Lecture 5 (Part 2)

Question 1

what enzyme hydrolize/break down carbohydrates

Answer 1

Glycosidases/carbohydrases hydrolize/break down carbohydrates

Question 2

where does most digestion of polysaccharides takes place

Answer 2

small intestine

Question 3

In the duodenum, why is PH elevated by bicarbonate to a level that is compatible with the activation of the enzyme;

Answer 3

Raise in pH allows the activity of the enzyme to increase in order to perform its job (to chop molecule down)

Raise in Ph in duodenum → increase enzyme activity → better perform job in chopping down molecules

In-Depth explanation:
optimises pancreatic alpha-amylase activity which
allows polysaccharides in the chyme to be digested in a stepwise fashion (chopping up the big molecules into small ones that are easier to absorb)

Question 4

Digestion Steps for amylopectin and glycogen

Answer 4

1a. The digestion of amylopectin begins with Alpha-amylase (salivary and pancreatic) acting on amylopectin

1b. However, alpha-amylase cannot hydrolyse alpha(1-4) that are close to alpha(1-6), or alpha(1-6) by itself (does not break these bonds)

2a. Alpha amylase starts breaking down amylopectin into shorter polysaccharides.

2b.Oligosaccharides, maltose (disaccharide), and maltotriose (trisaccharide), are derived from this process

3a. The brush border enzymes, located on the surface of the small intestine lining, include glucoamylase (AKA Alpha-limit dextrinase).

3b.Glucoamylase removes a single glucose unit from the ends of linear a(1-4) glucosyl chains of dextrins and produces isomaltose

3c. Isomaltose: a disaccharide with one unit attached
by an a(1-6) glycosidic bond)

4. Alpha(1-6) glucosidase, located in the brush border, Hydrolyzes a(1-6) bonds

5.Alpha(1-6) glucosidase (AKA isomaltase), Located in the brush border, is the enzyme responsible for the hydrolysis of a(1-6) bonds

6a. Disaccharidases are enzymes that catalyze the hydrolysis/breakdown of disaccharides, breaking them down into their constituent monosaccharides which can be transported and absorbed

6b. Disaccharidases like lactase, sucrase, isomaltase, and trehalase, are located within the microvilli of the small intestine. Hydrolyzes disaccharides

6c.Enterocytes produce and release disaccharidases into the brush border