Digestion and Absorption of Carbohydrates

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Questions and Answers

What are the chief carbohydrates found in our food, and what are they hydrolyzed into before intestinal absorption?

The chief carbohydrates in our food are starch, glycogen, sucrose, lactose, and cellulose. Before intestinal absorption, they are hydrolyzed into monosaccharides, including glucose, galactose, and fructose.

Explain the role of salivary α-amylase in the digestion of carbohydrates in the mouth.

Salivary α-amylase, also known as ptyalin, is an enzyme produced by the salivary glands. Its optimal pH is 6.7, and it is activated by chloride ions (CI-). It acts on cooked starch and glycogen, breaking α 1-4 bonds and converting them into maltose, a disaccharide containing two glucose molecules attached by α 1-4 linkage.

Briefly explain the process of carbohydrate digestion by salivary α-amylase in the mouth.

Salivary α-amylase acts on cooked starch and glycogen, breaking α 1-4 bonds and converting them into maltose, a disaccharide containing two glucose molecules attached by α 1-4 linkage. It is activated by chloride ions (CI-) and has an optimal pH of 6.7.

What are the key components of the digestible carbohydrates and the enzymes responsible for their hydrolysis?

<p>The key components of digestible carbohydrates are starch and glycogen, which are hydrolyzed into monosaccharides (glucose, galactose, and fructose) before intestinal absorption. A family of glycosidases catalyzes the hydrolysis of glycosidic bonds.</p> Signup and view all the answers

What is the significance of the presence of α 1-6 bonds in both starch and glycogen during their digestion?

<p>The presence of α 1-6 bonds in both starch and glycogen results in the formation of isomaltose during their digestion. Isomaltose is a disaccharide in which two glucose molecules are attached by α 1-6 linkage.</p> Signup and view all the answers

Flashcards

Salivary α-amylase role

Salivary α-amylase breaks down cooked starch and glycogen into maltose in the mouth.

Carbohydrate digestion in mouth

Salivary α-amylase starts breaking down complex carbs in the mouth into smaller units (like maltose).

Digestible carbs

Starch and glycogen are the main digestible carbohydrates.

α1-6 bonds in starch/glycogen

Presence of these bonds leads to isomaltose formation during digestion.

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Hydrolysis of digestible carbs (end product)

Digestible carbs are broken down into monosaccharides (glucose, galactose, fructose).

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Study Notes

Chief Carbohydrates in Food

Major carbohydrates include starch, glycogen, and dietary fiber.
These carbohydrates are hydrolyzed into simple sugars like glucose, fructose, and galactose before absorption in the intestine.

Role of Salivary α-Amylase

Salivary α-amylase initiates carbohydrate digestion in the mouth.
It breaks down starch and glycogen into smaller polysaccharides and oligosaccharides.

Process of Carbohydrate Digestion by Salivary α-Amylase

Carbohydrate digestion starts in the mouth when food is mixed with saliva.
Salivary α-amylase cleaves α-1,4 glycosidic bonds in starch and glycosyl links in glycogen.
This enzymatic action produces maltose, maltotriose, and dextrins, which later undergo further digestion in the small intestine.

Key Components of Digestible Carbohydrates

Digestible carbohydrates primarily consist of starch and glycogen.
Enzymes responsible for hydrolysis include salivary α-amylase, pancreatic α-amylase, maltase, isomaltase, and lactase.

Significance of α-1,6 Bonds in Starch and Glycogen

α-1,6 bonds are crucial for branching in starch and glycogen structures.
They create multiple endpoints for enzymatic attack, enhancing the efficiency of carbohydrate digestion and glucose release.