Biochemical Reactions

Agenda

• Roles and summary of DNA
• Basics of a chemical reaction
• Types of reactions
• Enzymes

DNA has the genetic instructions for the sequence of amino acids in proteins.

RNA uses information from DNA to assemble the amino acids into proteins.

DNA is passed from parent cells to daughter cells when cells divide and from parents to offspring.

Reactions Objectives

• Distinguish between reactants and products
• Identify a chemical equation

The substances we have before a reaction occurs are reactants. The substances that form are products.

Example

• Burning of methane
• methane + oxygen yield carbon dioxide and water

The arrow shows the direction of the reaction.

The number in front of the formula tells you how many molecules are necessary.

Matter is conserved. If you start with four oxygens, you better end with four oxygens!

The same rules apply for biochemical reactions.

Biochemical reactions are chemical reactions that take place inside cells.

The sum of all biochemical reactions in an organism is called metabolism.

Two types of biochemical reactions

• Exothermic
• Endothermic

Catabolic reactions are exothermic reactions. They break down molecules into smaller units to release energy.

Anabolic reactions are endothermic. They involve building larger molecules from small pieces.

Examples?

Enzymes are biological catalysts that speed up these reactions.

Why?

• Concentration is too low
• Temperature is too low

Enzymes can be used repeatedly but only for specific reactions.

Enzymes work by lowering the activation energy of chemical reactions.

(activation energy is the energy needed to start the chemical reaction)