3. Hydrolysis of disaccharides Flashcards
Hydrolysis is the opposite reaction to condensation.
Condensation is a reaction that occurs between two hydroxy groups of two monosaccharides. The reaction results in a glycosidic link forming between the two monosaccharides, and a water molecule is eliminated.
Hydrolysis is the breakdown of a compound due to what?
A reaction with water.
For carbohydrates, hydrolysis is the reaction that breaks the ___ by adding the water molecule back in.
Glycosidic link.
In the human body, hydrolysis is catalysed by what?
Enzymes.
Enzymes are substrate specific which means that one enzyme can only catalyse one reaction. Therefore, sucrose, maltose and lactose all require different enzymes to hydrolyse them into monosaccharides. Fortunately, the enzyme names are pretty easy to remember. They are:
Hydrolysis of disaccharides occurs in the ileum. The ileum is the last part of what?
The small intestine.
The ileum is the last part of the small intestine. This is where the enzymes maltase, lactase and sucrase are found. Once they are broken down into monosaccharides, the carbohydrates are small enough to be absorbed from the digestive tract into the blood. From there, the monosaccharides are used as energy for the cells in the body or stored _______ as glycogen to be used later.
In the liver.
What happens with hydrolysis reactions of disaccharides?
People who are lactose intolerant do not have enough what?
Lactase.
When someone who is lactose intolerant consumes lactose, the lactose disaccharides pass through the intestine without being hydrolysed and absorbed. The undigested lactose then reaches the large intestine, where anaerobic bacteria can break down the lactose into what?
Hydrogen, carbon dioxide and methane.
Is lactose intolerance an allergy?
It’s important to note that lactose intolerance is not an allergy. Some people are allergic to certain proteins in cow’s milk, but an allergy is a reaction that involves a response from your immune system. Food intolerances, like lactose intolerance, are caused by an inability to properly digest the food.
Polysaccharides are much bigger than disaccharides, therefore their digestion involves a few extra steps.
The enzymes found in the small intestine can only hydrolyse _____
Disaccharides into monosaccharides.
The first stage of starch hydrolysis begins where?
In the mouth.
Salivary amylase is an enzyme found in our saliva. This enzyme is able to begin hydrolysing the glycosidic bonds between the glucose molecules in starch. However, this enzyme only hydrolyses every second glycosidic link. Therefore, the starch is broken down into what?
Maltose.
Food is not in your mouth for very long, so most of the starch will remain unhydrolysed at this point. When you swallow your food, the salivary amylase will continue hydrolysing for a while, but eventually, the acidity in your stomach will denature the enzyme.
Fortunately, another form of amylase, called pancreatic amylase and produced by the pancreas, can continue the work of the salivary amylase in which organ?
Small intestine.
The pancreatic amylase will hydrolyse any remaining starch polymers in the stomach into _______, to be hydrolyzed by maltase in the small intestine.
Maltose disaccharides.
Glycogen is a highly branched molecule, even more branched than amylopectin. This means there are lots of different points where hydrolysis can take place, and hydrolysis can take place ______.
Quickly. Therefore, the body can ensure glucose is available as soon as it needs it.
