Chemical Basis of Life

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A series of free High School Biology Video Lessons.

Enzymes
Enzymes are proteins that catalyze chemical reactions by facilitating the positioning of molecules. In biochemical pathways, sequences of enzymes form a chain of chemical reactions. Enzymes, like all catalysts, lower the activation energy of a reaction

The description and mechanistic functions of enzymes.
This video explains how enzymes are used to break down substrates. The correct shape of the active site allows a key/lock fit between the enzyme and the substrate. The enzyme catalase is used to break down hydrogen peroxide. The importance of cofactors and coenzymes is emphasized. Competitive and allosteric inhibition is also included. Proteins
Proteins, also known as polypeptide chains, are macromolecules of linked amino acids. Proteins are types of organic compounds that, among other things, store energy and form enzymes. Proteins have several levels of structure. On their primary structural level, they resemble neat chains, while on their tertiary level they resemble tangled messes.
The description and importance of proteins.
This video explains the structure and importance of proteins. It describes how proteins are created from amino acids connected by dehydration synthesis. It shows the importance of chemical properties in the R-groups of individual amino acids in the polypeptide. It explains the four levels of protein folding and gives you an opportunity to fold proteins of your own using the game Foldit: Nucleic Acid
Nucleic acids are long chains of monomers (nucleotides) that function as storage molecules in a cell. Nucleotides are composed of sugar, a phosphate group, and a nitrogenous base. ATP, DNA and RNA are all examples of nucleic acids.
The description and mechanistic functions of nucleic acids.
This video explains the importance and structure of nucleic acids. It begins with an introduction to DNA and RNA. It then describes the important parts of a nucleotide and shows how they are connected through covalent and hydrogen bonding.