Cell Signalling Part 1 | Signalling Molecules & Receptors | CSIR NET, GATE, CUET PG #zoology

Cell Signalling Part 1: Signalling Molecules & Receptors explained simply for CSIR NET Life Science, GATE, CUET PG, BRET and M.Sc. Zoology. 🧬 Welcome to Chunky Biology, where the life science syllabus is broken into bite-sized chunks so you can learn faster and remember longer! 📌 WHAT YOU WILL LEARN IN THIS VIDEO ✅ What is cell signalling and why cells communicate ✅ Steps of signal transduction: signal, receptor, transduction, response ✅ Types of signalling molecules (ligands) ✅ Polar (hydrophilic) signalling molecules and why they need cell surface receptors ✅ Non-polar (hydrophobic, lipophilic) signalling molecules and why they cross the plasma membrane ✅ Cell surface receptors: location, structure and function ✅ Intracellular receptors (cytoplasmic and nuclear) and their role in gene expression ✅ Examples of signalling molecules: hormones, neurotransmitters, growth factors, cytokines, steroids, nitric oxide ✅ Exam-oriented key points and common traps 🔬 POLAR VS NON-POLAR SIGNALLING MOLECULES Polar signalling molecules are water-soluble and cannot cross the lipid bilayer. They bind receptors on the cell surface and trigger a response inside the cell. Examples: peptide and protein hormones (insulin, glucagon), epinephrine, acetylcholine, growth factors (EGF), and cytokines (interleukins, interferons). Non-polar signalling molecules are lipid-soluble and diffuse directly through the plasma membrane to bind intracellular receptors. Examples: steroid hormones (cortisol, estrogen, testosterone, progesterone), thyroid hormones (T3, T4), retinoic acid, vitamin D, and nitric oxide (NO). 🔬 CELL SURFACE RECEPTORS VS INTRACELLULAR RECEPTORS Cell surface receptors are transmembrane proteins that bind hydrophilic ligands outside the cell. Major classes are ion channel-linked receptors, G-protein coupled receptors and enzyme-linked receptors. They convert an extracellular signal into an intracellular response. Intracellular receptors sit in the cytoplasm or nucleus. After ligand binding, they act as transcription factors, bind hormone response elements on DNA and alter gene expression. This is why responses to non-polar hormones are usually slower but longer-lasting. 🎯 WHO IS THIS VIDEO FOR? CSIR NET Life Science aspirants: Unit 4, Cell Communication and Cell Signaling CUET PG Life Science, Zoology and Biotechnology students M.Sc. Zoology, Biotechnology, Biochemistry and Life Science students BRET (Biotechnology Research Eligibility Test) aspirants GATE Life Sciences (XL) and GATE Biotechnology (BT) students DBT BET and GAT-B aspirants B.Sc. students building a foundation in cell biology 💡 EXAM TIPS Polar ligand = cell surface receptor. Non-polar ligand = intracellular receptor. Nitric oxide is a small gas that diffuses freely, a classic exception worth remembering. Match-the-following questions on ligands and receptor types are common, so revise the examples. Compare by speed of response, receptor location and mechanism of action. These are favourite comparison points in NET and GATE. 📚 CELL SIGNALLING SERIES This is Part 1. Watch the full playlist in order for complete cell communication coverage for CSIR NET Life Science, GATE and CUET PG. 📖 MORE FROM CHUNKY BIOLOGY CSIR NET Life Science unit-wise concept videos M.Sc. Zoology topics explained simply Previous year question (PYQ) walkthroughs Exam strategy, tips and revision notes