Biological Molecules – Types, Structure, Functions & Examples Explained

Biological Molecules are organic compounds found in living organisms that are tightly bound by covalent bonds, such as water-insoluble lipids and hydrogen-bonded proteins.

Macromolecules are large biological structures that are made up of smaller monomer units to form polymers. There are four basic types: carbohydrates, lipids, proteins, and nucleic acids. All of them play key roles in biological processes, such as energy supply, cell structure, and the transmission of genetic information.

Start Your Test Now


Biological Molecules

Note

This is just a sample test paper for the AFNS Initial Test! If you want to pass the LCC Initial Test with a 100% guarantee, get our Premium Notes now for only 200 rupees.

✅ Trusted by thousands of successful candidates
✅ Easy and effective study material
✅ Best notes to help you pass

Don't waste time! BUY NOW and secure your success!

1 / 49

A peptide bond is formed between the carboxyl group of one amino acid and the amino group of another through a process called:

2 / 49

Enzymes are biological catalysts that are mainly:

3 / 49

A high content of triglycerides are found in:

4 / 49

The bond formed between two monosaccharides is called a:

5 / 49

A molecule with a phosphate group, a five-carbon sugar, and a nitrogenous base is called a:

6 / 49

The primary source of energy for most living organisms is:

7 / 49

Hemoglobin has:

8 / 49

Mineral associated with cytochrome is:

9 / 49

A triglyceride is a:

10 / 49

Which class of molecule is the major component of cell membrane?

11 / 49

Lipids are a diverse group of biological molecules that are primarily:

12 / 49

The bond that connects a fatty acid to glycerol is a(n):

13 / 49

The most common secondary structure of proteins is:

14 / 49

Which of the following is an example of a saturated fatty acid?

15 / 49

Name the simplest amino acid.

16 / 49

Which is a reducing sugar?

17 / 49

Which of the following is a component of a nucleotide?

18 / 49

All of the following are organic compounds except:

19 / 49

The secondary structure of a protein is primarily stabilized by:

20 / 49

DNA and RNA are examples of:

21 / 49

Most abundant RNA in the cell is:

22 / 49

Koshland's theory of enzyme action is known as:

23 / 49

Which of the following is a phospholipid?

24 / 49

The molecule that serves as the genetic material in most organisms is:

25 / 49

The storage form of carbohydrates in animals is:

26 / 49

The building blocks of proteins are:

27 / 49

Which is the most abundant biomolecule on earth?

28 / 49

β-oxidation occurs in:

29 / 49

The sugar found in RNA is:

30 / 49

Which of the following is an example of a monosaccharide?

31 / 49

Glycogen is an example of:

32 / 49

Which is an organic molecule?

33 / 49

Steroids are classified as:

34 / 49

The fastest enzyme is:

35 / 49

In which of the following an anticodon occurs?

36 / 49

The plant storage form of carbohydrate is:

37 / 49

The process by which a protein loses its three-dimensional structure and becomes non-functional is called:

38 / 49

In RNA, the Nitrogen base that takes the place of thymine is:

39 / 49

The monomer of a carbohydrate is:

40 / 49

Which of the following is a structural polysaccharide found in the cell walls of plants?

41 / 49

Which one is a protein?

42 / 49

The primary function of triglycerides is:

43 / 49

Which of these lipids is a major component of cell membranes?

44 / 49

When a protein undergoes a hydrolysis reaction, the end-products are:

45 / 49

The type of bond that links nucleotides together to form a nucleic acid strand is a:

46 / 49

The term enzyme was coined by:

47 / 49

Which of the following is a disaccharide?

48 / 49

Which of the following nitrogenous bases is found only in DNA?

49 / 49

Which of the following is not a function of lipids?

Your score is

The average score is 47%

0%

Importance of Macromolecules

The importance of macromolecules in all living organisms is fundamental because it is these polymers made up of monomers that are responsible for the structure and function of cells. For example, carbohydrates are the primary energy stores, and proteins function as cell building blocks, enzymes, and hormones.

Furthermore, lipids provide structure and protection through the phospholipid bilayer of cell membranes, while nucleic acids, namely DNA and RNA, are the stores of genetic information, which are made up of nucleotides. All of these molecules play a key role in the complex processes of life, such as heredity, development, and energy conversion.

