HUN2201-Chapter 4 (Study Guide)

Describe the structure of a monosaccharide and name the three monosaccharides important in nutrition.

A monosaccharide is a carbohydrate with a general structure of a ring composed of carbon, hydrogen and oxygen atoms.

What happens in a condensation reaction?

Condensation combines two reactants to yield one product with the removal of water.

What is the protein-sparing action of carbohydrate?

Glucose can be used for energy, leaving protein available for its special functions.

How does the body maintain blood glucose concentrations?

Hormones are secreted in response to fluctuations in blood glucose.

What happens in a hydrolysis reaction?

Hydrolysis splits one reactant into two products with the addition of water.

What role does fiber play in the process?

In the mouth, fiber slows the process of eating and stimulates the flow of saliva. In the stomach, fiber delays gastric emptying. In the small intestine, it delays absorption of carbohydrates and fats and can bind with minerals. In the large intestine, it attracts water that softens the stools.

What are the possible fates of glucose in the body?

It can be stored as glycogen. It can be used for energy. It can be converted to fat, when carbohydrate is available.

Name the three disaccharides commonly found in foods and their component monosaccharides.

Monosaccharides important in nutrition are glucose, fructose, and galactose. Disaccharides important in nutrition are sucrose (fructose +glucose), lactose (glucose + galactose), maltose (glucose+glucose).

In what foods are these sugars found?

Nearly all plant foods contain glucose, and most plants (especially fruits and saps) contain fructose. Galactose is not found as such in foods. Sucrose occurs in many fruits and some veggies and grains. Lactose is found in milk, and maltose in seeds.

Describe the structure of polysaccharides and name the ones important in nutrition.

Polysaccharides are composed of many monosaccharides strung together. Important in nutrition are: glycogen, starch, and the fibers.

Describe carbohydrate digestion and absorption.

Salivary amylase enzymes in the mouth partially break down some of the starch before it reaches the intestine, pancreatic enzymes digest the starch to disaccharides in small intestine, disaccharide enzymes on surface of intestinal wall cells split discharges to monosaccharides, monosaccharides enter capillary, capillary delivers monosaccharides to liver, liver converts galactose and fructose to glucose.

Which carbohydrates are described as simple and which are complex?

Simple-monosaccharides: (glucose, fructose, galactose) disaccharides(sucrose, lactose, maltose) Complex- Glycogen and starch

What happens when blood glucose rises too high or falls too low?

Too high, the pancreas releases insulin, resulting in the storage of glucose in the cells. Too lose, the pancreas releases glucagon, resulting in the release of glucose into the blood.

How do the fibers differ from the other polysaccharides?

Fibers are different in that the bonds between their monosaccharides cannot be broken by human enzymes.

How are starch and glycogen similar and how do they differ?

Starch and glycogen are similar in that they are both composed of glucose. They differ in the way their glucose units are linked together. Glycogen consists of many glucose molecules linked together in highly branched chains, while starch consists of many glucose molecules linked side by side.