Question

. Match the term with the proper description. (a) Fatty acid (b) Triacylglycerol (c) Phospholipid (d) Sphingosine (e) Phosphoglyceride (f) Sphingomyelin (g) Glycolipid (h) Cerebroside (j) Cholesterol 1\. Membrane lipids with a glycerol backbone 2\. Phospholipid especially common in nerve cells 3\. The simplest glycolipid 4\. Derived from sphingosine and found in all membranes 5\. Chains of hydrogenbearing carbon atoms 6\. Complex glycolipids 7\. A complex alcohol backbone for membrane lipids 8\. Major class of membrane lipids 9\. Steroid-based lipid 10\. Storage form of fatty acids

Short answer

(a) 5, (b) 10, (c) 8, (d) 7, (e) 1, (f) 2, (g) 6, (h) 3, (j) 9.

Step-by-step solution

Identify Fatty Acid

A fatty acid is a chain of hydrogen-bearing carbon atoms, which corresponds to option 5.

Match Triacylglycerol

A triacylglycerol is the storage form of fatty acids, which matches with option 10.

Determine Phospholipid

Phospholipids are a major class of membrane lipids and match with option 8.

Identify Sphingosine

Sphingosine is a complex alcohol backbone for membrane lipids and corresponds to option 7.

Match Phosphoglyceride

Phosphoglycerides are membrane lipids with a glycerol backbone, which is described by option 1.

Explain Sphingomyelin

Sphingomyelin is a phospholipid especially common in nerve cells, matching option 2.

Define Glycolipid

Complex glycolipids are described by option 6.

Match Cerebroside

Cerebroside is the simplest glycolipid, which matches option 3.

Describe Cholesterol

Cholesterol is a steroid-based lipid, corresponding to option 9.

Key concepts

Fatty Acids

Fatty acids are the building blocks of fats in our bodies and in the food we eat. They are essentially long chains of carbon atoms bonded to hydrogen atoms. The length of these chains can vary, and they can be either saturated or unsaturated. Saturated fatty acids have no double bonds between the carbon atoms, making them generally solid at room temperature, like butter. Unsaturated fatty acids have one or more double bonds, which introduce kinks in the chain, often making them liquid at room temperature, like olive oil.

• Saturated: Found in animal products and some plant oils.
• Unsaturated: Mostly found in vegetables, nuts, and seeds.

These molecules are vital as they serve as a major source of energy, and they are also used by the body to build cells and produce certain hormones.

Phospholipids

Phospholipids are a major class of lipids essential for life, as they form the fundamental building blocks of cell membranes. Each phospholipid molecule is composed of two fatty acid tails and a phosphate group head connected by a glycerol molecule. The unique structure of phospholipids allows them to form bilayers, which serve as barriers in cell membranes and create the necessary environment for cellular function.
The phosphate "head" is hydrophilic (water-attracting), while the fatty acid "tails" are hydrophobic (water-repelling), allowing phospholipids to orient themselves with tails inward, shielding from water, and heads outward.

• Phospholipids create the flexible and semi-permeable nature of cell membranes.
• They are involved in cell signaling and membrane structure dynamics.

This dual nature is critical for the formation of cellular compartments and the complex processes that occur inside cells.

Glycolipids

Glycolipids are lipids with a carbohydrate attached, playing a critical role in cellular recognition and communication. The carbohydrate parts face the outside of the cell, forming part of the glycocalyx, which is important for interactions with the environment and other cells. Glycolipids are primarily found on the outer layer of the cell membrane, making them involved in signaling and immune responses.

• They assist in cell recognition and adhesion.
• Play a role in the stability of the cell membrane.

Cerebrosides and gangliosides are types of glycolipids, contributing to the complexity of cell surface structures, especially in nerve cells, where they are abundant.

Cholesterol

Cholesterol is a type of lipid known as a sterol, which is integral to cell membrane structure and function. Despite its negative reputation related to heart disease, cholesterol is crucial for several bodily functions. It helps to stabilize cell membranes, making them less permeable and more flexible. Cholesterol is also a precursor for the synthesis of steroid hormones, bile acids, and vitamin D.

• Essential for membrane fluidity and permeability.
• Required for the production of vital hormones such as cortisol and estrogen.
• Aids in digestion through bile acid formation.

Cholesterol circulates in the bloodstream attached to proteins called lipoproteins, which are categorized as high-density (HDL) or low-density (LDL) based on their density, with HDL considered the "good" cholesterol and LDL often labeled as "bad" cholesterol due to its association with atherosclerosis.