1.3. Describe the structure and function of organic molecules

This guide will help you answer 1.3. Describe the structure and function of organic molecules.

Organic molecules form the basis of life. They contain carbon atoms, usually bonded with hydrogen, oxygen, nitrogen, and other elements. Understanding the structure and function of these molecules is key in health and social care, as they play essential roles in biological processes. In this guide, we cover the different types of organic molecules, their structure, and their specific functions.

Types of Organic Molecules

There are four major types of organic molecules in living organisms:

• Carbohydrates
• Lipids
• Proteins
• Nucleic Acids

Each type serves a unique purpose and has a distinct structure.

Carbohydrates

Structure:
Carbohydrates are organic molecules made up of carbon (C), hydrogen (H), and oxygen (O), typically in a ratio of 1:2:1. They are classified into three categories based on their size:

• Monosaccharides are simple sugars, such as glucose and fructose.
• Disaccharides are made of two monosaccharides joined together, like sucrose (table sugar).
• Polysaccharides are larger, complex carbohydrates formed by linking many monosaccharides, such as starch and glycogen.

Function:
Carbohydrates are the body’s main source of energy. Cells break them down into glucose, which provides fuel for cellular activities. Polysaccharides such as glycogen act as energy storage, while cellulose (found in plants) provides structural support.

In health, an imbalance in carbohydrate consumption can lead to conditions such as diabetes or obesity.

Lipids

Structure:
Lipids are a diverse group of organic molecules that are hydrophobic, meaning they do not dissolve in water. They consist primarily of carbon, hydrogen, and a small amount of oxygen. The main types of lipids include:

• Fats and Oils – made of glycerol and three fatty acids. These are called triglycerides.
• Phospholipids – similar to triglycerides, but contain a phosphate group.
• Steroids – such as cholesterol, with a structure of four fused carbon rings.
• Waxes – long-chain fatty acids bonded to alcohols.

Function:
Lipids are essential for storing energy, with fats providing more than twice the energy per gram compared to carbohydrates. They are vital for building cell membranes (phospholipids) and insulating the body.

Steroids, like cholesterol, are used to produce certain hormones such as oestrogen and testosterone. In health care, it’s crucial to manage lipid levels, as high cholesterol contributes to heart disease.

Proteins

Structure:
Proteins are made of smaller units called amino acids. Amino acids contain carbon, hydrogen, oxygen, nitrogen, and sometimes sulphur. There are 20 different amino acids, and they join together in long chains to form polypeptides. These chains fold into specific three-dimensional shapes to create functional proteins.

Function:
Proteins are vital for nearly every biological process. Their functions include:

• Structural roles – collagen, found in skin and connective tissue.
• Transport – haemoglobin carries oxygen around the body.
• Enzymatic activity – enzymes like amylase speed up chemical reactions.
• Immunity – antibodies fight off infections.

Proteins are needed for growth, repair, and maintenance of our bodies. A lack of protein can cause muscle weakness, delayed healing, and weakened immunity.

Nucleic Acids

Structure:
Nucleic acids are large organic molecules made of smaller units called nucleotides. Each nucleotide consists of three parts:

• A sugar molecule (deoxyribose in DNA or ribose in RNA)
• A phosphate group
• A nitrogen-containing base (adenine, thymine, cytosine, guanine in DNA; and uracil replacing thymine in RNA)

The two main types of nucleic acids are:

• DNA (Deoxyribonucleic acid) – a double-stranded helix.
• RNA (Ribonucleic acid) – usually single-stranded.

Function:
DNA carries genetic information essential for cell functioning, growth, and reproduction. It holds the instructions to produce proteins. RNA helps transfer this information to ribosomes for protein synthesis.

In the context of health, mutations or damage to DNA can lead to genetic disorders or cancers.

How Organic Molecules Work Together

These four types of organic molecules do not work in isolation. They interact to maintain life. For example:

• Proteins (enzymes) help break down carbohydrates into glucose, which cells use for energy.
• Lipids form part of the structures that carbohydrates and proteins pass through, such as cellular membranes.
• DNA gives instructions for making enzymes, ensuring all processes function correctly.

This interdependence highlights the importance of a balanced diet containing all these molecules.

Organic Molecules and Health and Social Care

A thorough understanding of organic molecules is necessary in health and social care. For example, monitoring blood glucose levels helps manage diabetes. Care workers may advise clients about protein-rich diets to promote healing or educate about reducing saturated fats to prevent heart disease.

In practice, ensuring a person receives these essential nutrients supports their physical and mental health.

Final Thoughts

Organic molecules are fundamental to life. Carbohydrates provide energy, lipids store energy and form membranes, proteins perform countless roles, and nucleic acids carry our genetic code. Together, they support the growth, repair, and overall function of the human body, making them a vital topic in health and social care settings.