Introduction to Cytology Lecture PDF

Lecture 1 INTRODUCTION TO CYTOLOGY Sara Bah ra m Miran B.S c. , M.S c. in M edical M icrob iology P h.D./c i n M edic al I mm u nolog y 1 st Grad es Cyto logy (B iology I ) 1 1 st C ours e...

Lecture 1 INTRODUCTION TO CYTOLOGY Sara Bah ra m Miran B.S c. , M.S c. in M edical M icrob iology P h.D./c i n M edic al I mm u nolog y 1 st Grad es Cyto logy (B iology I ) 1 1 st C ours e 1 7 /1 1 /2 0 24  1. Introduction to Cell Biology 2. The Cell Theory 3. Cell Structure and Function 4. Types of Cells Learning 5. Cell Division 6. Stem Cells Outcome 7. Cell Differentiation 8. Kingdom Classification 9. Chemical Composition of Cells 10. Functionality of Life in Cells 11. Recommended Books 2 1. Introduction to Cell Biology Definition: Cell biology, or cytology, studies the structure, function, and behavior of cells, the fundamental unit of life. Significance: Basis for understanding tissues, organs, and the entire organism. Explains cellular processes like the cell cycle, division, and differentiation. Highlights the universality of DNA as the genetic blueprint. 3 2. The Cell Theory Historical Background: Robert Hooke (1600s): Observed “cells” in cork slices. Theodor Schwann & Matthias Schleiden (1839): “All living things are made of cells.” Rudolf Virchow (1855): “All cells come from pre-existing cells.” Key Tenets: 1. All organisms are composed of one or more cells. 2. Cells arise only by the division of pre-existing cells. 3. Cells are the smallest unit of life. 4 5 3. Cell Structure and Function Human Cell Components: Organelles: Specialized structures performing unique functions. oExamples: Nucleus, mitochondria, ribosomes, lysosomes. Plasma Membrane: oStructure: Phospholipid bilayer. oFunctions: Protection, transport, signaling. oTypes of Transport: Passive (diffusion, osmosis), Active (pumps, endocytosis). 6 3. Cell Structure and Function Human Cell Components: Cytoskeleton: Provides shape, support, and motility (composed of actin filaments, microtubules, etc.). Cellular Composition: oWater (85%). oOrganic Molecules: Proteins, lipids, carbohydrates, nucleic acids. oInorganic Substances: Minerals and ions. 7 8 4. Types of Cells Prokaryotic Cells: oFound in bacteria and archaea. oFeatures: No nucleus, circular DNA, smaller ribosomes, peptidoglycan cell walls. Eukaryotic Cells: oFound in plants, animals, fungi, and protists. oFeatures: Membrane-bound organelles, linear chromosomes, larger size. 9 10 11 5. Cell Division Types: oMitosis: Produces identical diploid cells for growth and repair. oMeiosis: Produces haploid gametes for reproduction. Karyotype: Human body cells have 46 chromosomes (23 pairs: 22 autosomes and 1 pair of sex chromosomes). 12 13 14 6. Stem Cells ◦ Definition: Unspecialized cells with the ability to self-renew and differentiate. ◦ Types of Stem Cells: 1. Embryonic Stem Cells: Found in early embryos, capable of forming any cell type. 2. Adult Stem Cells: Found throughout the body, including in tissues like bone marrow and skin, for repair and maintenance. 3. Induced Pluripotent Stem Cells (iPS): Created in the lab by reprogramming adult cells to behave like embryonic stem cells. 15 6. Stem Cells Stem Cell Differentiation: The process where stem cells specialize into distinct cell types with specific functions, guided by signals they receive. Key Properties of Stem Cells: 1. Self-Renewal: They can divide and maintain themselves over time. 2. Unspecialized: They can become different types of various specialized cells. 3. Signal-Dependent: Stem cells differentiate when they receive the right signals. 16 17 18 7. Cell Differentiation ◦ Definition: The process by which unspecialized cells become specialized to perform specific functions. ◦ Origin: All human cells are derived from the zygote (fertilized egg). ◦ Process: The zygote divides and differentiates into over 220 specialized cell types. ◦ Importance: Differentiation allows cells to acquire unique functions, such as muscle cells for contraction and nerve cells for signaling. 19 8. Kingdom Classification Criteria: Cell Type (Prokaryotic vs. Eukaryotic). Cell Number (Unicellular vs. Multicellular). Feeding Type (Autotrophic vs. Heterotrophic). 20 8. Kingdom Classification Examples: Eubacteria: Prokaryotic, peptidoglycan cell walls. Archaebacteria: Prokaryotic, live in extreme conditions. Protista: Eukaryotic, mostly unicellular. Fungi: Eukaryotic, multicellular, heterotrophic. 21 22 9. Chemical Composition of Cells 1. Proteins: Enzymes, structural components, transporters. 2. Lipids: Energy storage, signaling molecules, membrane components. 3. Carbohydrates: Energy sources, structural polymers. 4. Nucleic Acids: DNA (genetic material), RNA (protein synthesis). 23 10. Functionality of Life in Cells 1. Nutrition: Energy acquisition through absorption or photosynthesis. 2. Metabolism: Chemical reactions like respiration. 3. Growth: Increase in size or number of cells. 4. Response: Reacting to environmental stimuli. 5. Excretion: Removal of metabolic waste. 6. Homeostasis: Maintaining internal balance (e.g., temperature, pH). 7. Reproduction: Transfer of hereditary information. 24 11. Recommend Books 1. Cell and Molecular Biology (2nd Edition) by Nalini Chander & Suzan Viselli, 2019. 2. Human Evolutionary Genetics (2nd Edition) by Jobling, M. et al., 2014. 3. Concepts and Experiments (6th Edition) by Gerald Karp, 2014. 4. Concepts of Genetics (10th Edition) by William S. Klug et al., 2012. 5. Essential Cell Biology (3rd Edition) by Alberts et al., 2010. 6. Molecular Biology of the Cell (5th Edition) by Alberts et al., 2008. 7. Biology by Raven, Johnson, Loses, Mason, Singer (8th Edition), 2008. 8. Molecular Biology (6th Edition) by David Clark, 2005. 25 1. Any Questions or Comments? 26