Biology

Chapter 4.2                                                                                                                            Carbohydrates                                                                                                                                                     Concepts/Ideas/Facts:

1. carbohydrates are most abundant molecule in nature
2. consist of carbon, hydrogen, and oxygen in a 1:2:1 ratio (CH₂O)
3. Have roles in self recognition and immunity
4. Receptors function in cell-to-cell communication
5. Cells require carbohydrates as structural materials, energy storage forms, and transportable packets of energy

Definitions:

1.        CARBOHYDRATES – simple or complex molecules made up of H, C, and O. Sometimes called glycans.

2.        SUGARS – made up of at least two OH groups bonded to their carbon backbone and one aldehyde or one ketone group. Common types have a backbone of 5 or 6 carbons. Most dissolve easily in water.

3.        MONOMERS – small organic compounds that when bonded together form larger molecules called polymers

4.        POLYMERS – large organic compounds made from bonding together monomers

5.        MONOSACCHARIDES – made up of only one sugar unit and are the simplest carbohydrates. Simple sugars have multiple hydroxyl groups. Based on the number of carbons (e.g., 3, 4, 5, or 6) a monosaccharide is a triose, tetrose, pentose, or hexose, etc.

a.       glucose – blood sugar is the only sugar cells use directly (hexose)

b.      galactose – found in milk and yogurt (hexose)

c.      fructose – found in honey and fruit (pentose) and the sweetest sugar

6.        DISACCARIDES - consist of two sugar monomers (monosaccharides) covalently bonded  together.

a.       lactose (milk) – made up of glucose and galactose

b.      sucrose – the most plentiful sugar in nature – made up of glucose and fructose (table sugar)

c.       maltose - product of starch digestion = glucose + glucose

7.        OLIGOSACCARIDES – a few sugars monomers (monosaccharides) covalently bonded together

8.        POLYSACCARIDES – straight or branched chains of many sugars bonded together (monosaccharides or disaccharides). Sometimes called “complex” carbohydrates. Different polysaccharides have different covalent bonding patterns between their glucose units (monomers) which change their properties.

a.        Starch – glucose put together at an angle which causes them to coil like a spiral staircase. The OH groups project outward from these coils which makes it easy for enzymes to break them down. Insoluble in water. Must be digested by amylase before they can be used by cells. Plants convert excess glucose into starches for storage.

b.      Cellulose – glucose chains stretch side by side and hydrogen bond at OH groups. The hydrogen bonds stabilize the chain into tight bundles that form long fibers. Cellulose is the most abundant polysaccharide in nature.

c.       Glycogen – glucose chains formed of 8 to 12 molecules are the principle storage form of glucose, sometimes known as “animal starch”. Animals convert excess glucose not converted to glycogen into fat!

9.        ISOMERS – compounds with a single chemical formula but different forms.

10.    STARCH – polymer of glucose (sugar)

11.    CHITIN - Chitin is the second most abundant polysaccharide in nature (after cellulose). Main constituent of the shells of arthropods. It is made up of glucose chains and has a Nitrogen containing group attached to its glucose units. Induces burns and wounds to skin to heal faster.

12.    CARBOXYL GROUP – written  −COOH  or structural formula

                                              −  C − OH

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3D WEBSITE FOR MOLECULES! SEE THE CARBOHYDRATES!