112L-Lab#8, Enzyme Function

Yes, but it will be less efficient because lipase cannot access lipid in the center of a drop. Bile increases the surface area for lipase action by increasing the number of small lipid droplets - this increases the surface area exposed to lipase.

Can lipid digestion occur without bile?

High temperatures or temperatures above optimal will increase reaction rates. If the temperature is too high, the enzyme will denature and will not function.

How will high temperatures affect the ability of enzymes to function?

Lower temperatures or temperatures below optimal will slow reaction rates.

How will low temperatures affect the ability of enzymes to function?

The pancreas; pancreatic lipase

In the small intestine, what is the source of lipase that acts on lipid in micelles?

Alkaline, basic

Is a high pH acidic or basic?

Acidic

Is a low pH acidic or basic?

Low, it is acidic.

Is a pH of 2 a high pH or a low pH?

Lactose, maltose, sucrose

What are the main disaccharides that can result from the action of amylase?

Monoglycerides and fatty acids.

What are the main products of pancreatic lipase acting on lipids in the intestine?

Pepsin is the gastric protease and it releases poly peptides (long chains of amino acids) from proteins in the stomach.

What are the main products of the gastric protease acting on proteins in the stomach?

The brush border is the microvilli of the small intestine. Cells here secrete enzymes for carbohydrate digestion (amylase, lactase, maltase, sucrase, dextrinase) and enzymes for protein digestion (aminopeptidase, carboxypeptidase, dipeptidase)

What digestive enzymes are secreted by brush border cells?

Carboxypeptidase along with trypsin and chymotrypsin are pancreatic enzymes that cut large polypeptides into smaller polypeptides. Carboxypeptidase can also release single amino acids from peptides.

What does carboxypeptidase do?

Pepsin is a protein digesting enzyme secreted by cells in the stomach (secreted as pepsinogen, HCl converts pepsinogen to pepsin in the lumen of the stomach). After HCl has denatured a protein (taking it from a tertiary to a primary structure) pepsin cuts the chain of amino acids into long polypeptides.

What does pepsin do?

Sucrase from brush border of small intestine.

What enzyme digests the disaccharide called sucrose, and what cells produce this enzyme?

Amylases release disaccharides. This occurs in the mouth (salivary amylase) and in the small intestine (pancreatic amylase)

What enzyme releases disaccharides, and what substrate does it work on?

Brush border of small intestine produces aminopeptidase, carboxypeptidase, and dipeptidase which release amino acids from peptides (peptides are released by proteases acting on proteins).

What enzymes release amino acids from peptides, and where in the digestive tract does this occur?

Saliva is released form the parotid, submandibular and sublingual salivary glands. Saliva includes water and enzymes. Salivary amylase comprises most of the enzyme released in saliva.

What glands, cells or organs are responsible for the production and secretion of salivary amylase.

Pepsin functions in the stomach, low pH, so when it enters the small intestine as part of chyme moving out of the stomach, the action of pepsin will stop. The pH of the intestine is too high for pepsin.

What happens to the ability of pepsin to function when it enters the small intestine?

Salivary amylase is secreted into the mouth, near neutral pH. It denatures and stops functioning when it encounters the low pH of the stomach.

What happens to the ability of salivary amylase to function when it enters the stomach?

A droplet of lipid surrounded by bile.

What is a micelle?

Amylases

What is the general class of enzyme is responsible for the breakdown of carbohydrates into disaccharides?

Lipase, most of which comes from the pancreas.

What is the general class of enzyme responsible for the breakdown of lipids into monoglycerides and fatty acids?

Protease. Pepsin is the gastric protease (in the stomach); trypsin, chymotrypsin, and carboxypeptidase are pancreatic proteases secreted into the small intestine.

What is the general class of enzyme responsible for the breakdown of proteins?

Lipids, bile is an emulsifier which causes large droplets of lipid to form smaller droplets.

What is the main class of nutrient that bile acts on?

Neutral, around 7

What is the optimal pH for digestive enzymes secreted in the mouth?

Neutral to alkaline (high pH)

What is the optimal pH for digestive enzymes secreted in the small intestine?

Acidic, a low pH, around 2

What is the optimal pH for digestive enzymes secreted in the stomach?

Pepsin

What is the protein digesting enzyme secreted into the stomach?

Bile produced in the liver is stored in the gall bladder. From there, bile is released into the small intestine.

What is the role of the gallbladder in bile secretion?

Carbohydrates

Which class of nutrient does amylase digest?

Bile - Pancreatic lipase - Lingual lipase - Gastric lipase

Which of these are enzymes or molecules which are involved in the digestion of lipids?

Salivary amylase - Lactase - Maltase - Sucrase - Pancreatic amylase

Which of these are enzymes that digest carbohydrates?

Pancreatic lipase - Lingual lipase - Gastric lipase

Which of these are enzymes that digest lipids?

Dipeptidase - Chymotrypsin - Pepsin - Carboxypeptidase - Trypsin - Aminopeptidase

Which of these are enzymes that digest proteins?

Bile

Which of these enzymes / molecules are produced in the liver and released into the small intestine?

Chymotrypsin - Carboxypeptidase - Trypsin - Pancreatic amylase - Pancreatic lipase

Which of these enzymes / molecules are produced in the pancreas?

Carboxypeptidase - Aminopeptidase -Lactase - Dipeptidase - Maltase - Sucrase

Which of these enzymes / molecules are produced in the small intestine?

Salivary amylase - Lingual lipase

Which of these enzymes / molecules are secreted in the mouth?

Pepsin -Gastric lipase

Which of these enzymes / molecules are secreted in the stomach?

Pancreatic amylase - Lactase - Maltase- Sucrase - Dipeptidase - Chymotrypsin -Carboxypeptidase - Trypsin - Aminopeptidase - Pancreatic lipase - Bile

Which of these enzymes / molecules function in the small intestine?

Pepsin - Gastric lipase

Which of these enzymes/molecules function in the stomach?