Amylase can then hydrolyze starch if it is available in the bacterial cell's environment. Then amylase is secreted outside of the cell (amylase is an exoenzyme). The amylase gene is expressed (RNA is created from the information in the gene (the DNA) and from the RNA, ribosomes build the amylase proteins ). The information for building amylase is found in the cell's DNA. These smaller sugars can then be absorbed by the cells and the cells can use the sugars as a source of energy and carbon.įigure 2: Diagram summarizing how a bacterial cell produces and secretes amylase. The enzyme amylase is secreted out of the cells (amylase is considered an exoenzyme, meaning it is an enzyme secreted outside of the cells ) into the surrounding media, catalyzing the breakdown of starch into smaller sugars. Bacteria that can produce the exoenzyme amylase are able to hydrolyze starch by secreting these enzymes into the environment around them. Starch is too large to pass through the plasma membrane of a cell and must be split into individual glucose molecules. Amylase is an enzyme that breaks down starch into smaller sugars. Whether a bacterial species can break down starch or not is based on whether they have a gene (a segment of DNA) that codes for the enzyme amylase. Some species of bacteria can break down starch and some species of bacteria cannot break down starch. Then once inside the bacterial cell, these sugars can be used by the bacteria as a source of energy and carbon. These smaller sugars are small enough that a bacterial cell could transport them inside. The products are glucose molecules (a monosaccharide) and maltose (a disaccharide). The long polysaccharide starch is broken down (hydrolyzed) by the enzyme amylase. There is a lot of energy in starch! If bacteria are able to break down starch, this is an advantage because that means they can access the sugars in starch and the energy in those sugars (as well as the carbon).įigure 1: Above is the chemical reaction catalyzed by the enzyme amylase. Starch is a long carbohydrate molecule made of hundreds of glucose molecules bonded together into a very long chain.
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