Chapter 3: Chemistry of Life

Enzymes

Carbon and Bonding• What makes carbon so unique is the ability to

bond 4 times because it has 4 valence shell electrons.

• The majority of the time, carbon forms covalent bonds.

• There are many different types of bonds carbon can form.

Bonding

• What is bonding?

• What are the main types of bonding?

• What makes them different?

• So then, what’s the difference between a polar and a non-polar bond?

– List an example of each.

– Why then do oil and water not mix?

Hydrocarbons• Hydrocarbons are

compounds consisting of only hydrogen and carbon.

• They serve as a basis for petroleum, while not common in living organisms, many organic molecules in a cell consist of a region containing only H and C.

Organic Chemistry

• Organic chemistry is the study of carbon containing compounds. These compounds must also contain hydrogen to be considered organic.

• CO2, CO, and CaCO3, etc., for example, are not considered organic despite the fact that they contain carbon. The reason being, there is no hydrogen.

Carbon and Bonding

• Carbon also has the ability to form long chains, some of which contain double bonds.

• Butene, C4H10

• Carbon can also form ring structures as seen in benzene, C6H6.

Carbon and Bonding

• Additionally, ball shaped carbon containing compounds called “buckeyballs” they are C-60 and are called buckeyballs.

Carbon and Bonding

• The diversity of carbon allows a nearly endless supply of compounds to be made, and it is this reason that carbon plays such a large and important role in biology.

Chemical Reactions

• Reactants get converted into products.

• This obeys the Law of Conservation of Mass, and the Law of Conservation of Energy.

Metabolism

• The sum of all chemical reactions that take place in the organism.

• It is the way in which a cell manages its material and energy resources.

Pathways Within the Cell

• Anabolic:

• These are the build up pathways that use starting materials to build biologically useful molecules.

• Catabolic:• These are the

breakdown pathways that use energy stored in the bonds of starting materials to drive the synthesis of energetic molecules.

Anabolic Pathways

• Building proteins from amino acids we obtain from eating food.

Catabolic Pathways

• Forming ATP from Glucose.

• Glucose comes from the food we eat.

• ATP is the energy source for the cell.

Enzymes

• Enzymes are used by the cell to lower the activation energy required for a chemical reaction.

• All enzymes are proteins.

• They speed up chemical reactions.

Enzymes

• More specifically, within a cell, enzymes are proteins that bind to a specific substrate on which the enzyme acts forming an enzyme-substrate complex.

Enzymes

• The enzyme-substrate complex forms an “induced” (tight) fit between the enzyme and the substrate at the active site.

Things which affect enzyme function

• Temperature and pH denature the protein.

• Cofactors help an enzyme function.

– Often inorganic, metal ions are an example

• Coenzymes which are organic substances also help.

– Often organic, vitamins are an example

Things which affect enzyme function

• Inhibitors--slow or stop enzyme activity

– Competitive inhibitors--compete with substrate molecules for the active site of an enzyme.

– Non-competitive inhibitors--bind to a spot other than the active site altering the active site slowing a reaction.