Lecture 1: Evolution of Cells and Classification of Organisms (University of Hull)

Lecture 1 Introduction: Evolution of cells and classification of organisms Dr. Leonid Nikitenko E-mail: [email protected] 441287 Cell Structure and Function 24/09/24  Module 441287 You (n=150) Cell Structure...

Lecture 1 Introduction: Evolution of cells and classification of organisms Dr. Leonid Nikitenko E-mail: [email protected] 441287 Cell Structure and Function 24/09/24  Module 441287 You (n=150) Cell Structure RESPECT rule (#150) and Function Level 4 Teaching Team (n=6; 1 – 90%) Building blocks Cell: The ¥ quest for knowledge Why? What? How? ‘Would you tell me, please, which way I ought to go from here?’ ‘That depends a good deal on where you want to get to,’ said the Cheshire Cat. Who? ‘I don’t much care where’ – said Alice. ‘Then it doesn’t matter which way you go,’ said the Cat. ‘So long as I get somewhere,’ Alice added as an explanation. Where? ‘Oh, you’re sure to do that,’ said the Cat, ‘if you only walk long enough.’ Lewis Carroll (1865), p54 CANVAS Discussion sections E-mail: [email protected] ¥  Lecture aims To gain insight into various aspects of the evolution of cells and classification of organisms To have a brief overview of the cell structure and the role of individual organelles in the function of the cell What is Cell?  Cell: The word Basic structural, functional, and biological unit of all known organisms. Scientific journal Monastic cell, a small room, hut, or cave in which a monk or religious recluse lives A microprocessor architecture developed by Sony, Toshiba, and IBM Prison cell, a room used to hold people in prisons. Overview: Cells - The Fundamental Units of Life All organisms are made of cells The cell is the simplest collection of matter that can be alive All cells are related by their descent from earlier cells Cell structure is correlated to cellular function. Cell: The basis/foundation and diversity  Lecture 16 Multicellular organisms and various cell types 1 genome –> multiple cell types/tissues (differential gene expression >>> differential cell signalling )  Lectures 20 and 21 From cell to tissues, organs, organ systems and organism  Various lectures Various multicellular organisms and models +/+ -/-  The Three Domains of Life 1. BACTERIA (a) Domain Bacteria 2. ARCHAEA (b) Domain Archaea 2 m 2 m 3. EUKARYA (c) Domain Eukarya Kingdom Animalia 100 m Kingdom Plantae Protists Kingdom Fungi  Hierarchical Classification Species: Genus: Family: Order: Class: Phylum: Kingdom: Bacteria Domain: Eukarya Archaea Cell Evolution: A Brief History of (Cell) Time First organisms were single celled Fossils of bacteria-like organisms at least 3 billion years old Evidence for a common ancestor Presence of common cellular structures Presence of common biochemical building blocks Same patterns of metabolism Common genetic code (with some rare variations). Example: Presence of common cellular structures 15 m 5 m Cilia of Cilia of Paramecium windpipe cells 0.1 m Cross section of a cilium, as viewed with an electron microscope Comparing Prokaryotic and Eukaryotic Cells Sizes of the cells and organelles Common features of Prokaryotes and Eukaryotes Basic features of all cells: - Plasma membrane - Semifluid substance called cytosol - Chromosomes (carry genes) - Ribosomes (make proteins).  Prokaryotes Eukaryotes A typical A thin section A typical A thin section rod-shaped through the mammalian cell through the bacterium bacterium Bacillus (scheme) lymphocyte(TEM) (scheme) coagulans (TEM)  Exploring Eukaryotic Cells Animal Cells Fungal Cells 1 m Parent 10 m cell Cell wall Buds Vacuole Cell 5 m Nucleus Nucleus Nucleolus Mitochondrion Human cells from lining Yeast cells budding A single yeast cell of uterus (coloured TEM) (coloured SEM) (coloured TEM)  Cells with Chloroplasts Plant Cells Protistan Cells Flagella 1 m Cell 5 m 8 m Cell wall Nucleus Chloroplast Nucleolus Mitochondrion Vacuole Nucleus Nucleolus Chloroplast Chlamydomonas Cells from duckweed (coloured SEM) Cell wall (coloured TEM) Chlamydomonas (coloured TEM)  Specific cell types Spermatozoa These consists of an oval head and a tail  Nuclear Rough envelope endoplasmic NUCLEUS reticulum Smooth Nucleolus endoplasmic reticulum Chromatin Ribosomes Central vacuole Golgi Cell apparatus Microfilaments Intermediate CYTOSKELETON filaments Organelles Microtubules Mitochondrion Peroxisome Plasma membrane Chloroplast Cell wall Plasmodesmata Wall of adjacent cell  Lectures 7 & 8 Cell Membrane Protects the cell and its contents from surroundings/other cells Provides cellular integrity Provides selectivity barrier Provides cellular compartments Allows cell movement Allows interaction with other cells Provides fluidity/flexibility to the cell.  Vacuoles: Diverse Maintenance Compartments Central vacuole Food vacuoles are formed by phagocytosis Contractile vacuoles are found in many freshwater protists, pump excess water out of cells Central vacuoles are found in many mature plant cells, hold organic compounds and water. 