Fundamental Biological Molecules: Water, Carbohydrates, Lipids, Proteins, DNA

Water: The Essential Solvent

Water constitutes approximately 80% of the human body and plays a crucial role in biological systems.

Role of Water as a Solvent

Water is an important solvent, a liquid in which substances (or solutes) are dissolved, forming a solution. In a solution, the solvent is typically present in a greater amount than the solute.

Metabolic reactions, which are vital for life, can only take place if the chemicals reacting are dissolved in water.

Other Vital Functions of Water

Water is also essential for other reasons, such as being the primary component of plasma, the liquid part of blood, facilitating transport throughout the body.

Carbohydrates: Energy & Structure

Carbohydrates include starches and sugars, and are composed of Carbon, Hydrogen, and Oxygen.

Types of Carbohydrates

• Simple Sugars (Monosaccharides)

  An example is glucose, which is made of 6 carbon, 12 hydrogen, and 6 oxygen atoms.

• Complex Sugars (Disaccharides)

  If two simple sugar molecules join together, they form a larger molecule called a complex sugar or disaccharide.

• Polysaccharides

  If many simple sugars join together, they form a very large molecule known as a polysaccharide.

  • Cellulose: Forms plant cell walls, providing structural support.
  • Starch: Serves as energy storage in plants.
  • Glycogen: The primary form of energy storage in animals.

Carbohydrate Metabolism & Storage

Plants utilize glucose in respiration to provide them with energy. They do not transport glucose directly around their bodies; instead, cells convert sucrose to glucose when needed.

Animals do not store starch. They store carbohydrates in the form of the polysaccharide glycogen. Only small quantities of glycogen can be stored, primarily in the cells of the liver and muscles.

Lipids: Fats, Oils & Energy Reserves

Lipids encompass fats and oils, which are crucial for energy reserves.

• Fats: Typically solid at room temperature.
• Oils: Typically liquid at room temperature.

Proteins: Building Blocks of Life

Proteins are made of long chains of smaller molecules called amino acids, joined end to end.

Some proteins are soluble in water, while others are not.

Comparing Essential Macronutrients

Elemental Composition

• Carbohydrates: Carbon (C), Hydrogen (H), Oxygen (O)
• Fats: Carbon (C), Hydrogen (H), Oxygen (O)
• Proteins: Carbon (C), Hydrogen (H), Oxygen (O), Nitrogen (N)

Basic Building Blocks

• Carbohydrates: Simple sugars (monosaccharides)
• Fats: Fatty acids and glycerol
• Proteins: Amino acids

Water Solubility

• Carbohydrates: Sugars are soluble
• Fats: Insoluble
• Proteins: Some are soluble, some are not

Primary Functions

• Carbohydrates: Easily available energy
• Fats: Long-term energy storage
• Proteins: Essential for making cells, enzymes, and can also be used for energy.

General Functions of Macronutrients

• Growth & Repair: Essential for building and maintaining tissues.
• Metabolism: The sum of chemical reactions within each living cell that provide energy for vital processes and for synthesizing new organic material.
• Structure: Provide structural components for cells and tissues.

DNA: The Blueprint of Life

DNA (Deoxyribonucleic Acid) is the chemical that makes up our genes and chromosomes. It is the material that we inherit from our parents.

DNA is made of two long strands, each with a series of bases arranged along it, forming a double helix structure.