Introduction to the Study of Cell Biology.docx

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University of Toronto Scarborough
Biological Sciences
Rene Harrison

Introduction to the Study of Cell Biology o Cell biology started off with the invention of the microscope. The microscope is an instrument that provides a magnified image of a tiny object  Robert Hooke (1665) – is credited for the discovery of cells. He attempted to answer: why stoppers made of cork were so well suited to holding air in a bottle. He examined a cut piece of cork under a microscope and perceived what appeared to be pores which he labeled as “cells”  Anton van Leeuwenhoek (1665-1675) – spent spare time grinding lenses and constructing simple microscopes of remarkable quality. He was the first to examine a drop of pond water under a microscope. He was able to observe teeming microscopic “animalcules” that darted back and forth before his eyes.  He was also the first to describe various forms of bacteria, which he obtained from water in which pepper had been soaked and from scraping of his teeth.  Matthias Schleiden (1938), Theodor Schwann (1839), and Rudolf Virchow (1855) – came up with what is known as the cell theory 1. All organisms are composed of one or more cells 2. The cell is the structural unit of life for all organisms 3. Cells can arise only by division from a preexisting cell o The basic properties of cells include: 1. Cells are highly complex and organized 2. Cells possess genetic program and the means to use it 3. Cells are capable of producing more of themselves – through process of mitosis or meiosis 4. Cells acquire and utilize energy to develop and maintain complexity  Example: photosynthesis + respiration (sun  carbohydrates  ATP) 5. Cells carry out many chemical reactions  Enzymes (proteins) use ATP to speed up reactions within cells 6. Cells engage in numerous mechanical activities  Intracellular transport (inside cell) and cell migration 7. Cells are able to respond to stimuli  External signals  via surface receptors (protein) 8. Cells are capable of self-regulation  The means to avoid errors or mistakes  Example: DNA repair enzymes, or immune cells 9. Cells evolve  Beneficial genetic mutations/cellular changes will be kept/retained in future generations o A prokaryote (pro- before; karyon –nucleus)  All bacteria, cyanobacteria (blue-green algae)  Structurally simpler and have been on earth for 3 billion years  Over 1 billion years before first eukaryotes  They do not have a nucleus or a barrier o A eukaryote (eu- true; karyon –nucleus)  Protists, fungi, plants, animals  Structurally more complex o The evolution of eukaryotes – eukaryotic cells are believed to be descended from prokaryotic cells  Believed to have arisen from endosymbionts  An emdosymbiont is a combination of two cells living in a symbiotic relationship with one of the cells resident inside the other one  Thus the notion that 2 prokaryotes cells created a eukaryotic cell a. In step 1: a large anaerobic, heterotrophic prokaryote takes in small aerobic prokaryote b. In step 2: the aerobic endosymbiont has evolved into a mitochondria c. In step 3: a portion of the plasma membrane has invaginated and is seen in the process of evolving into a nuclear envelope and associated endoplasmic reticulum d. In
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