5 m  Lecture 14 The Nucleus: Information Central The most conspicuous organelle Houses chromosomes and contains most of the cell’s genes Nuclear envelope – encloses the nucleus – double membrane – lipid bilayer – nuclear pores – continuous with ER  Lectures 11 and 12 The Endomembrane System Endoplasmic reticulum Golgi apparatus (Nuclear envelope) Endosomes, lysosomes, exosomes etc.  Lecture 10 Ribosomes: Protein Factories Ribosomes are particles (two subunits) made of ribosomal RNA and protein Ribosomes carry out protein synthesis – In the cytosol – On the outside of the endoplasmic reticulum or the nuclear envelope  Lecture 19 Mitochondria and chloroplasts change energy from one form to another Mitochondria are the sites of cellular respiration, a metabolic process that uses oxygen to generate ATP Chloroplasts, found in plants and algae, are the sites of photosynthesis Peroxisomes are oxidative organelles.  The Evolutionary Origins of Mitochondria and Chloroplasts Mitochondria and chloroplasts have similarities with bacteria – Enveloped by a double membrane – Contain free ribosomes and circular DNA molecules – Grow and reproduce somewhat independently in cells.  The Endosymbiont theory An early ancestor of eukaryotic cells engulfed a nonphotosynthetic prokaryotic Endosymbiont relationship with its host Merged into a single organism, a eukaryotic cell with a mitochondrion Photosynthetic prokaryote was taken up, becoming the ancestor of cells that contain chloroplasts.  Lectures 20 and 21 Extracellular components and connections between cells help coordinate cellular activities Most cells synthesize and secrete materials that are external to the plasma membrane These extracellular structures include – Cell walls of plants – The extracellular matrix (ECM) of animal cells – Intercellular junctions.  The Cell: A Living Unit Greater Than the Sum of Its Parts Cells rely on the integration of structures and organelles in order to function For example, a macrophage’s ability to destroy bacteria involves the whole cell, coordinating components such as the cytoskeleton, lysosomes, and plasma membrane.  The summary (I) Aims To gain insight into various aspects of the evolution of cells and classification of organisms To have a brief overview of the cell structure and the role of individual organelles in the function of the cell  The summary (II) Key concept 1: Cells - The Fundamental Units of Life All organisms are made of cells The cell is the simplest collection of matter that can be alive All cells are related by their descent from earlier cells Cell structure is correlated to cellular function.  The summary (III) Key concept 2: The eukaryotic cell’s genetic instructions are housed in the nucleus and carried out by ribosomes  The summary (IV) Key concept 3: The endomembrane system regulates protein traffic and performs metabolic functions (Nuclear envelope)  The summary (V) Key concept 4: Mitochondria and chloroplasts convert energy from one form to another Further Reading  Home work: How do cells move?  Amoeboid Movement Cortex (outer cytoplasm): gel with actin network 100 m Inner cytoplasm: sol with actin subunits Extending pseudopodium Cytoplasmic Streaming Chloroplast 30 m  Cilia and Flagella (a) Motion of flagella (b) Motion of cilia Direction of swimming Direction of organism’s movement Power stroke Recovery stroke Microtubules control the beating of cilia and flagella, locomotor appendages of some cells Cilia and flagella differ in their beating patterns  0.1 m Outer microtubule Plasma membrane doublet Dynein proteins Central microtubule Radial spoke Microtubules Cross-linking proteins between outer doublets (b) Cross section of Plasma motile cilium membrane Basal body 0.5 m 0.1 m (a) Longitudinal section Triplet of motile cilium (c) Cross section of basal body  Microtubule ATP doublets Dynein “walking” moves flagella & cilia Dynein protein (a) Effect of unrestrained dynein movement Cross-linking proteins ATP between outer doublets Dynein arms alternately grab, move, and release the outer microtubules Protein cross-links limit sliding Anchorage Forces exerted by dynein arms in cell cause doublets to curve, bending the (b) Effect of cross-linking proteins cilium or flagellum 1 3 2 (c) Wavelike motion Actin/myosin “walking”/motors facilitate muscle cell contractions Muscle cell 0.5 m Actin filament Myosin filament Myosin head How to study Cell Structure and Function? https://www.freepik.com/premium-vector/time-managment-concept-vector-illustration_6569817.htm  How to study Cell Structure and Function? 1 Revise on a regular basis, i.e. per lecture - at least 3-4 hours during the term (one before and 2-3 after the lecture), plus 3-4 hours for the exam. Check the contents of each lecture against the aims of the lecture and questions from MCQ (50 questions) on a regular basis. Can you answer all those questions? How to study Cell Structure and Function? Frequently Asked Questions Why? What? How? Who? Where? CANVAS Discussion sections E-mail: [email protected]  Take home message The puzzle of the Module 441287 Cell Structure and Function (and other modules) is in your own hands… and heads…  Thank you! E-mail: [email protected]