CSS Syllabus Paper General Science & Ability (Part-I)

BIOLOGICAL SCIENCE …

Biomolecules

Biomolecules are the building blocks of life, essential for the structure, function, and regulation of living organisms. These intricate molecules, composed primarily of carbon, hydrogen, oxygen, and nitrogen atoms, are the foundation of all biological processes. Biomolecules encompass a wide range of compounds, including carbohydrates, lipids, proteins, and nucleic acids, each playing unique roles in the intricate machinery of life. Through their diverse structures and interactions, biomolecules enable the transmission of genetic information, the storage and utilization of energy, the maintenance of cellular integrity, and the execution of countless biochemical reactions. Understanding the properties and functions of biomolecules is crucial for comprehending the complexities of life and holds immense potential for advancements in medicine, agriculture, and biotechnology.

Importance of Biomolecules

Biomolecules play a crucial role in various aspects of life and have significant importance in multiple fields. Here are five key points highlighting the significance of biomolecules:

1.    Structural and functional integrity: Biomolecules provide the structural framework for cells and tissues, ensuring their stability and integrity. For example, proteins form the structural components of cells and tissues, while lipids create cell membranes. Additionally, biomolecules such as collagen provide structural support to bones, tendons, and connective tissues.

2.    Energy storage and utilization: Biomolecules, particularly carbohydrates and lipids, serve as essential energy sources for organisms. Carbohydrates, such as glucose, are broken down through metabolic processes to release energy required for cellular activities. Lipids, in the form of triglycerides, serve as long-term energy reservoirs in the body, providing a concentrated source of energy.

3.    Information storage and transmission: Nucleic acids, specifically DNA and RNA, are biomolecules responsible for storing and transmitting genetic information. DNA carries the hereditary information, while RNA acts as a messenger molecule, transferring genetic instructions from DNA to the cellular machinery for protein synthesis. Understanding biomolecular mechanisms is crucial for advancements in genetics and gene-based therapies.

4.    Enzymatic reactions and catalysis: Proteins, including enzymes, are biomolecules that act as catalysts in biochemical reactions. Enzymes facilitate the conversion of substrates into products by lowering the activation energy required for the reaction to occur. Enzymatic reactions are vital for metabolism, digestion, DNA replication, and numerous other physiological processes.

5.    Biotechnological applications: Biomolecules have immense significance in biotechnology and biomedical research. They are utilized in various applications, including the production of recombinant proteins, development of diagnostic tests, drug discovery, and genetic engineering. Biomolecules are also key targets for drug design, as many diseases result from dysregulation or malfunction of specific biomolecules.

Overall, biomolecules are fundamental to life, influencing structure, function, energy metabolism, genetic information, and the development of innovative technologies. The study and manipulation of biomolecules have far-reaching implications, shaping our understanding of biology and driving advancements in fields such as medicine, agriculture, and biotechnology.

Types of Biomolecule

Following are the major types of biomolecules:

1.    Carbohydrates

2.    Lipids

3.    Proteins

4.    Nucleic acids (DNA and RNA)

1.   Proteins

Proteins are versatile biomolecules that serve as the workhorses of life, performing a multitude of essential functions in living organisms. Composed of long chains of amino acids, proteins are involved in almost every aspect of cellular structure and function.



From providing structural support to catalyzing chemical reactions, proteins are involved in processes ranging from muscle contraction and immune response to hormone regulation and enzyme activity. These remarkable molecules exhibit a diverse array of structures, shapes, and functions, allowing them to carry out specific roles within cells and tissues. Understanding the intricate nature of proteins is crucial for unraveling the complexities of life and holds great promise for advancements in medicine, biotechnology, and our overall understanding of biological systems.

Bonding in protein

Proteins exhibit several types of bonding that contribute to their three-dimensional structure and functionality. The primary type of bonding involved in protein structure is covalent bonding, which occurs between the amino acids within the protein chain. Covalent bonds form through the sharing of electrons, creating a strong and stable linkage. Disulfide bonds, a specific type of covalent bond, are formed between two cysteine amino acids and contribute to the overall stability of protein structure. In addition to covalent bonding, proteins also rely on non-covalent interactions, such as hydrogen bonds, ionic bonds, and van der Waals forces. These interactions are weaker than covalent bonds but play a crucial role in determining the protein's shape, stability, and interactions with other molecules. Hydrogen bonds form between hydrogen and electronegative atoms, while ionic bonds arise from the attraction between oppositely charged ions. Van der Waals forces are weak attractions between atoms or molecules due to temporary fluctuations in electron distribution. The combined effects of these various bonding interactions give proteins their unique structures and enable them to carry out their diverse biological functions.

