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Chemistry of Life

Chemistry of Life

Description:
  • To review the structure of atoms and the formation of chemical bonds.
  • To examine hydrogen bonding in water and the properties that his allows.
  • To discuss the structure and function of the four different organic molecules.
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Tutorial

Atomic Hook-Ups - Types of Chemical Bonds

This video is created by Crash Course. It focuses on non-polar covalent, polar covalent and ionic bonding. The information of bond energy is not important for AP Biology.

Bonding occurs as atoms attempt to fill their outermost energy level which allows the atom to become stable. The number of valence electrons, electrons in the outer shell, determine whether they will form an ionic or covalent bond. Typically when a metal and a nonmetal combine, like NaCl, one atom will give an electron and one will take forming an ionic bond. When two nonmetal bond they usually share electrons creating covalent bonds.

Representing Structures of Organic Molecules

This is from Khan Academy.

Common Carbohydrates

Carbohydrates can exist as monosaccharides, disaccharides or polysaccharides (saccharides means sugar). The most commonly discussed monosaccharide is glucose.  There are two types of glucose: alpha and beta. The difference between these is the placement of the H and OH on their first carbon.  Fructose is also a common monosaccharide which the same molecular formula as glucose but a different arrangement. Molecules with the same formula but different shapes are called isomers and they may exhibit very different properties.

a + b glucose

 

a + b glucosep

Some common disaccharides include sucrose (table sugar) which is made up of glucose and fructose, lactose (milk sugar) which is made up of glucose and galactose, and maltose (from the breakdown of starch) which is two glucose.

There are 4 major glucose polymers that are important to biology.  Starch and glycogen are both made of alpha glucose and are responsible for energy storage: starch in plants, glycogen in animals.  Cellulose and chitin are both made from beta glucose and are structural molecules: cellulose in plant cells walls and chitin in fungi cell walls and exoskeletons. 

Lipids

Three major classes of lipids include triglycerides, phospholipids and steroids.  Steroids all have 4 carbon rings attached to one another. Some common examples include cholesterol, estrogen and testosterone. 

 

Proteins

There are many different types of proteins  which are categorized by their function. These functions include storage (ovalbumin in egg whites), structure (keratin in hair), transport (hemoglobin in RBC), defense (antibodies), and enzymes (amylase which helps digest carbohydrates).

There are 4 levels to protein structure.  The first is primary and is simply the order of the amino acids.  Secondary structure is the 3D shape that is caused by the hydrogen bonds that form between the amino group of one amino acid and the carboxyl group on another.  The two possible shapes are alpha helix (spiral) or beta pleated sheets.  Tertiary structure are added 3D shapes that may cause the protein to look globular.  These can be caused by ionic or hydrogen bonds between R groups, or when hydrophobic r groups move towards the center of the protein.     Quaternary structure is when multiple peptide chains come together.