Chapter 14 Digestion: CHEM 351 Exam 2

a-amalyse

An enzyme that hydrolyzes α-1,4 linkages of starch and glycogen but not α-1,6 linkages. It is found in saliva (products are the disaccharides maltose and maltotriose). The pancreas also secretes it into the small intestine. Its catalytic activity generates limit dextrin, maltotriose, and maltose.

Bile salt

an amphipathic derivative of choloestrol, this is made in the liver, and stored in the gallbladder. In response to CCK it is released into the small intestine, where they insert into lipid droplets, this further emulifies the lipid droplets, which allows lipase to catalyze the hydrolysis of ester linkages from tryglycerides into absorable fatty acids.

Cholecystoknin (CCK)

A peptide hormone secreted by cells in upper small intestine, the stimulated the release of bile salte by the gall bladder, and digestive enzymes by the pancrease.

Chylomicron

An assembly of lipids and protien, a lipoprotien that transport dietyry triacyglycerides from the intesting to other tissues. This lipoprotien is assembled in the smooth endoplasmic recticulum of intestinal cells (In SER, fatty acids and monoglycerols are resymthisized into triglycerols)

Digestion

Breaking down large molecules into smaller units using hydrolytic enzymes (protiens → amino acids) (polysaccharides → glucose/ simple sugars) (fats → glycerol and fatty acids)

Emulsion

mixture of lipid droplets in water

Enteropeptidase

A protelytic enzymes ancored to eputhelial cells in the small intestine, it activates trypisogen (trypsiogen is released by the pancrease and “brushes up” with enteropeptidase)

Lipase

An enzymes secreted by the pancrease into the small instestie that attatches to the surface of a lipid and degrades triacyglycerol into a free fatty acid and monoglycerol

micelle

globular structure formed by amphipathic molecule in aqueous solution. Formed my small lipids. When free fatty acids/monoglycerols assemble into micelles after being hydrolyzed by lipase, this is how they are carried into intestional cell. Bile salts help in their formation.

pepsin

a protelytic enzyme that begins the process of protien and nucleaic acid degrdation in the stomach. Yields protien fragments that will later be degraded further by proteases in the intestine (proteases like enteropeptidase, trypsin, and chymotrypsin). Spectacular enzyme cause it can function at the low pH of the stomach.

protease

An enzyme that catalyzes the hydrolysis of peptide bonds. Also called a proteolytic enzyme (examples: pepsin and proteases like enteropeptidase, trypsin, and chymotrypsin)

Secretin

a hormon released by samll intesting in response to low pH of stuff coming from the stomach, this hormone tells the pancrease to release sodium bicarbonate which neutrlizes the pH of the acidic slurry coming from stomach

Trypsin

A pancreatic enzyme that digests dietary proteins and activates most of the pancreatic zymogens. It is activated by enteropeptidase.

Zymogens/Proenzymes

Catalytically inactive precursors of an enzyme released by the pancrease into the small intestine. They are activated by protelytic cleaveage, cleaved by another protelytic enzymes, typically another protease.

Mastication (Chewing)

Increases the overall surface area of the food, making it more accessible to hydrolytic enzymes, makes the food more homogenized.