Functions of Proteins

  • Enzymatic activity: Proteins function as enzymes, catalyzing chemical reactions in the body, facilitating various metabolic processes, and promoting the conversion of substrates into products.
  • Structural support: Proteins provide structural integrity to cells, tissues, and organs. They form the framework for muscles, bones, tendons, and skin, ensuring the stability and strength of these structures.
  • Transport and signaling: Some proteins act as carriers, transporting molecules and ions across cell membranes or throughout the body. Additionally, proteins serve as signaling molecules, relaying messages between cells and coordinating physiological responses.
  • Immune defense:  Antibodies, a type of protein, play a crucial role in the immune system, identifying and neutralizing harmful foreign substances such as bacteria, viruses, and toxins.
  • Regulation and control: Proteins are involved in regulating various biological processes, including gene expression, cell cycle progression, and signal transduction pathways. They control the timing and magnitude of cellular activities, ensuring proper functioning and maintaining homeostasis.
  • Muscle contraction: Proteins, specifically actin and myosin, are responsible for the contraction and relaxation of muscles. The interaction between these proteins enables movement and locomotion in animals.
  • Molecular recognition and binding: Proteins can bind to specific molecules, such as hormones, neurotransmitters, and nutrients, enabling cellular uptake, signal transduction, and regulatory functions.

It's important to note that proteins have a wide range of functions, and the list provided above is not exhaustive but highlights some of the major roles they play in biological systems.

2.  Carbohydrates

Carbohydrates, often referred to as saccharides or sugars, are essential biomolecules found in all living organisms. These versatile compounds serve as a primary source of energy and play crucial roles in various biological processes. Composed of carbon, hydrogen, and oxygen atoms in specific ratios, carbohydrates come in various forms, including simple sugars (monosaccharides), double sugars (disaccharides), and complex carbohydrates (polysaccharides). 

Carbohydrates are not only a vital fuel source for cellular respiration, but they also contribute to cell structure, cell-cell communication, and serve as recognition molecules. Additionally, certain carbohydrates, such as cellulose and chitin, provide structural support in plant cell walls and the exoskeletons of arthropods, respectively. Understanding the functions and properties of carbohydrates is essential for comprehending metabolism, nutrition, and the intricate workings of living systems. Moreover, carbohydrates hold significant importance in areas such as food science, biofuel production, and medicinal research.

Bonding in Carbohydrates

Carbohydrates primarily exhibit two types of bonding: covalent bonding and hydrogen bonding. Covalent bonding occurs between the carbon and oxygen or carbon and hydrogen atoms within the carbohydrate molecule. These strong covalent bonds create the backbone of the carbohydrate structure. Hydrogen bonding, on the other hand, involves the weak attraction between the oxygen and hydrogen atoms in different carbohydrate molecules. Hydrogen bonding contributes to the formation of larger carbohydrate structures, such as polysaccharides, and influences their physical properties. These bonding interactions are critical for maintaining the stability and structure of carbohydrates, as well as their interactions with other biomolecules.

Functions of Carbohydrates

  • Energy source: Carbohydrates are a primary source of energy in living organisms. They are broken down during cellular respiration to produce ATP, the main energy currency of cells.
  • Energy storage: Carbohydrates serve as a storage form of energy. Plants store glucose as starch, while animals store it as glycogen in the liver and muscles for later use.
  • Structural support: Certain carbohydrates, such as cellulose in plants and chitin in arthropods, provide structural support to cells and tissues. They form the cell walls of plants and the exoskeletons of insects and crustaceans.
  • Cellular communication: Carbohydrates play a role in cell-cell communication and recognition processes. They are present on the surface of cells as glycoproteins or glycolipids, participating in cell signaling, immune responses, and cell adhesion.
  • DNA and RNA synthesis: Carbohydrates, specifically deoxyribose and ribose sugars, are integral components of DNA and RNA, respectively. These sugars form the backbone of nucleic acids, which carry genetic information and participate in protein synthesis.
  • Metabolic intermediates: Some carbohydrates, such as glucose, serve as intermediates in metabolic pathways. They can be converted into other molecules, such as amino acids, fatty acids, and nucleotides, which are crucial for various cellular processes.
  • Dietary fiber and digestion: Carbohydrates, particularly dietary fiber, play a role in maintaining digestive health. Fiber adds bulk to the diet, aids in digestion, promotes regular bowel movements, and helps prevent conditions like constipation and diverticulosis.

