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Cell Biology & Genetics: Intro to the Cell
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BIOL10110 Cell Biology and Genetics Prof. Jeremy C. Simpson Lecture 1 Introduction - a tour of the cell Important Info Assoc. Prof. Carl Ng (Module Coordinator & Practicals) Email: carl.ng@ucd.ie Prof. Jeremy Simpson (Introduction to Cell Biology) Email: jeremy.simpson@ucd.ie Assist. Prof. Paola Valentini (Cell Biology lectures) Email: paola.valentini@ucd.ie Prof. Emma Teeling (Genetics lectures) Email: emma.teeling@ucd.ie Prof. Jeremy C. Simpson SBES, UCD-Dublin General Module Queries Email: BIOL10110@ucd.ie Today’s lecture ... What is cell biology? How do we study cells? What are the different types of cells? What are the main features of cells? What is inside cells? Prof. Jeremy C. Simpson SBES, UCD-Dublin The beauty of studying cells Cells are the basic unit of all forms of life on our planet and exist in a variety of forms. The discipline of cell biology seeks to understand how cells work in the context of entire organisms. What is cell biology ? Cell biology serves to understand how our genes, and specifically their gene products (proteins), regulate health through the cells in which they work https://www.utmb.edu Genes & Molecules Cells Organisms Why cell biology ? All disease can be attributed to dysfunction of specific molecules in certain cell types – cell & molecular biology serves to understand this https://pages.wustl.edu Visualising cells to understand their function is essential What is cell biology ? Genetics Molecular biology Biochemistry Bioinformatics Cell biology Systems biology Microbiology & Virology Developmental biology Zoology Prof. Jeremy C. Simpson SBES, UCD-Dublin Botany Physiology Medicine and health What is cell biology ? Cell biology • all organisms are made of cells • the cell is the simplest collection of matter that can be alive • cell structure is correlated to cellular function • all cells are related by their descent from earlier cells Prof. Jeremy C. Simpson SBES, UCD-Dublin How do we study cell biology ? Cell fractionation Understanding each part allows understanding of the whole • cell fractionation takes cells apart and then centrifugation separates them into their component parts • cell fractionation enables scientists to determine the functions of individual cellular components • biochemical techniques help correlate cell function with structure Prof. Jeremy C. Simpson SBES, UCD-Dublin How do we study cell biology ? Cell fractionation homogenisation cells supernatant homogenate centrifugation (slow, fast, faster, ...) supernatant pellet etc. pellet pellet Prof. Jeremy C. Simpson SBES, UCD-Dublin How do we study cell biology ? Microscopy Observing the whole can help our understanding of each part • scientists use microscopes to visualise cells too small to see with the naked eye • in a light microscope (LM), visible light is passed through a specimen and then through glass lenses • lenses refract (bend) the light, so that the image is magnified • in an electron microscope (EM), electrons are used instead of light, and magnets control the electron beam Prof. Jeremy C. Simpson SBES, UCD-Dublin How do we study cells ? Microscopy 1870s 1660s Prof. Jeremy C. Simpson SBES, UCD-Dublin 2000s Molecules, cells and organisms - size matters! 10 m 0.1 m Length of some nerve and muscle cells Chicken egg 1 cm 1 mm 100 µm Prof. Jeremy C. Simpson SBES, UCD-Dublin Frog egg Human egg Unaided eye 1m Human height Molecules, cells and organisms - size matters! 1 cm 1 µm 100 nm 10 nm 1 nm 0.1 nm Prof. Jeremy C. Simpson SBES, UCD-Dublin Most bacteria Mitochondrion Smallest bacteria Viruses Ribosomes Proteins Lipids Small molecules Atoms Superresolution microscopy Electron microscopy 10 µm Most plant and animal cells Light microscopy 100 µm Human egg Unaided eye 1 mm Frog egg Model organisms – cells, cells and more cells for cell biology Fungi Animals Saccharomyces cerevisiae (baker’s yeast) Caenorhabditis elegans (nematode) Drosophila melanogaster (fruit fly) Size: ca. 3-4µm Genes: ca. 6,200 Size: ca. 1mm Genes: ca. 20,000 Size: ca. 2.5mm Genes: ca. 14,000 Plants Mus musculus (house mouse) Homo sapiens (human) Size: ca. 10cm* Genes: ca. 22,000 Size: ca. 1.8m Genes: ca. 22,000 Arabidopsis thaliana (thale cress) Size: ca. 10cm Genes: ca. 27,000 Prof. Jeremy C. Simpson SBES, UCD-Dublin Prokaryotic versus