Making up the building blocks for all the structures and functions of the living cells, Lipids are hydrocarbon-possessing molecules. From supplying the required energy to the body to metabolizing the hydrocarbons for release of sufficient energy, Lipids are important components to consider. Thus, with some basic information and important pointers, we are about to learn the values associated with Lipids including its definition, features, major classification, purpose, all supported with the lipids multiple choice questions and answers pdf section. Now, let us deep-drive into the topic by understanding what are lipids. 

A Basic Idea of Lipids with Examples

Lipids are the backbone to generating energy to the body, as well as the fundamental support to the body structures. Monoglycerides, Waxes, Fats, Sterols, Oils, Triglycerides, and even Vitamins such as K, E, A and D are said to be lipids. In Chemistry and Biology, Lipids are defined as macro-biomolecules that are insoluble in water but soluble in non-polar mixtures like the Chloroform. The 3 major functions of Lipids include the following: 

  • Lipid Energy storage and release

  • Lipid Signalling for internal cellular responses

  • Structural component to a cell membrane 

Major Classification of Lipids

As per the norms of Lipid Metabolites and Pathways Strategy (Lipid MAPS), there are 8 categories or types of lipid molecules. Let us get a brief understanding of each type from the following pointers:

  1. Sphingolipids: Consisting of a sphingoid base backbone and long-chain fatty acyl CoA with the de-novo synthesis of the amino acid Serine, Sphingolipids are complicated macro-molecules. Found in a few living mammals, gangliosides and cerebrosides are the 2 general examples of Sphingolipids. 

  2. Prenols: Created from the mevalonic acid (MVA) pathway, Prenols are synthesized from dimethylallyl diphosphate and isopentenyl diphosphate, which are the 2 major five-carbon-unit precursors. Carotenoids, Vitamin E,  Hydroquinones and Vitamin K are some of the examples of Prenols. 

  3. Glycerophospholipids: As an omnipresent lipid, Glycerophospholipids are the key structures to a cell’s lipid layering. They help in cell metabolism. Several neurological conditions are caused due to the alterations in Glycerophospholipids found in the brain. 

  4. Polyketides: Propionyl and Acetyl synthesis lead to the formation of Polyketides. These molecules are known for their huge range of diversity and are found in sources such as marine beds, bacteria, animals, and in some fungal areas. Polyketides play an important role as an anti-cancer and anti-microbial agent.  

  5. Sterols: Synthesized from the liver of mammals, Sterols are significant elements of the lipid membrane. Steroids, Bile acids and the derivatives of Cholesterol are the best examples to Sterols. 

  6. Fatty Acids: A hydrocarbon component that ends with a carboxylic group is that of Fatty acids. They are the building blocks to producing other complex biological lipid structures. Docosahexaenoic acid is a good example of Fatty acid, which is associated with sight. 

  7. Saccharolipids: The compatibility of the bilayers in Saccharolipids, takes credit from its major sugar backbone. Acylated glucosamine is the precursor Saccharolipids, the precursor for Lipid A (gram-negative bacteria).

  8. Glycerolipids: Present with mono-, di-, and tri-substitute glycerols, Glycerolipids are none other than the popular term ‘triglycerides’. They possess the bulk storage of animal fat in their tissues. Thus, Glycerolipids has an important function to store energy. ‘Seminolipid’ found in mammalian sperms is the best example here. 

The Unique Features and Applications of Lipids

Generally speaking, a vast majority of the macromolecules are put up under the classification of Polymers. However, Lipids are unique and they are not to be categorized as Polymers, unlike the carbohydrates. This is also a reason why Lipids are found in a diverse range of shapes and forms. 

Also, when their double bonds connect with 4 other Carbon atoms, then Lipids have unsaturated fats. On the other hand, when the same 4 Carbon bonds are interlinked with a single bond, then the lipids contain saturated fats. A few nonwaterproof materials found in daily living is made through the processing of lipids. 

Even human and animal insulation during cold weather is carried by the biological system with the support of lipids. Not only are lipids present in human beings and animal bodies,  but they are also to be found inside the deep layers of soil in the form of Oils. 

Hence, from energy storage to possessing cancer-fighting properties, further research studies on the source, formation, and structure of different lipids can be useful treatment protocols in the field of healthcare. 

MCQ on Lipids

1. Which Among the Following is not a Lipid?

  1. Oils 

  2. Proteins 

  3. Fats

  4. Waxes

ANSWER: B (Proteins)

2. Beta-oxidation of Fatty Acid is Commonly Seen in Which of the Following Options?

  1. Peroxisome, Mitochindria and ER

  2. Peroxisome and Mitochondria

  3. Only Mitochondria

  4. Only Peroxisome

ANSWER: C (Only Mitochondria)

3. Which of the Following Given is an Example for Drive Lipids:

  1. Steroids

  2. Carotenoids

  3. Terpenes

  4. All of the Above 

ANSWER: D (All of the Above)

4. Guess the ‘Specific Gravity’ of Lipids from the Below Choices:

  1. 0.8

  2. 0.7

  3. 1.2

  4. 1.3

ANSWER: A (0.8)

5. Unsaturated Lipid Fats are Usually Derived from Which Source Out of the Options Given?

  1. Plant Species

  2. Human beings 

  3. Aquatic animals 

  4. None of the Above

ANSWER: A (Plant Species)