Phospholipids are water-soluble and are found in both animals and plants. They are synthesized in the body to form organelle and cell membrane. Triglycerides exist in vegetable oil, whole milk, fried foods, butter, and some meat. As with most fats, triglycerides do not dissolve in water.


Proteins’ forms are fibrous, globular, and membrane, consisting of a variety of functions. Fibrous proteins include Actin, Keratin, and Spectrin, and they form muscle fiber, connective tissue, tendons, and bone. While globular proteins have Albumins, Fibrin and Hemoglobin are the most soluble proteins. Their roles are regulating catalyzing and transporting. Lastly, membrane proteins relay signals within cells, transport molecules, and allow cells to interact. Hydrolases and glucose transporter are some membrane proteins.

Identifying Macromolecules using Biochemical Tests

Benedict’s reagent tests the reducing sugars while the iodine test determines the presence of starch for carbohydrates. The Biuret test detects proteins while lipids are seen by their ability to absorb pigments in the fat- soluble dye.

The abundance or deficiency of macromolecules in the body is dangerous. For instance, the absence of lipids makes physical movement slow due to a lack of energy. Its abundance, too, causes diseases in the body. Similarly, the body’s lack of proteins results in death since all cells need them to function—high protein intake results in increased risks of coronary heart disease (Ur Rehman et al., 2017). Low carbohydrate intakes drop the sugar levels, causing ketosis, while its abundance causes chronic fatigue and other health issues.


Eliasson, A. (Ed.). (2016). Carbohydrates in food (3rd ed.). CRC Press.

Rauter, A. P., Christensen, B., Somsak, L., Adamo, R., & Kosma, P. (2020). Recent trends in carbohydrate chemistry: Synthesis and biomedical applications of glycans and Glycoconjugates (1st ed.). Elsevier.

Ur Rehman, H., Azam, N., Yao, J., & Benso, A. (2017). A three-way approach for protein function classification. PLOS ONE, 12(2), 3-17. Web.