hun ch 4

______These carbohydrates—and all the other energy nutrients—are put together and taken apart by similar chemical reactions: condensation and hydrolysis.

disaccharides

fructose is absorbed by

facilitated diffusion

The monosaccharide _____ occurs naturally in foods as a single sugar only in very small amounts.

galactose

The conversion of protein to glucose is called

gluconeogenesis

Commonly known as blood sugar, ----- serves as an essential energy source for all the body's activities. glucose is one of the two sugars in every disaccharide and the unit from which the polysaccharides are made almost exclusively

glucose

Sucrose

glucose + fructose

Lactose

glucose + galactose

maltose

glucose + glucose

two carbohydrates——provide about half of all the energy muscles and other body tissues use. The other half comes mostly from fat.

glucose and its storage form glycogen

the storage form of glucose is

glycogen

Three types of polysaccharides are important in nutrition:

glycogen, starches, and fibers.

To break a disaccharide in two, a chemical reaction known as ______ occurs. A molecule of water (H2O) splits to provide the H and OH needed to complete the resulting monosaccharides. Hydrolysis reactions commonly occur during digestion.

hydrolysis

when blood glucose levels rise, the pancreas secretes

insulin

The mouth, pancreas, and_____ are the parts of the digestive system involved in digestion of carbohydrates

small intestine

plant cells store glucose as _____long, branched or unbranched chains of hundreds or thousands of glucose molecules linked together. -All starchy foods come from plants. grains as richest source

starches

fructose

sweetest of all the sugars but has the same chemical formula as glucose

(the sugars) are sometimes called simple car-bohydrates

Monosaccharides and disaccharides

_____ is the sweetest of the disaccharides because it contains fructose, the sweetest of the monosaccharides. These sugars account for the natural sweetness of fruits, vegetables, and grains. To make table sugar, sucrose is refined from the juices of sugarcane and sugar beets, then granulated.

Sucrose

The dietary carbohydrate family includes:

-Monosaccharides: single sugars -Disaccharides: sugars composed of pairs of monosaccharides -Polysaccharides: large molecules composed of chains of monosaccharides

the three monosaccharides

-all have the same numbers and kinds of atoms—each contains 6 carbon atoms, 12 hydrogens, and 6 oxygens -The monosaccharides differ in their arrangements of the atoms. These chemical differences account for the differing sweetness of the monosaccharides. A pinch of purified glucose on the tongue gives only a mild sweet flavor, and galactose hardly tastes sweet at all. Fructose, however, is as intensely sweet as honey and, in fact, is the sugar primarily responsible for honey's sweetness.

the most important sugars in nutrition,

-glucose, fructose, galactose(these are monosaccharides ) -Maltose (glucose 1 glucose), Sucrose (glucose 1 fructose) Lactose (glucose 1 galactose)( these are disaccharides)

_____ are the structural parts of plants and thus are found in all plant-derived foods. Most dietary fibers are polysaccharides but dietary fibers differ from starches in that the bonds between their monosaccharides cannot be broken down by digestive enzymes in the body. For this reason, dietary fibers are often described as nonstarch polysaccharides.. Because dietary fibers pass through the body undigested, they contribute no monosaccharides, and therefore little or no energy.

Dietary fibers

_____ is the sweetest of the sugars. Curiously, fructose has exactly the same chemical formula as glucose—C6H12O6—but its structure differs. The arrangement of the atoms in fructose stimulates the taste buds on the tongue to produce the sweet sensation. Fructose occurs naturally in fruits and honey; other sources include products such as soft drinks, ready-to-eat cereals

Fructose

______ performs an important role, it stores glucose for future use. Glycogen is made of many glucose molecules linked together in highly branched chains When the hormonal message "release energy" arrives at a liver or muscle cell, enzymes respond by attacking the many branches of glycogen simultaneously, making a surge of glucose available.*

Glycogen

______ The combination of galactose and glucose makes the disaccharide lactose, the principal carbohydrate of milk. Known as milk sugar, lactose contributes half of the energy (kcalories) provided by fat-free milk.

Lactose

_____ is produced whenever starch breaks down. It also occurs during the fermentation process that yields alcohol. Maltose is only a minor constituent of a few foods, most notably barley.

Maltose

Glucose and galactose enter the cells lining the small intestine by _____

active transport

When they eat foods rich in _____ their bodies receive glucose for immediate energy and convert some glu cose into glycogen for reserve energy.

carbohydrates

The making of a disaccharide from two monosaccharides is an example

condensation

To make a disaccharide, a chemical reaction known as ______ links two monosaccharides together . A hydroxyl (OH) group from one monosaccharide and a hydrogen atom (H) from the other combine to create a molecule of water (H2O)

condensation

when the body is lacking glucose, fat fragments can combine to form

ketone bodies

(starches and fibers) are sometimes called complex carbohydrates.

polysaccharides

A chain of 10 monosaccharides linked together is called a

polysaccharides