enzymes

Non-spontaneous reactions require energy input, with spontaneity determined by the change in free energy.
Free energy graphs illustrate energy changes throughout reactions.

Enzymes, such as lactase, interact with substrates to form products, either through degradation or synthesis.
Example: In the lab, OMPG (a lactose substitute) is converted by lactase, resulting in a color change from colorless to yellow (OMP).

The rate of reaction can be determined by measuring the time it takes for the color change (clear to yellow) to occur.
A spectrophotometer is used to measure the absorbance, which relates to color change over time.

The x-axis represents time, while the y-axis tracks energy changes during the reaction.
A steeper slope on a graph indicates a faster reaction rate, while a flatter slope suggests a slower reaction.
Without lactase, reactions proceed very slowly, resulting in minor changes over time.

Enzymes significantly increase the speed of reactions, depicted by a steep slope on energy change graphs.
Optimal conditions affect enzyme efficiency; extreme temperatures can denature enzymes, breaking hydrogen bonds crucial for enzyme structure.

Amino acids are the building blocks of proteins, and understanding their structure is vital.
The primary structure consists of a sequence of amino acids, while secondary structures include configurations like alpha helices and beta sheets.
Tertiary structure describes the overall 3D structure of a single polypeptide, while quaternary structure involves multiple polypeptide chains.
Each structural level is important for a protein's functionality; without proper folding and structure, reactions will not occur efficiently.

Enzymes have evolved to facilitate reactions that would not occur at biologically relevant speeds without them.
Understanding these concepts is critical for exams, focusing on enzymes, substrate interactions, and energy changes.

Topics covered include biochemical molecules such as amino acids, proteins, lipids, carbohydrates, and nucleic acids.
Students should be prepared to identify biochemical structures and understand how they connect to overall biological processes.
For the upcoming lab exam, focus on understanding figures and graphs rather than perfection in presentation.