In the biological field, chemical bonds, such as covalent bonds and hydrogen bonds, that are part of the structure of macromolecules ensure their stability and specific functions. It is through these bonds that proteins remain in their interactions and defined order, and the double helix structure of DNA is stabilized.

Without these bonds, internal processes such as enzyme reactions, cell transport, and genetic renewal would not be possible. These molecules are the foundation of living systems, generating energy, building cells, and passing genetic traits from one generation to the next.

4 Biological Macromolecules

  • Carbohydrates
  • Proteins
  • Lipids
  • Nucleic Acids (DNA and RNA structure and function).

4 Biological molecules

Carbohydrates Definition

Carbohydrates are organic compounds that are the main source of energy. They consist of starch and sugar and provide immediate energy to the body. Carbohydrates are formed during photosynthesis in plants, and humans obtain them through food. These compounds are broken down in the body to produce energy and can also be stored in excess. They are essential for the growth of the human body and mental performance.

Examples of Carbohydrates

Here are the main types and examples of carbohydrates, which are the main source of energy for the human body. Glucose and fructose are common simple sugars found in fruits and honey. Sucrose is the sugar that is included in everyday sugar. Starch, which is abundant in potatoes and rice, is a complex carbohydrate. Similarly, fibrous components such as cellulose, which is found in vegetables and grains, are very useful for digestion. All these examples show that carbohydrates are an essential part of the diet.

Importance of Carbohydrates 

Carbohydrates are the main source of energy for the human body, which is essential for daily physical activities and mental function. They are obtained through food and are converted into glucose in the body, providing instant energy. They help improve the digestive system and maintain balanced blood sugar levels. In addition, fibrous carbohydrates help prevent problems like constipation and also play an important role in weight control. Therefore, the right amount of carbohydrates in a balanced diet is of utmost importance.

What are Carbohydrate Foods?

Carbohydrate foods are foods that contain starch, sugar, fiber, energy, glucose, fiber, dietary fiber, and natural sweeteners. These components provide instant energy to the body and control blood sugar levels. Rice, wheat, corn, potatoes, pulses, fruits, vegetables, and milk are prominent examples of such foods. Since these foods help keep the body active and meet daily needs, any such food is called a carbohydrate food.

Types of Carbohydrates

Monosaccharides Carbohydrates

Monosaccharides are carbohydrates, the simplest type of sugar, containing a single sugar unit and providing immediate energy. Examples include glucose, fructose, and galactose, which are found in fruits, honey, and milk.

Disaccharides Carbohydrates 

Disaccharides are carbohydrates made up of two sugar units that are joined together to provide energy. Examples include sucrose (a common sugar), lactose (the sugar found in milk), and maltose (found in barley).

Polysaccharides Carbohydrates 

All large sugar compounds that are made up of many sugar units, such as starch, cellulose, glycogen, etc., are called polysaccharide carbohydrates.

Functions of Carbohydrates

  • Providing energy: Carbohydrates provide the body with instant energy that is essential for daily activities.
  • Maintaining blood sugar balance: They maintain a balanced blood glucose level, which is important for physical and mental health.
  • Improving mental performance: The brain gets a large portion of its energy from carbohydrates, which helps in enhancing memory and focus.
  • Improving the digestive system: Fibrous carbohydrates improve digestion and prevent constipation.
  • Energy storage: Excess carbohydrates are stored in the body in the form of glycogen in the liver and muscles.
  • Role in body structure: Some carbohydrates, such as cellulose, provide cell wall structure, which is important for plants.

Monomers of Carbohydrates 

The basic unit of carbohydrates is called a monomer, which is usually glucose. It is a simple sugar called a monosaccharide and serves as the basic building block for making other larger sugar compounds. Sugar units such as glucose, fructose, and galactose are linked in various ways to form disaccharides and polysaccharides, which meet the major human energy needs.

monomers of carbohydrates

Macromolecules of Carbohydrates

Carbohydrate macromolecules are large organic compounds that provide biochemical energy. They include important components such as polysaccharides, which are made up of many units of monosaccharides such as glucose. Starch, cellulose, and glycogen are well-known polymers that help store energy and build cellular structures. These compounds are found in natural foods and play a crucial role in the growth, movement, and cellular processes of living organisms.

Low-carb Diet

A low-carb diet is a dietary plan that aims to improve health by reducing the intake of starchy foods such as sugar, flour, and rice. This diet is especially beneficial for people who want to lose weight or control diabetes. It includes low-carb vegetables, low-starch foods, and low-carb foods such as low-carb breakfasts, low-starch cereals, low-carb chips, low-starch snacks, and sometimes even low-carb bread. Although this diet may benefit some people, it is important to consult a dietitian or doctor before adopting it to avoid negative health effects.

