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BI110 (193)
Chapter 2


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Wilfrid Laurier University
David Smith

Chapter 2 9/19/2012 6:26:00 AM CELL THEORY:  All organisms are composed of one or more cells o Defined by one or more cells o Ex. Bacteria, algae, yeast (Single) o Multi-cellular organisms  The cell is the basic structural and functional unit of all living organisms o Basic unit of life o A cell as a whole unit is necessary to function properly  Cells arise only from the division of preexisting cells o Need genetic information Cells first observed in the 1600’s by Robert Hooke and Anton van Leeuwenhoek  Hook coined the term “cellulae”  Van Leeuwenhoek described bacteria and protists as “animacules” 1800’s  Robert Brown: first to observe the nucleus  Mathias Schleiden: plants are made of cells, and nucleus is important for development  Theodor Schwann: all animals are made of cells  Rudolf Virchow (Robert Remak): cells only arise from pre- existing cells What about “Synthetic Cells”?  First recorded in 2010 o Worked with microplasma o Chemically synthesized the entire genom Cell Diversity: microscopy has been key  Most cells are too small to be seen unaided by the human eye o Comes in many different shapes and sizes o Organized in the same basic plan o Purple pages (F-7) Why aren’t cells bigger?  Surface area-to-volume ratio  Volume determines capacity for chemical activity  Surface area determines the amount of transport in and out  If you double the diameter of a cell, you will increase the volume of the cell by eight times, but you will only increase the amount of surface area by four times. Microscopy  Bright Field o Standard Cell  Dark Field o Light comes in as an angle, then reflected through the cell  Fluorescence o Add a fluorescent dye that binds to the cell  Confocal o Gives more of a 3D image, Sophisticated  Electron o Much higher magnification and radiation  Scanning electron o To get much greater detail in cells Prokaryotes and Eukaryotes  All forms of life are based on two distinct types of cells: Prokaryotic and eukaryotic  Prokaryotic cells lack a nucleus o “Pro” -> before, evolutionarily earlier form of life o Make up two of the domains of life: Bacteria and Archaea  Eukaryotes o “eu” -> True, “karyon” -> nucleus  Share basic features: o Plasma Membrane o Cytoplasm  Cytosol  Organelles  Cytoskeleton o DNA organized into chromosomes o Basic cellular processes:  Electron transport chain  Transcription and translation Characteristics of Eukaryotic Cells are different from Prokaryotic cells:  Separation of DNA and cytosol by nuclear envelope  Presence of membrane-bound compartments with specialized functions  Highly specialized motor proteins  90% of the plant cell is filled with the vacuole Eukaryotic Cells: Distinguishing feature is the presence of a nucleus Organelles  Many are found only in eukaryotes  Why are they important?  They still do exist in prokaryotes Ribosomes  Unifying feature of all cell types (Translation) – Production of protein o Bacterial, archaeal, and eukaryotic are all slightly different  In Eukaryotes, some are free in cytosol, others are attached to endoplasmic reticulum membranes. o Can be localized to two different places in the cell o Still others are found in mitochondria (third location for animal cells and plant cells) and chloroplasts (fourth location for plant cells) Endoplasmic Reticulum (ER)  Extensive interconnected network of membranous channels and vesicles  Rough ER: o Ribosome-studded o Makes protein that become part of cell membranes or are released (secreted) from cell  Smooth ER: o Synthesizes lipids and is the site of many other essential cellular functions  Nuclear Envel
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