Chemical Reactions and Equations

What is Substrate – Definition and Examples

Introduction to Substrate

A substance to which another substance is applied we call it as a substrate. Its definition is different in different sciences. According to biology, it is a medium on which flora, fauna or fungi lives.

In chemistry, it is a molecule or a compound that undergoes a chemical reaction, whether under the action of a catalyst, an enzyme or an inhibitor. According to geology, it is the underlying layer of rock or other materials found beneath the soil. For example, rock is a substrate for fungi, a page is a substrate on which ink adheres, NaCl is a substrate for the chemical reaction.


Substrate Biochemistry

In biochemistry, it is a substance on which an enzyme acts. This substance is added into the active site of the enzyme. In other words, we can say that an active site is a place that allows the formation of weak bonds between the two molecules.

This result in the formation of an enzyme-substrate complex and the enzyme exerts a force on this substance due to which it reacts and become the product of the initiated reaction. The conformational change or change in the shape of the enzyme occurs due to the bonds that form between this substance and enzyme. The change in the shape of the enzyme applies pressure to this substance, either by forcing molecules to come together or making them apart from each other.

Substrate in Chemistry

In chemistry, it is the medium in which chemical reaction takes place. In other words, this substance is typically the reactant of the chemical reaction.

It is the chemical component acted upon the substance and changed it into a new product by the reaction. At the end of the reaction, the original substrate reactant will no longer have the same chemical composition.

Substrate in Biology

In biology, the surface on which an organism such as a plant, fungus, or animal lives we call it as a substrate. This surface can include all biotic, abiotic components as well as animals. For example, algae that live on a rock, here rock acts as this surface and algae act itself as this surface for an animal that lives on top of the algae.

The surface on which a cell or an organism grows such as the use of microcarriers in cell culture is a substrate for that cell or organism. Most of the eukaryotic cell requires attachment to this surface for their survival.

They have extracellular matrices in their body. These are mainly composed of proteins and provide chemical cues that affect or guide the behaviour of cells.


  • Carbohydrates like glucose, sucrose, starch act substrates for enzymes like salivary amylase, maltase.
  • Amino acids, peptides, proteins act as substrates for enzymes trypsin, chymotrypsin, etc. These proteins are present in grams, the meat we eat.
  • Fatty acids act as a substrate for lipase enzyme by the synthesis in the body.
  • Nucleic acids DNA and RNA are substrates for nuclease enzyme.
  • Ethyl alcohol breaks down by the enzyme alcohol dehydrogenase.
  • Lactose is a sugar whose production takes place in milk. Mammals typically produce milk for their offspring. It contains a blend of fats, proteins, and growth hormones to get a young mammal to gain a lot of weight in a short amount of time.

Solved Question for You

Q: A particular molecule binds to the active site of an enzyme, which results in the formation of an enzyme-substrate complex, but no change happens in the molecule and it stays bound to the enzyme. Which type of molecule is this?

  1. Substrate
  2. Inhibitor
  3. Intermediate

Ans: B is correct. Inhibitor acts in the same way as a substrate molecule acts binding to the active site.

The inhibitor is not able to undergo a reaction. So, the enzyme stays bound to it until other forces allow the two molecules to separate.

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