3.3 Biology

A disaccharide consists of two monosaccharides tied together by what kind of linkage?

A glycosidic linkage a covalent bond formed between two monosaccharides by a dehydration reaction

Monosaccharides come in multiples of what chemical formula?

CH2O

Monosaccharides, particularly glucose, are major nutrients, what do they do in cells?

Cells extract energy from glucose molecules by breaking them down in a series of reactions. The carbon skeletons of monosaccharides serve as raw material for the synthesis of other types of small organic molecules, such as amino acids. Monosaccharides that are not immediately used in these ways are generally incorporated as monomers into disaccharides or polysaccharides.

________________ are double sugars, consisting of two monosaccharides joined by a covalent bond

Disaccharides

Although a linear representation of sugars makes them easy to understand, in aqueous solutions, they actually do what?

Form rings; the most stable form of these sugars under physiological conditions

What is the most important monosaccharide? Describe its structure

Glucose: C6H12O6; central component in life It has a carbonyl group (=C=O) and multiple hydroxyl (OH) groups. THe location of the carbonyl group determines if it is aldehyde or ketose.

Name a few monosaccharides

Glycerdlehyde, glucose, ribose, fructose...

Name other disaccharides

Lactose (the sugar found in milk) Maltose (the sugar found in beer)

Simplest carbohydrate (monomer)

Monosaccharide; simple sugars the monomers from which more complex carbohydrates are built

Humans can also use starch but in a different way

Most animals, including humans, also have enzymes that can hydrolyze plant starch, making glucose available as a nutrient for cells, not a storage unit. Potato tubers and grains—the fruits of wheat, maize (corn), rice, and other grasses—are the major sources of starch in the human diet

What is the purpose of the polysaccharide?

Some polysaccharides serve as storage material, hydrolyzed as needed to provide sugar monomers for cells. Other polysaccharides serve as building material for structures that protect the cell or the whole organism. The structure and function of a polysaccharide are determined by its sugar monomers and by the positions of its glycosidic linkages. (so either storage or structural purpose)

What are the four polysacchrides, and what are their monomers?

Starch, Glycogen, Cellulose, and Chitin. First three have monomer glucose, while chitin has monomer glycoglucose...

What is the most important/common disaccharide?

Sucrose: table sugar It is made up of the monomers glucose and fructose Plants generally transport carbohydrates from leaves to roots and other nonphotosynthetic organs in the form of sucrose

Carbohydrates

Sugars and polymers of sugar

Carbonyl group in monosaccharides

The carbonyl group can be on the end of the linear sugar molecule, as in glucose, or attached to an interior carbon, as in fructose Thus glucose is an aldahyde (carbonyl outside), while fructose is a ketose sugar (carbonyl inside)

Polysaccharide

The polymer for carbs. They are macromolecules, polymers with a few hundred to a few thousand monosaccharides joined by glycosidic linkages

How is energy absorbed from disaccharides?

They must be broken down into monosaccharides by the body Lactose intolerance is a common condition in humans who lack lactase, the enzyme that breaks down lactose. Solution could be to take lactase supplements.

Starch (storage polysaccharide)

This is the polysaccharide used for STORAGE in plants. Plants store starch, a polymer of glucose monomers joined by glycocidic linkages, as granules within cell. Because glucose is a major cellular fuel, starch represents stored energy. The sugar can later be withdrawn by the plant from this carbohydrate "bank" (starch) by hydrolysis, which breaks the bonds between the glucose monomers. Alpha (cis) helical (but not highly branched)

Glycogen (storage polysaccharide)

a polymer of glucose that is like amylopectin but more extensively branched used by humans and animals as stored energy just as starch does for animals. Located in liver and muscles. Helical. This stored fuel cannot sustain an animal for long, however. In humans, for example, glycogen stores are depleted in about a day unless they are replenished by eating. This is an issue of concern in ultra-low-carbohydrate diets, which can result in weakness and fatigue. Alpha (cis) helical

Cellulose (structural polysaccharide)

a polymer of glucose; major component of cell walls; produced by the 100s and billions of tons annually by plants; most common compound on earth Like starch, cellulose is a polymer of glucose with 1-4 glycosidic linkages, but the linkages in these two polymers differ. The difference is based on the fact that there are actually two slightly different ring structures for glucose. (refer to figures to see difference in structure between starch and ceullulose) Beta pleated (trans)- ribbon structure; flat and straight effecting structure

Carbohydrates also include __________________ called __________________, polymers composed of many sugar building blocks joined together by ______________ reactions

macromolecules polysaccharides dehydration

Chitin

the carbohydrate used by arthropods (insects, spiders, crustaceans, and related animals) to build their exoskeletons Chitin is also found in many fungi, which use this polysaccharide as the building material for their cell walls. Chitin is similar to cellulose except that the glucose monomer of chitin has a nitrogen-containing attachment. Beta pleated (trans)- ribbon structure; flat and straight effecting structure

Hexose

6 carbon sugars like glucose, fructose. Tirose and pentose is also common. Ose ending is synonymous with sugar.