What are lipids

Lipids are organic carbon compounds that are insoluble in water but soluble in organic solvents. They are formed by esterification of hydrocarbon chains of fatty acids with glycerol or other alcohols. Due to their hydrophobic properties, they play an important role in cell membranes, where some lipids have an amphipathic structure—that is, one end is water-loving and the other is water-fearing. As a source of stored energy, triglycerides are stored in adipose tissue, while phospholipids and steroids (such as cholesterol) contribute to biological signaling and cell structure.

Examples of lipids

Lipids are not only an essential part of food, but the body itself also produces them through specific chemical processes. They also help maintain body temperature and protect internal organs. Ghee, butter, olive oil, coconut oil, beeswax, fish oil, cholesterol, phospholipids, triglycerides, and steroids are all examples of lipids.

Monomers of lipids

Lipid monomers are the basic units that combine to form larger fat molecules, and they are composed of fatty acids and glycerol. The basic sources of lipids are fatty acids and glycerol, which combine to form a variety of fatty compounds.

For example, triglycerides are formed by linking three fatty acids to glycerol through ester bonds. This process is called dehydration synthesis, in which water is removed. Similarly, phospholipids are formed by adding a phosphate group to two fatty acids and one glycerol, and because they have one end toward water and the other away from water.

These molecules have amphipathic properties, which help to establish order in cell membranes. Although lipids are not traditional polymers, they are made up of the same basic monomers and play important roles in energy, structure, and signaling systems.

Biological Lipids

Biological lipids are biological compounds that are insoluble in water, are generally hydrophobic, and play key roles in energy storage, structural protection, and signaling. The main types include triglycerides (which store energy), phospholipids, and sterols such as cholesterol, which maintain the structure and fluidity of cell membranes.

The amphipathic nature of phospholipids makes them ideal for the hydrophilic heads to face the water and the hydrophobic parts to face the inside. This arrangement helps form the lipid bilayer in cell membranes. Lipids not only store energy, but also function as signaling molecules, especially those lipids that are converted into prostaglandins or other bioactive derivatives.

Furthermore, cholesterol and fats are transported in the blood by lipoproteins, with HDL considered “good” and LDL “bad” for health reasons. All of these roles are key to body balance, cellular protection, and energy systems.

Macromolecule of Lipids

Biological lipids are large, water-insoluble compounds that play important roles in cell membrane structure, energy storage, and cellular signaling. Triglycerides provide energy storage, phospholipids form the basis of the lipid bilayer, and sterols such as cholesterol help strengthen membranes and synthesize hormones. All of these compounds play a key role in overall physiological balance and biological safety.

Cell Membrane Phospholipid

The basic structure of the cell membrane is composed of naturally amphipathic phospholipids; that is, a hydrophilic head interacts with water while two hydrophobic tails repel water. They spontaneously form a two-layer structure in water, called a lipid bilayer, with the heads facing outward and the tails facing inward, separating the cell’s interior and exterior.

This bilayer results in selective permeability; some small hydrophobic molecules can pass through easily, while larger polar or charged molecules require transport proteins. Under the fluid mosaic model of cellular processes, this membrane remains flexible, and the proteins and lipids within the membrane can move freely, which plays an important role in cell signaling, movement, and cell identification.

cell membrane phospholipid

Medium Chain Triglyceride Oil

Medium Chain Triglyceride Oil is a type of oil that is made up of medium-chain fatty acids, usually obtained from coconut oil extraction or palm oil. The special thing about this oil is that it is easily converted into energy through rapid metabolism and produces ketones, which increase mental and physical energy.

Its digestibility is easier than long-chain fats (LCTs), which makes it more suitable for people with malabsorption disorders. Furthermore, it can help with weight management because it provides immediate energy but is less likely to be stored as body fat. However, since it is also a saturated fat, it is important to consume it in moderation.

Medium chain triglyceride oil

Proteins

Proteins are large macromolecules made up of long, specifically arranged chains of amino acids (called polypeptide chains), linked together by peptide bonds. Each protein performs a specific function based on its unique structure and shape, such as being enzymes that catalyze chemical reactions, an antibody for the immune system, a transport protein that transports materials around the body, a building physical structure as a structural protein, or sending signals in the form of hormones. These proteins play a fundamental role in cellular regulation and bodily functions in various cellular systems.

