BIOL111 Week 9 Lecture 1_upload.pdf

BIOL111/BCHM111 Lectures 24-35: Cell Biology Vanessa Morris [email protected] Julius von Haast (Biology Building) Room 422 ON LEARN ON LEARN Questions? Shout out or use padlet: http://canterbury.padlet.org/vanessamorris/BIOL111 Today’s Outline 1. Cell biolo...

BIOL111/BCHM111 Lectures 24-35: Cell Biology Vanessa Morris [email protected] Julius von Haast (Biology Building) Room 422 ON LEARN ON LEARN Questions? Shout out or use padlet: http://canterbury.padlet.org/vanessamorris/BIOL111 Today’s Outline 1. Cell biology and the discovery of cells 2. What is a cell? Three tenets of Cell Theory 3. Categorizing living organisms: the three domains of life 4. Different types of cells: prokaryotes and eukaryotes 5. How do we study cells?  1. What is Cell Biology? Cell biology is the study of the structure and function of the cell, which is the basic unit of life structures and organelles life cycle cell behaviour interactions Cell biology relates to molecular biology, physiology, biochemistry, microbiology and immunology. *Reece et al. (2011) Campbell Biology, 9th ed, Fig. 6.2  The History of Cells 50x The term “cells” was coined in 1665 by Robert Hooke (1635-1703). What did Hooke see that he called cells? Micrographia: or some Physiological Descriptions of Minute Bodies Made by Magnifying Glasses with Observations and Inquiries thereupon, Robert Hooke, 1665; Harris (1999) The Birth of Cells  The History of Cells The term “cells” was coined in 1665 by Robert Hooke (1635-1703). Slices through cork show the patterns of the cell walls of dead cells. Micrographia: or some Physiological Descriptions of Minute Bodies Made by Magnifying Glasses with Observations and Inquiries thereupon, Robert Hooke, 1665; Harris (1999) The Birth of Cells  The History of Cells 275x van Leeuwenhoek (1632 - 1723) Harris (1999) The Birth of Cells  The History of Cells van Leeuwenhoek discovered “animalcules” were bacteria and “animacules” in the late 1600s other single-cell organisms Harris (1999) The Birth of Cells  The History of Cells Schwann Schleiden animals plants Mikroskopische Untersuchungen über die Üvereinstimmung in der Struktur und den Wachstum der Thiere und Pflanzen (1839) Th. Schwann  2. What is a cell? Cell Theory Cell theory contains three premises. 1) All organisms are composed of one or more cells. From English Wikipedia. Live Ammonia tepida benthic foraminiferan collected from San Francisco Bay. Phase-contrast photomicrograph by Scott Fay, UC Berkeley, 2005. Sequoia sempervirens  Cell Theory Cell theory contains three premises. 2) Cells are the smallest living units of all living organisms. Other structures may exist within cells, but the cell is the base structure. An animal cell Reece et al. (2011) Campbell Biology, 9th ed, Fig. 6.08  Cell Theory Cell theory contains three premises. 3) Cells arise only by division of a previously existing cell. Raspail stated in 1825 that “Omnis cellula e cellula” Every cell derives from a pre-existing cell. http://en.wikipedia.org/wiki/Raspail 2. What is a cell? Cell Theory Cell theory contains three premises. 1) All organisms are composed of one or more cells. 2) Cells are the smallest living units of all living organisms. 3) Cells arise only by division of a previously existing cell.  3. Categorising organisms: The Tree of Life How would you separate these 3 organisms on the tree of life? Reece et al. (2011) Campbell Biology, 9th ed, Fig. 26.21  Categorising organisms: three domains of life Three domains All these organisms are made of cells, and the principles of cell theory hold with all of them. Mycobacterium tuberculosis National Institute of Allergy and Infectious Diseases Dennis Kunkel Micoscopy/Science Source Reece et al. (2011) Campbell Biology, 9th ed, Fig. 26.21  Archaea Archaean microbes survive in extreme environments: volcanic hot springs at Rotorua, salt lakes and underwater sea vents. Methanobrevibacter Haloquadratum smithii walsbyi Eukaryotic versus Prokaryotic Cells The three domains of life show fundamental biochemical differences. Similarities between Archaea and Eukarya Unique to Archaea Reece et al. (2011) Campbell Biology, 9th ed, Table 27.2 Domains of life Eukarya and Archaea share a more recent common ancestor Reece et al. (2011) Campbell Biology, 9th ed, Fig. 26.21 4. Different cell types Eukaryotes Prokaryotes Reece et al. (2011) Campbell Biology, 9th ed, Fig. 26.21 Eukaryotic versus Prokaryotic Cells Prokaryotic - Cells lacking a nucleus. Eukaryotic - Cells containing a nucleus. from Greek ευ (eu) means good or true κάρυον (karyon) meaning "nut" refers to the nucleus. Eukaryotic versus Prokaryotic Cells Prokaryote Eukaryote Lack a nucleus Have a nucleus circular chromosomes linear chromosomes no organelles organelles smaller larger not multicellular can be multicellular Eukaryotic versus Prokaryotic Cells Prokaryote Eukaryote Lack a nucleus Have a nucleus Bacteria Unicellular Animals Multicellular Archaea Unicellular Fungi Multi or unicellular Plants Multicellular Protists Mostly unicellular Plasmodium falciparum National Institute of Allergy and Infectious Diseases Flickr What makes up a cell? Eukaryotic versus Prokaryotic Cells Prokaryotes are generally small. Reece et al. (2011) Campbell Biology, 9th ed, Fig. 26.21  Not cells: Viruses Viruses are very small. They are packages of DNA (or RNA) surrounded by a protein coat. They lack a membrane and are not cells. They “live a borrowed life” – require cells to replicate Generally not considered living organisms. 5. How do we study cells?  Light microscopy Important parameters in microscopy: magnification resolution contrast Tricks are often used to increase contrast Cells may be living or dead (fixed) Fluorescence microscopy Can be used to study location of specific molecules/proteins in the cell Resolution of light microscopy is limited by the wavelength of light to ~0.2 µM 3. How do we study cells? Instead of focusing visible light on a sample, electrons are focused on the sample Electron microscopy Electron microscopy Scanning electron Transmission microscopy electron microscopy (SEM) (TEM)  Scanning electron microscopy Study surfaces of objects by (SEM) measuring the scattered electrons Fibroblasts Pollen Samples need to be coated with a conductive material Samples are dead Image by Tescan  Transmission electron microscopy Electrons are passed through a (TEM) sample and the transmitted electrons are detected Cells are dead Centriole Bacteriophage Image by Carina Buttner, Laboratory of Dr. Alan Davidson Immunity. 2017 Jun 20; 46(6): 943–956. Intro to Cell Biology: Key Points Cell Biology - the study of cells, their structures and organelles, their physiology and life cycle. Cell theory states that: 1) All organisms are composed of one or more cells. 2) Cells are the smallest living units of living organisms. 3) Cells arise only by division of a previously existing cell. Across life, 3 domains are recognised: 1) Bacteria 2) Archaea 3) Eukaryota Eukaryotes are distinct from prokaryotes as they contain a nucleus, have organelles and can be multicellular. Microscopy is used to study cells and sub-cellular structures