LINGARAJ MAHAKUD

CSIR-UGC National Eligibility Test (NET) for Junior Research Fellowship and Lecturer-ship LIFE SCIENCES 1. Molecules and their Interaction Relevant to Biology 2. Cellular Organization 3. Fundamental Processes 4. Cell Communication and Cell Signaling 5. Developmental Biology 6. System Physiology – Plant 7. System Physiology – Animal 8. Inheritance Biology 9. Diversity of Life Forms 10. Ecological Principles 11. Evolution and Behavior 12. Applied Biology 13. Methods in Biology 1. MOLECULES AND THEIR INTERACTION RELAVENT TO BIOLOGY A. Structure of atoms, molecules and chemical bonds. B Composition, structure and function of biomolecules (carbohydrates, lipids, proteins, nucleic acids and vitamins). C. Stablizing interactions (Van der Waals, electrostatic, hydrogen bonding, hydrophobic interaction, etc.). D Principles of biophysical chemistry (pH, buffer, reaction kinetics, thermodynamics, colligative properties). E. Bioenergetics, glycolysis, oxidative phosphorylation, coupled reaction, g...

Eukaryotic Cell: Overview Eukaryotic cells are complex cells that have a defined nucleus enclosed within a membrane and various specialized organelles. These cells are found in plants, animals, fungi, and protists. Key Structures and Functions: 1. Nucleus Structure: Large, membrane-bound organelle containing the cell’s genetic material (DNA). Function: Controls the cell’s activities, including growth, metabolism, and reproduction. It is the "command center" of the cell. 2. Cell Membrane (Plasma Membrane ) Structure: A phospholipid bilayer with embedded proteins. Function: Regulates the entry and exit of substances, protecting the cell and allowing communication with the external environment. 3. Cytoplasm Structure: Jelly-like substance between the nucleus and the cell membrane. Function: Holds the organelles and provides a medium for biochemical reactions. 4. Mitochondria Structure: Double-membrane-bound organelle. Function: Generates energy (ATP) through cellular respiration...

The  cell cycle is a series of phases that a cell undergoes as it grows and divides to produce two daughter cells. It is crucial for development, tissue repair, and cellular reproduction. The cell cycle is highly regulated to ensure accurate DNA replication and division. Here’s an overview of the phases and regulatory mechanisms involved in the cell cycle: Phases of the Cell Cycle Interphase G1 Phase (Gap 1) : Cell Growth : The cell grows and synthesizes proteins, organelles, and other molecules necessary for DNA replication and cell function. Preparation for S Phase : Key processes include the synthesis of enzymes and proteins required for DNA replication. Checkpoint : The G1 checkpoint ensures that the cell is ready for DNA synthesis and that conditions are favorable. It checks for DNA damage, nutrient availability, and growth signals. S Phase (Synthesis) : DNA Replication : The entire genome is replicated, resulting in two identical sets of chromosomes. This phase ensures that ...

The signaling system in cells involves a complex network of pathways and interactions that regulate various cellular processes, including growth, differentiation, and response to external stimuli. Despite the diversity of signaling pathways, several common features are shared among them: 1. Signal Reception Receptors : Signaling begins when a signaling molecule (ligand) binds to a specific receptor on the target cell. Receptors are typically located on the cell surface (e.g., G-protein-coupled receptors (GPCRs), receptor tyrosine kinases (RTKs)) or inside the cell (e.g., steroid hormone receptors). Ligand Specificity : Receptors are specific to their ligands, ensuring that only appropriate signals are recognized and processed. 2. Signal Transduction Signal Relay : Once a receptor is activated, it relays the signal into the cell through a series of intracellular events. This often involves a cascade of proteins and small molecules that transmit the signal from the receptor to various i...