Example of Protein

Some well-known examples of proteins include hemoglobin, which carries oxygen in the blood, collagen, which gives strength and flexibility to body structures, and insulin, which balances blood sugar levels. Furthermore, some proteins, such as amylase and pepsin, act as enzymes to digest food, while antibodies protect the body from disease. In addition, transport proteins and motor proteins, such as hemoglobin, albumin, actin, and myosin, play a fundamental role in the movement of substances and bodily movements.

Importance of Proteins

Proteins are one of the body’s essential macronutrients, playing a central role in growth and repair processes, enzymes that speed up chemical reactions, and immune system components such as antibodies that help in the body’s defenses. They maintain fluid balance, signal in the form of hormones, and transport oxygen and nutrients to cells through transport proteins.
They provide structural support, regulate metabolism, and increase satiety by reducing hunger, which makes it easier to control weight. Protein is found in all cells and is essential for the basic activities of life.

Types of proteins

There are many types of proteins that perform different functions in the body. Structural proteins, such as collagen and keratin, provide structural support. Enzymes help convert food into energy. Transport proteins, such as hemoglobin, carry oxygen to cells, while hormonal proteins, such as insulin, regulate bodily functions.
Defense proteins, such as antibodies, protect the body from disease; contractile proteins, such as actin and myosin, move muscles, and storage proteins store nutrients or iron. In addition, proteins are classified based on their fibrous and globular structure, and some membrane proteins form part of the cell membrane to facilitate signaling and the movement of molecules.
  • Structural proteins: provide structure and strength to the body.
    Examples: collagen, keratin
  • Enzyme proteins: These proteins speed up chemical reactions.
    Examples: amylase, pepsin
  • Transport proteins: These proteins transport materials in the body.
    Examples: hemoglobin, albumin
  • Harmful proteins: These proteins regulate body functions.
    Examples: insulin, growth hormone
  • Immune proteins: These proteins protect the body from disease.
    Examples: antibodies, complement proteins
  • Contractile proteins: These proteins help in muscle movement.
    Examples: actin, myosin
  • Storage proteins: These proteins store energy or minerals.
    Examples: ferritin, ovalbumin
  • Fibrous proteins: These proteins are long, strong, and flexible.
    Examples: Elastin, Keratin
  • Globular Proteins: These proteins are spherical and are soluble in water.
    Examples: Enzymes, Antibodies
  • Membrane Proteins: These proteins reside in the cell membrane and transmit signals or materials.
    Examples: Channel Proteins, Receptor Proteins

What are Nucleic Acids

Nucleic acids are large biological biomolecules that are responsible for storing, transmitting, and expressing genetic information in living cells. They consist of polynucleotide chains, i.e., long chains made up of nucleotides, which are made up of three parts: a nitrogenous base, a five-carbon sugar (deoxyribose in DNA and ribose in RNA), and a phosphate group.
The two main types are DNA (the blueprint for family inheritance) and RNA (which helps make proteins). DNA transfers information and directs protein synthesis in living cells, while RNA participates in gene transcription, expression, and organization through its various forms (mRNA, tRNA, rRNA, etc).

EX Of Nucleic Acids

Deoxyribonucleic acid (DNA), ribonucleic acid (RNA), messenger RNA (mRNA), transfer RNA (tRNA), and ribosomal RNA (rRNA)—all are examples of nucleic acids.

What is DNA 

DNA is a highly complex hereditary material that is part of the genome in our cells. It stores information in the form of nucleotides, where four types of base pairs are linked together to form a double helix-like structure. Each gene gives instructions for making specific characteristics or proteins in the body based on this genetic code. Through DNA replication, complete information is transmitted to each dividing cell, and this information is organized in the form of chromosomes.

DNA structure

What is RNA

RNA is a linear molecule made up of building blocks called ribonucleotides, which include a sugar called ribose, a phosphate group, and a nitrogenous base such as uracil, linked by a phosphodiester bond. It is produced from DNA by the process of transcription within the cell and is divided into different types, such as mRNA, tRNA, and rRNA. mRNA takes the information from DNA to make proteins and translates it into the correct sequence of amino acids, while tRNA delivers specific amino acids to the correct location, and rRNA helps in the structure and function of ribosomes.

Leave a Reply