4BBY1030 Cell Biology & Neuroscience Lecture 3 PDF

FoLSM/IoPPN Dr Clemens Kiecker 4BBY1030 Cell Biology & Neuroscience Lecture 3 Neuroscience Education Cells in their environment Learning outcomes By the end of this lecture you should be able to: Speculate on the origins of cellular life forms on earth Explain the concept of cellular specialisation...

FoLSM/IoPPN Dr Clemens Kiecker 4BBY1030 Cell Biology & Neuroscience Lecture 3 Neuroscience Education Cells in their environment Learning outcomes By the end of this lecture you should be able to: Speculate on the origins of cellular life forms on earth Explain the concept of cellular specialisation in the context of multicellularity Provide an overview of cellular and subcellular pathogens Dr Clemens Kiecker Topic title: Cells in their environment Chapter 1 The origins of cellular life Dr Clemens Kiecker Topic title: Cells in their environment 3 The phylogenetic tree of cells Dr Clemens Kiecker Topic title: Cells in their environment 4 Evolution of LUCA (the last universal common ancestor of cells) HCHO, HCN, cyanamide, glyceraldehyde, PO43- etc. Minerals as catalysts, high temperatures in hydrothermal vents RNA world, ribozymes DNA more stable Lipid bilayers spontaneously form vesicles [Pollard (2017) Cell Biology] Dr Clemens Kiecker Topic title: Cells in their environment 5 Bacteria and archaea One cellular compartment, no organelles Specializations: e.g. flagella Huge variety (approx. 1 mio species known) Adapt to extreme environments (halophiles, thermophiles, acidophiles etc.) and sources of energy (hydrogen, methane, sulfate etc.) Reproduction: error-prone, but fast Our microbiome: 40,000 species, 30-50 trillion bacterial cells [New Scientist (2019)] Dr Clemens Kiecker Topic title: Cells in their environment 6 The endosymbiotic theory Mitochondria: symbiotic relationship between archaea and bacterium à endosymbiotic theory Chlorophyll-based photosynthesis Photosystem I à green sulfur bacteria and heliobacteria Photosystem II à purple and green filamentous bacteria Cyanobacteria Dr Clemens Kiecker Topic title: Cells in their environment 7 Protozoans Dr Clemens Kiecker Single-celled eukaryotes Motility, predation Not animals, plants (algae) or fungi Topic title: Cells in their environment 8 Chapter 2 Multicellularity Dr Clemens Kiecker Topic title: Cells in their environment 9 Cellular specialization Dr Clemens Kiecker Topic title: Cells in their environment 10 Ex ovo omnia Lat. ‘Everything from the egg’ William Harvey (1651) Dr Clemens Kiecker Sexual reproduction versus parthenogenesis Embryogenesis requires tight control of cell division, morphogenesis and differentiation (Lecture 18 and 4BBA1010) Topic title: Cells in their environment 11 Origins of multicellularity Volvox (Volvox carteri): colonial green alga Two cell types: somatic cells (differentiated, mortal) and germ cells (gonidia, reproductive, immortal) [Matt & Umen (2016) Dev Biol 419:99-113] Dr Clemens Kiecker Topic title: Cells in their environment 12 Origins of social behaviour Dictyostelium discoideum: ‘slime mold’, social amoeba Motility and chemotaxis (Lectures 4 and 14) Cell adhesion (Lecture 5) Phagocytosis, micropinocytosis, autophagy (Lecture 15) Pattern formation (Lecture 18) Cell death (Lecture 17) [Bozzaro (2019) Int J Dev Biol 63:321-31] Dr Clemens Kiecker Topic title: Cells in their environment 13 Chapter 3 Pathogens Dr Clemens Kiecker Topic title: Cells in their environment 14 Bacterial pathogens Robert Koch (1884): cholera is caused by a rod-shaped bacterium (Vibrio cholerae) Paul Ehrlich (1910): Salvarsan Alexander Fleming (1928): penicillin – Nobel Prize for Medicine 1945 Multi-resistant Staphylococcus aureus (MRSA) Cyanobacteria: produce toxins (BBC 30/September/2020: ‘Elephants die from ‘bacterial disease’’) Archaea are not known to cause diseases Dr Clemens Kiecker Topic title: Cells in their environment 15 Viruses Dr Clemens Kiecker Outside of host cell: virion (DNA or RNA + protein coat/capsid + sometimes lipid envelope) Retroviruses, lentiviruses (e.g. HIV) – integration events can be mutagenic Dormancy (e.g. herpes virus, varicella-zoster virus) 2014 identification of 30,000 year old Pithovirus sibericum Origins: ‘virus first’ versus ‘cellular origin’ hypotheses Usually very small (only visible in EM) 2013 Science: pandoravirus (2,500 genes) Topic title: Cells in their environment 16 Other pathogens Fungi: Candida albicans, Cryptococcus gattii, coccidioidomycosis (‘Valley fever’), athlete’s foot Approx. 1 mio deaths per year globally Protists: malaria, toxoplasmosis, giardiasis (‘beaver fever’), cryptosporidiosis Dr Clemens Kiecker Topic title: Cells in their environment 17 Recommended reading Pollard, Earnshaw, Lippincott-Schwartz, Johnson, Pollard (2017) Cell Biology. 3rd ed. Elsevier, PA. Please note that the content of this book is broader than the learning outcomes of this module. Thus, do not panic – we do not expect you to study this book from the first to the last page. You should rather use it to supplement your learning and as a resource if you have a question or if you find a particular topic interesting and would like to learn a little bit more about it. Dr Clemens Kiecker Topic title: Cells in their environment 18 Thank you for your attention [email protected] © King’s College London. All rights reserved