The centriole is a cylindrical organelle found in most animal cells and some lower plant cells. It plays a crucial role in organizing microtubules and facilitating cell division. The distinguishing features of centrioles are as follows: 1. Structure Shape : Centrioles are barrel-shaped or cylindrical. Microtubule Arrangement : Each centriole is composed of nine triplet microtubules arranged in a cylindrical pattern. This is often referred to as a 9 + 0 arrangement , meaning there are nine sets of triplets but no central microtubules. Length and Diameter : A typical centriole is about 0.2 micrometers in diameter and 0.4 micrometers in length . 2. Pairing and Location Exist in Pairs : Centrioles are typically found in pairs, positioned at right angles to each other. Together, they form the centrosome , which is the microtubule-organizing center of the cell. Location : Centrioles are located near the nucleus in the centrosome region of the cell, particularly during interphase. 3. Func...

The intrinsic and extrinsic apoptotic pathways are the two main signaling pathways that lead to apoptosis (programmed cell death). Although both pathways ultimately lead to cell death, they are triggered by different stimuli and involve distinct molecular mechanisms before converging on common effector molecules. Here’s a detailed differentiation: 1. Triggering Mechanism : Intrinsic Pathway (Mitochondrial Pathway) : Triggered by Internal Signals : The intrinsic pathway is activated in response to internal cellular stress . Common stressors include: DNA damage (from radiation, chemicals, or replication errors) Oxidative stress Hypoxia (low oxygen levels) Oncogene activation Growth factor deprivation Cytotoxic drugs This pathway is regulated primarily by the mitochondria and proteins from the BCL-2 family . Extrinsic Pathway (Death Receptor Pathway) : Triggered by External Signals : The extrinsic pathway is activated by extracellular death ligands binding to death receptors on the c...

 BCL-2  and MCL-1 inhibitors are targeted therapies used in cancer treatment because they directly influence the process of apoptosis (programmed cell death), a critical mechanism that many cancer cells evade to survive and proliferate. These inhibitors target specific proteins within the BCL-2 family, which regulate the intrinsic pathway of apoptosis. Here's how these inhibitors contribute to cancer treatment: Understanding the Role of BCL-2 and MCL-1 in Apoptosis BCL-2 family proteins are key regulators of apoptosis, and they are divided into two main groups: Pro-apoptotic proteins (e.g., BAX, BAK, PUMA, NOXA): These promote cell death by initiating mitochondrial outer membrane permeabilization (MOMP), leading to the release of cytochrome c and activation of the caspase cascade. Anti-apoptotic proteins (e.g., BCL-2, MCL-1, BCL-XL): These inhibit apoptosis by binding to and sequestering pro-apoptotic proteins, preventing them from triggering mitochondrial permeabilizatio...

 The  p53 tumor suppressor gene is a critical regulator of the cell cycle and plays a vital role in preventing cancer by maintaining genomic stability. Often called the "guardian of the genome," p53 responds to cellular stress, particularly DNA damage, and prevents the propagation of cells with genomic abnormalities. Here's how p53 regulates the cell cycle: 1. Activation of p53 Cellular Stress Signals : p53 is activated in response to a variety of stress signals, including: DNA damage (from radiation, chemicals, or replication errors) Oncogene activation (genes that have the potential to cause cancer) Hypoxia (low oxygen levels) Nutrient deprivation Oxidative stress Under normal conditions, p53 is kept at low levels by the action of MDM2 (mouse double minute 2 homolog), a protein that ubiquitinates p53, marking it for degradation. Upon DNA damage or stress, p53 is stabilized and accumulates in the cell. 2. Induction of Cell Cycle Arrest p53 exerts its effects primaril...

Facilitated diffusion is a passive transport mechanism in which molecules move across a biological membrane through specific carrier or channel proteins. Unlike simple diffusion, which involves the direct movement of molecules across the lipid bilayer, facilitated diffusion requires the assistance of these proteins to help certain substances cross the membrane. Importantly, this process does not require energy input, as it relies on the concentration gradient—substances move from areas of higher concentration to areas of lower concentration. Key Features of Facilitated Diffusion: Passive Process : Facilitated diffusion does not use cellular energy (ATP). Instead, it depends on the inherent kinetic energy of molecules and their concentration gradients. Molecules move down their gradient, from high concentration to low concentration. Selective Transport : This process is highly selective. Only specific molecules or ions are allowed to cross the membrane, depending on the structure and b...