eukaryotic cells • basic features of all cells – plasma membrane – semifluid substance called cytosol – chromosomes (genes / DNA) – ribosomes (make proteins) DNA plasma membrane ribosomes cytosol • prokaryotic (bacterial) cells are characterised by having – no nucleus – DNA in an unbound region called the nucleoid – no membrane-bound organelles Prof. Jeremy C. Simpson SBES, UCD-Dublin Prokaryotic versus eukaryotic cells fimbriae nucleoid ribosomes plasma membrane cell wall bacterial chromosome capsule flagella A typical rodshaped bacterium Prof. Jeremy C. Simpson SBES, UCD-Dublin 0.5 µm A thin section through the bacterium Bacillus coagulans as seen by transmission EM Prokaryotic versus eukaryotic cells • eukaryotic cells are characterised by having – DNA in a nucleus that is bounded by a membranous nuclear envelope – membrane-bound organelles – cytoplasm in the region between the plasma membrane and nucleus • eukaryotic cells are generally much larger than prokaryotic cells cell cytoplasm nucleus 30 µm Animal Cells Human cells from lining of uterus (colourised TEM) Prof. Jeremy C. Simpson SBES, UCD-Dublin In complex organisms cells are organised into tissues and organs BC Open Text Books Prokaryotic versus eukaryotic cells So in infection, what happens when a bacterial (prokaryotic) cell enters an animal (eukaryotic) cell? plasma membrane nucleus cytoplasm Initially Listeria bacteria can be seen ‘swimming’ rapidly inside this human cell Occasionally they attempt to push out from this cell and infect the neighbouring cell Finally, you will see how fluorescence microscopy and then computational modelling can be used to visualise these infection events in living cells Prof. Jeremy C. Simpson SBES, UCD-Dublin Eukaryotic cells So, there is a lot of things going on inside cells … … studying them to understand their function is important, particularly in terms of infection and disease … … so, let’s take a closer look inside ….. Prof. Jeremy C. Simpson SBES, UCD-Dublin Typical animal cell - schematic eukaryotic cells are surrounded by a plasma membrane, which is a selective barrier that allows sufficient passage of oxygen, nutrients, and waste to service the volume of the cell eukaryotic cells have internal membranes that partition the cell into organelles the general structure of a biological membrane is a double layer of phospholipids outside inside Prof. Jeremy C. Simpson SBES, UCD-Dublin 0.1 µm phospholipids proteins Inside a eukaryotic cell Please watch these two videos – provided in Brightspace Prof. Jeremy C. Simpson SBES, UCD-Dublin Typical animal cell - by microscopy endoplasmic reticulum nucleus lysosomes transport vesicles Electron microscope Light microscope 5µm Prof. Jeremy C. Simpson SBES, UCD-Dublin nucleus cytoskeleton microtubules 5µm peroxisome Microscopy reveals the complexity of the subcellular environment in intact cells mitochondria Typical animal cell - schematic endoplasmic reticulum (ER) flagellum rough ER smooth ER centrosome nuclear envelope nucleolus chromatin nucleus plasma membrane cytoskeleton actin filaments intermediate filaments microtubules ribosomes microvilli Golgi apparatus peroxisome Prof. Jeremy C. Simpson SBES, UCD-Dublin mitochondrion lysosome This compartmentalisation within eukaryotic cells is essential for their function Typical plant cell - schematic nuclear envelope nucleus nucleolus chromatin rough endoplasmic reticulum smooth endoplasmic reticulum ribosomes central vacuole Golgi apparatus actin filaments intermediate cytoskeleton filaments microtubules mitochondrion peroxisome chloroplast plasma membrane cell wall wall of adjacent cell Prof. Jeremy C. Simpson SBES, UCD-Dublin plasmodesmata This compartmentalisation within eukaryotic cells is essential for their function The importance of studying intact cells - basic functional unit of life - capable of duplication - dynamic Typical animal cell - capable of acquiring and using energy - can have specialised functions - carry out specific chemical reactions - engage in mechanical activities - respond to stimuli Typical plant cell Prof. Jeremy C. Simpson SBES, UCD-Dublin - functional units of organs - understanding disease and infection Cells are responsible for everything that we do! Next lecture We will find out more about the internal structures and organelles inside eukaryotic cells ... Prof. Jeremy C. Simpson SBES, UCD-Dublin
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