Chapter 3: The Molecules of Life – Study Notes

Chapter 3: The Molecules of Life

Introduction

This chapter explores the fundamental molecules that constitute living organisms, focusing on the structure and function of biological macromolecules. Understanding these molecules is essential for grasping how life operates at the molecular level.

DNA Structure and Diversity

Similarity of DNA Across Species

• DNA (Deoxyribonucleic Acid) is the hereditary material in almost all living organisms.

• The basic structure of DNA is nearly identical in all species, from mosquitoes to elephants.

• Differences between species arise from the specific sequence and arrangement of nucleotides (the building blocks of DNA).

• Nucleotides are composed of a sugar, a phosphate group, and a nitrogenous base.

• Example: The DNA of an elephant and a mosquito is made of the same chemical components, but the order of nucleotides determines the organism's traits.

Biology and Society: Lactose Intolerance

Lactose and Its Digestion

• Lactose is the main sugar found in milk.

• Lactose intolerance is the inability to properly digest lactose due to insufficient production of the enzyme lactase.

• Individuals with lactose intolerance may experience digestive discomfort after consuming dairy products.

Addressing Lactose Intolerance

• Lactose intolerance can be managed by:

  • Avoiding lactose-containing foods such as milk, ice cream, and some cheeses.

  • Consuming lactase enzyme supplements (lactase pills) along with food to aid in lactose digestion.

• Example: A person with lactose intolerance may choose lactose-free milk or take lactase pills before eating ice cream.

Additional info: Lactose intolerance is more common in certain populations and is an example of how genetic variation can affect metabolism and dietary needs.