These functions highlight the diverse roles that carbohydrates play in energy metabolism, structural support, cell communication, and overall physiological processes in organisms.

3.  Lipids

Lipids are a diverse group of biomolecules that are crucial for life and play a multitude of essential roles in living organisms. Composed primarily of carbon, hydrogen, and oxygen atoms, lipids are characterized by their hydrophobic nature, making them insoluble in water. They encompass a wide range of compounds, including fats, oils, phospholipids, steroids, and waxes. Lipids serve as a concentrated source of energy, providing more than twice the amount of energy per gram compared to carbohydrates or proteins. Moreover, lipids form the structural components of cell membranes, ensuring their integrity and selective permeability. Lipids also act as signaling molecules, participate in insulation and protection, and play vital roles in hormone production, vitamin absorption, and nerve transmission. Understanding the diverse functions and properties of lipids is crucial for comprehending the complexities of cellular processes, metabolism, and maintaining overall health. Additionally, lipids have significant implications in areas such as nutrition, biochemistry, and the development of therapeutic interventions.

Bonding in Lipids

Lipids exhibit various types of bonding, including nonpolar covalent bonds and weak intermolecular forces. The primary bonding within lipids is nonpolar covalent bonding, which occurs between carbon and hydrogen atoms in hydrocarbon chains. These covalent bonds contribute to the hydrophobic nature of lipids. Additionally, lipids can have ester linkages, which form between the hydroxyl group of a fatty acid and the carboxyl group of glycerol in triglycerides and phospholipids. In terms of intermolecular forces, lipids are held together by van der Waals forces, which are weak attractive forces between adjacent lipid molecules. These bonding interactions contribute to the unique properties and functions of lipids, such as their insolubility in water and their ability to form cell membranes and store energy efficiently.

Functions of Lipids

  • Energy storage: Lipids serve as a highly efficient storage form of energy in organisms. They can be broken down to release a large amount of energy, providing fuel for metabolic processes.
  • Structural component: Lipids play a vital role in forming the structure of cell membranes. Phospholipids, the main component of cell membranes, create a lipid bilayer that regulates the passage of molecules in and out of cells.
  • Insulation and protection: Lipids, such as adipose tissue, act as an insulating layer, helping to regulate body temperature. They also provide cushioning and protection to vital organs.
  • Hormone production: Certain lipids, such as cholesterol and steroid hormones, serve as precursors for the synthesis of hormones. These hormones play essential roles in regulating various physiological processes.
  • Cell signaling: Lipids act as signaling molecules and participate in cellular communication. Lipid-derived signaling molecules, such as prostaglandins and phosphoinositides, mediate processes like inflammation, blood clotting, and cell growth.
  • Absorption of fat-soluble vitamins: Lipids aid in the absorption and transport of fat-soluble vitamins (A, D, E, and K) in the body, ensuring their availability for various physiological functions.

These functions highlight the importance of lipids in energy metabolism, structural integrity, hormonal regulation, cell communication, and overall physiological homeostasis in living organisms.

4.  Vitamins

Vitamins are essential organic compounds that are required in small quantities for the proper functioning and maintenance of the human body. They play a crucial role in various physiological processes, acting as coenzymes, antioxidants, and regulators of metabolism. Vitamins are classified into two main categories: water-soluble vitamins (such as the B vitamins and vitamin C) and fat-soluble vitamins (including vitamins A, D, E, and K). 

Water-soluble vitamins are not stored in the body and need to be consumed regularly, while fat-soluble vitamins can be stored in adipose tissue and the liver for longer periods. Each vitamin has specific functions and is involved in processes such as energy production, immune function, vision, bone health, blood clotting, and cell growth. A deficiency or excess of vitamins can lead to various health issues and diseases. Adequate intake of vitamins through a balanced diet or supplements is essential for maintaining optimal health and preventing deficiencies.

