BIOL 2051 Chapter Notes - Chapter 3: Chemical Polarity, Monosaccharide, Disaccharide
2 May 2018
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Chapter 3 Notes
3.1 The Carbon Atom and Carbon-Containing Molecules
• Key property of carbon: ability to form multiple covalent bonds with other atoms
• Mostly form covalent bonds in living organisms
o With hydrogen, oxygen, nitrogen, and sulfur
• Carbon in occurs in multiple forms: creates molecular diversity
o Linear
o Ring
o Highly branched
• Hydrocarbons: molecules made of entirely C-H or C-C bonds
o Also hydrophobic: not soluble
• When carbon forms a polar covalent bond it becomes hydrophilic and soluble in water
• Carbon is stable in temps associated with life
• Shorter bonds = stronger = more stable compared to longer bonds
• Functional Groups: a group of atoms that have characteristics that are important for
function
o All exhibit similar chemical properties
o
3.2 Synthesis and Breakdown of Organic Molecules
• Macromolecules are composed of thousands of atoms
• Important macromolecules are formed by linking together many small molecules called
monomers
o Monomers: 1
o Polymer: more than 1
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• Monomers polymers occur through dehydration synthesis
o Water molecule is broken
• Hydrolysis reaction: water is added in order to break the chain
3.3 Overview of Four Major Classes of Organic Molecules Found in Living Cells
• All forms of life have organic molecules and macromolecules
• Four Major Classes
o Carbohydrates
o Lipids
o Proteins
o Nucleic Acids
3.4 Carbohydrates
• Composed of Carbon, Hydrogen, and Oxygen
• Usually linked to a carbon atom, hydrogen or an –OH functional group
• Sugars = simple carbohydrates; polysaccharides = large macromolecules
• Simple Carbohydrates
o Simplest monomers = monosaccharides
o Most common type contain 5 carbons (pentoses) or 6 carbons (hexoses)
▪ Important pentoses: RNA and DNA
▪ Common hexoses: galactose, glucose, and fructose
• Similar formula of C6H12O6 but are arranged differently
(isomers)
• Can exist in linear but typically are in rings
o Ring is formed with oxygen between carbons 1 and 5
o Hydrogen and –OH groups can lie either below or above
the plane of the ring
• Glucose and galactose differ in position of the –OH group attach
toe carbon 4
• Fructose has two carbons outside the main ring
•
• Out of the 3, glucose plays the most important role
o Ex. Glucose is soluble: can be transported across cell
membranes
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▪ Once inside, enzymes break down the glucose and
released the energy stored in the chemical bonds
• Then stored in bonds of ATP (adenosine
triphosphate)
o Provides energy for a variety of
cellular processes
o Monosaccharides form disaccharides through dehydration synthesis/reaction
▪ Bond formed through dehydration synthesis: glyosidic bond
▪ Disaccharide = 2 sugars (monosaccharides) that are linked together
• Some disaccharides are sucrose or table sugar
o Composed of glucose and fructose
o Sucrose is a major transport form of sugars in plants
• Linking of monosaccharides involve the removal of an –OH group
from one monosaccharide and a hydrogen atom from the other
o This gives rise to water and covalently bonds the two
sugars together through an oxygen atom
• The energy stored in the bonds can be used to perform different functions that support
life
o Ex. Synthesis of new molecules, growth, digestion, locomotion, etc.
• Monosaccharides that are linked together form long polymers called polysaccharides
o Means many sugars
o Polysaccharides Include
▪ Starch: Found in plants
▪ Glycogen: Present within certain types of animal cells
▪ Cellulose: Found in the cell wall (plant)
▪ Peptidoglycans: Found in cell wall (bacteria)
▪ Chitin: Found in the cell wall of fungi and in the exoskeleton of insects
and arthropods
▪ Glycosaminoglycan: Polysaccharides that are found in the connective
tissues and surrounding cells in animals
• Starch, glycogen, and cellulose are composed of glucose molecules
that are linked together in long chains
o Branching between the 3 differ
o May contain nitrogen groups like amino acids
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Document Summary
3. 2 synthesis and breakdown of organic molecules: macromolecules are composed of thousands of atoms. 3. 3 overview of four major classes of organic molecules found in living cells: all forms of life have organic molecules and macromolecules, four major classes, carbohydrates, lipids, proteins, nucleic acids. In starch and glycogen it"s formed between carbons 1 and 4 and 1 and 6: high branching in glycogen contributes to the solubility in animal tissues, ex. Muscle: creates a more open structure in which many hydrophilic . 3. 5 lipids: are hydrophobic and composed mainly of hydrogen and carbon atoms (some oxygen, defining feature: nonpolar and poorly soluble in water. Include triglycerides, phospholipids, steroid, and waxes: triglycerides: consists of 1 glycerol and 3 fatty acids (referred to as fats, a 3-carbon molecule with 1 oh group bonded to each carbon. Cholesterol: common structure: have 4 rings and share a common ring structure, waxes: are secreted onto the surface of plants and animals, ex.
