Molecules of Life Assignment

Introduction: Many molecules are critical to organism function. Scientists are interested in understanding the properties of biological molecules in order to recreate them in a laboratory environment. The goal is to mimic their structure and function to apply them to bioengineering, nanotechnology, environmental sciences, food sciences, health and medicine.
Purpose: To research and understand a molecule of biological interest and to relate the role of the molecule to its chemical and physical properties.
Choose a Molecule – Phospholipids
Procedure:
1.) Explain a biological role of the molecule. How is it important to the successful function of the organism?

Phospholipids play an extremely important role in molecules as cells could not exist without them. Phospholipids make up the lipid bilayer of cell membranes, they are also an important structural feature of cells. Furthermore, phospholipids are unique as they are also amphipathic molecules which means they contain both hydrophilic and hydrophobic regions. The hydrophilic region is the polar head group and the hydrophobic region is the fatty acid tail. In addition, the hydrophilic end of a phospholipid faces outward towards the water and the hydrophobic fatty acid tails face towards each other. Without phospholipids there would be no cell membrane which defines the inside from the outside of the cell and determines whether a particle can pass through it or not. Therefore, phospholipids are vital to the successful function of an organism.

2.) Determine the chemical and physical characteristics of the molecule.

Phospholipids have two distinct chemical and physical regions, hydrophobic non-polar fatty acid region and the hydrophilic polar head region, both have different chemical properties equally important to the function of the molecule. The top of the molecule also known as the head group, consists of polar and charged chemical groups that can easily dissolve in water. However, the tail of the molecule consists of two large hydrophobic fatty acid chains, which cannot interact with water. When in water the molecules will orient themselves such that the hydrophilic head groups interact with the aqueous solution, while the hydrophobic tails group together to become positioned away from the water thus creating a membrane.

3.) Include a diagram of the chemical structure and either a ball and stick or space filling diagram.

Analysis:
1) Describe how the physical characteristics (size and shape) of your molecule relate to its function.

The physical characteristics relate to the function of the phospholipid as it must be big enough that it won’t dissolve in water, but small enough to allow nutrients and waste to enter and exit the cell by passing through the membrane. They control the passage of particles going through the bilayer. If a particle is too big, then it cannot enter. However, the particle may get help from a protein carrier to help pass through the bilayer into the cell. Phospholipids also aid in the structural support of the cell as mentioned before, they make up the cell membrane, acting as the cells permeable backbone.

2) List the functional groups on your molecule.
The functional groups of a phospholipid molecule are…
Polar unit
Phosphate group
Glycerol
Two fatty acid chains

3) How do the functional groups influence…
a) Solubility
The hydrophilic head, polar unit and phosphate group are very attracted to water and other such aqueous solutions like intercellular and extracellular fluids. The two fatty acid chains are hydrophobic and therefore not soluble at all.
b) Reactivity
Phospholipids aren’t very reactive as they make up cell membranes. It