Types of Vitamins

Following are the types of vitamins:

1.    Vitamin A

2.    Vitamin B1 (Thiamine)

3.    Vitamin B2 (Riboflavin)

4.    Vitamin B3 (Niacin)

5.    Vitamin B5 (Pantothenic acid)

6.    Vitamin B6 (Pyridoxine)

7.    Vitamin B7 (Biotin)

8.    Vitamin B9 (Folate or Folic acid)

9.    Vitamin B12 (Cobalamin)

10.                Vitamin C

11.                Vitamin D

12.                Vitamin E

13.                Vitamin K

Functions of Vitamins

1.    Vitamin A: Essential for vision, immune function, and cell growth and differentiation.

2.    Vitamin B1 (Thiamine): Plays a key role in energy metabolism, nerve function, and carbohydrate metabolism.

3.    Vitamin B2 (Riboflavin): Involved in energy production, antioxidant activity, and the metabolism of fats, carbohydrates, and proteins.

4.    Vitamin B3 (Niacin): Required for energy production, DNA repair, and the maintenance of healthy skin and nerves.

5.    Vitamin B5 (Pantothenic acid): Important for energy metabolism, hormone synthesis, and the production of red blood cells.

6.    Vitamin B6 (Pyridoxine): Supports brain development, the production of neurotransmitters, and the metabolism of proteins, carbohydrates, and fats.

7.    Vitamin B7 (Biotin): Essential for the metabolism of carbohydrates, fats, and amino acids, as well as for healthy hair, skin, and nails.

8.    Vitamin B9 (Folate or Folic acid): Crucial for DNA synthesis and cell division, as well as for preventing certain birth defects.

9.    Vitamin B12 (Cobalamin): Required for the production of red blood cells, nerve function, and DNA synthesis.

10.                Vitamin C: Acts as an antioxidant, supports immune function, and aids in collagen synthesis for healthy skin, bones, and connective tissues.

11.                Vitamin D: Promotes calcium absorption and bone health, plays a role in immune function, and may have other potential health benefits.

12.                Vitamin E: Functions as an antioxidant, protects cells from oxidative damage, and supports immune function and healthy skin.

13.                Vitamin K: Essential for blood clotting, bone metabolism, and may have a role in regulating blood calcium levels.

Enzymes

Enzymes are remarkable biological molecules that serve as catalysts for chemical reactions in living organisms. These protein-based catalysts play a fundamental role in speeding up chemical reactions by lowering the activation energy required for the reaction to occur. Enzymes are highly specific, each designed to catalyze a particular reaction or group of reactions. They facilitate a wide range of biochemical processes, including metabolism, digestion, DNA replication, and cellular signaling. Enzymes achieve their catalytic efficiency through their unique three-dimensional structures, which provide active sites where specific substrates bind and undergo chemical transformations. The regulation of enzymes is crucial for maintaining optimal cellular function, and factors such as temperature, pH, and the presence of inhibitors or activators can influence their activity. The study of enzymes has significant implications in medicine, biotechnology, and drug development, as understanding their mechanisms and functions offers insights into various diseases and the design of therapeutic interventions.

Types of Enzyme

1.    Oxidoreductases

2.    Transferases

3.    Hydrolases

4.    Lyases

5.    Isomerases

6.    Ligases

Function of Enzymes

1.    Amylase: Breaks down starch and carbohydrates into smaller sugars, aiding in digestion.

2.    Lipase: Catalyzes the breakdown of fats (lipids) into fatty acids and glycerol, facilitating digestion and absorption of dietary fats.

3.    Protease: Assists in the breakdown of proteins into amino acids, aiding in digestion and protein metabolism.

4.    DNA polymerase: Participates in DNA replication, synthesizing new strands of DNA during cell division and DNA repair.

5.    RNA polymerase: Catalyzes the synthesis of RNA from DNA templates, enabling gene expression and protein synthesis.

6.    ATP synthase: Generates ATP (adenosine triphosphate), the primary energy currency of cells, by utilizing a proton gradient across cellular membranes.

7.    Catalase: Converts hydrogen peroxide, a toxic byproduct of metabolism, into water and oxygen, protecting cells from oxidative damage.

8.    Carbonic anhydrase: Facilitates the interconversion of carbon dioxide and bicarbonate ions, playing a crucial role in maintaining acid-base balance and gas exchange in the body.

9.    Reverse transcriptase: Converts RNA into DNA, a critical step in retroviral replication and the production of complementary DNA (cDNA) for molecular biology techniques.

10.                Polymerase chain reaction (PCR) enzymes: Include Taq polymerase and DNA polymerases with heat-resistant properties, enabling the amplification of DNA sequences in molecular biology and diagnostics.

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