Question

What are the subunits of a triglyceride? What is the difference between a saturated and an unsaturated fatty acid? What are the functions of fats in the body? (pages \(31-33\) )

Short answer

The subunits of a triglyceride consist of three fatty acid chains attached to a glycerol backbone. Saturated fatty acids have no double bonds between carbon atoms and are solid at room temperature, while unsaturated fatty acids have one or more double bonds, causing kinks in the chains and making them liquid at room temperature. Fats have several functions in the body, including energy storage, insulation and protection, structural components for cell membranes and hormones, carrier of fat-soluble vitamins, and a source of essential fatty acids.

Step-by-step solution

Subunits of a Triglyceride

A triglyceride is a type of lipid (fat) molecule found in the body. It consists of three fatty acid chains attached to a glycerol backbone. The fatty acid chains can be either saturated or unsaturated. The fatty acids and the glycerol molecule make up the subunits of a triglyceride.

Saturated vs Unsaturated Fatty Acids

Fatty acids are chains of carbon and hydrogen atoms. The main difference between saturated and unsaturated fatty acids lies in the presence of double bonds between carbon atoms in their molecular structure. Saturated fatty acids have no double bonds between the carbon atoms - they are saturated with hydrogen atoms. This results in a straight chain that can pack closely together, making them solid at room temperature (e.g., butter and lard). In contrast, unsaturated fatty acids have one or more double bonds between carbon atoms. These double bonds create kinks in the fatty acid chain, preventing them from packing closely together and remaining liquid at room temperature (e.g., vegetable oils).

Functions of Fats in the Body

Fats have several important functions in the body: 1. Energy storage: Fats are an efficient way to store energy, as they provide 9 kcal per gram, which is more than double the energy provided by carbohydrates and proteins. The body can store excess calories as triglycerides in adipose tissue for later use. 2. Insulation and protection: Fats in the form of adipose tissue help insulate the body and reduce heat loss. Moreover, they also provide a protective cushion for internal organs, such as the heart and kidneys. 3. Structural component: Fats are essential components of cell membranes and various hormones, contributing to the integrity and functionality of cells and tissues. 4. Carrier of fat-soluble vitamins: Fats play a vital role in transporting fat-soluble vitamins, namely vitamins A, D, E, and K. These vitamins are essential for maintaining various body functions, such as blood clotting and immune system. 5. Source of essential fatty acids: Fats are the primary source of essential fatty acids, such as omega-3 and omega-6. These fatty acids cannot be produced by the body and must be obtained through the diet. They play critical roles in brain development, inflammation regulation, and cardiovascular health.

Key concepts

Saturated Fatty Acids

Saturated fatty acids are a type of fatty acid chain where every carbon atom is "saturated" with hydrogen atoms. This means there are no double bonds in the chain of carbon atoms. Because of this structure, the chains are straight and can pack closely together. This close packing explains why saturated fatty acids are typically solid at room temperature.

Common sources of saturated fatty acids include:

• Butter
• Cream
• Cheese
• Lard

These are often found in animal products.
This characteristic makes them useful in food products where a solid form is desired, such as in spreads and baked goods.

Unsaturated Fatty Acids

Unsaturated fatty acids differ from saturated fatty acids by the presence of one or more double bonds between carbon atoms. These double bonds cause kinks in the fatty acid chain, preventing tight packing and making them liquid at room temperature.

Unsaturated fatty acids are divided into two types:

• Monounsaturated fatty acids (MUFAs): These have one double bond. Olive oil is a common source.
• Polyunsaturated fatty acids (PUFAs): These have two or more double bonds. Examples include sunflower oil and fish oils.

These oils are often seen as healthier dietary fats compared to saturated fats and are associated with better heart health.

Functions of Fats

Fats are vital for numerous bodily functions, playing roles that are crucial to our wellness and survival. Here are some key functions:

• Energy Storage: Fats store more energy than carbohydrates or proteins. At 9 kcal per gram, they provide more than double the energy compared to other macronutrients.
• Insulation and Protection: Fats help insulate the body, reduce heat loss, and act as cushioning for vital organs.
• Structural Components: They are integral components of cell membranes and are necessary for creating hormones that regulate body processes.
• Vitamin Carrier: Fats aid in the absorption and transport of fat-soluble vitamins such as A, D, E, and K.
• Essential Fatty Acid Source: They supply essential fatty acids needed for brain health and regulating inflammation.

Overall, fats are not just sources of energy. They are fundamental in maintaining the body's integrity and supporting numerous bodily processes.

Energy Storage

Fats are an excellent means for the body to store energy. Unlike carbohydrates and proteins, which offer only 4 kcal per gram, fats provide 9 kcal per gram.

This energy efficiency allows the body to compactly store large energy reserves that can be used during times of caloric deficit or increased physical activity. In adipose tissue, triglycerides are stored for prolonged periods, ensuring a readily available energy supply when the body requires it. This makes fat a critical component in an energy management system that supports extended physical exertion and survival without constant food intake.

Essential Fatty Acids

Essential fatty acids are crucial nutrients that the body cannot synthesize on its own. These must be obtained through dietary means for the body to function properly.

The two most notable essential fatty acids are omega-3 and omega-6 fatty acids. These play important roles in:

• Brain development and function
• Regulating inflammation and promoting heart health
• Ensuring skin barrier function and cellular health

Sources of essential fatty acids include fish, flaxseeds, and walnuts for omega-3, and plant oils such as sunflower oil and safflower oil for omega-6. It's important to consume these fats in balanced proportions to maintain optimal health.