Haverford College is a private, coeducational liberal arts college located in Haverford, Pennsylvania, a suburb of Philadelphia.
|
http://www.haverford.edu/library/special/scap
|
|
|
|
Asymmetric division
Asymmetric division
Text and image sources are included using the notes function of this file
Using the same structural elements of a symmetric mitosis, some cells divide asymmetrically, creating two daughter cells that may assume very different developmental fates. This process is fundamental to development in metazoans, from the first divisions of the embryo though neural development and stem cell-based tissue renewal.
http://www.welc.cam.ac.uk/~brandlab/images/images.html , cached 040225
Green, fixed Tau-GFP; Red, anti-Eve; Blue, anti-FasII
|
|
|
|
The Endomembrane System
The Endomembrane System
Text and image sources are included using the notes function of the .ppt file
The focus of this chapter of our hypertext will be on the endomembranes of the eukaryotic cytosol
Endoplasmic Reticulum; Golgi; Lysosomes; Peroxisomes; and their dynamic interconnections.
Flow of material through the endomembrane system is both anterograde (outward directed, toward the cell surface) and retrograde (inward directed, from the cell surface); each compartment has its resident proteins as well. Delivery from the ER supplies these compartments, as well as the cell surface, with lipids and protein components.
Internal compartmentation by semi-permeable membranes permits
Accumulation / exclusion / microenvironments / non-compatible biochemistries
http://www.olympusmicro.com/primer/techniques/fluorescence/gallery/cells/apm/apmcellslarge.html , cached 060122
A pseudocolored image of African water mongoose cells showing labeling of the nuclear pore complexes (green), the microfilament cytoskeleton (blue) and Golgi (magenta; the specific antigen is “giantin”, a structural protein of the Golgi).
|
|
|
|
Organizing the cell: the Cytoskeleton
Organizing the cell: the Cytoskeleton
Microtubules Microfilaments Intermediate Filaments
The Cytoskeleton:
is composed of complementary, filamentous polymer systems
serves to shape and support cells (and, in multicellular organisms, tissues), offering strength and resiliency
can be static or dynamic, and is actively remodeled, specially during division
functions in movement (cell locomotion and intracellular transport), especially as tracks for molecular motors
Images are from http://cellix.imolbio.oeaw.ac.at/Videotour/video_tour_1.html , cached 060127
Microtubule cytoskeleton labeled with an antibodies to tubulin; actin cytoskeleton, labeled with fluorescent phalloidin; and the intermediate filament cytoskeleton labeled with antibodies to the intermediate filament protein, vimentin. Listed as from (Herzog et al., 1994) but full reference is not given.
|
|
|
|
The Organelles: Mitochondria and Chloroplasts
The Organelles: Mitochondria and Chloroplasts
Text and image sources are included using the notes function of the .ppt file
This chapter of our hypertext will focus upon the structure of the two primary classes of eukaryotic cytoplasmic organelles: mitochondria and chloroplasts.
Spyrogyra image from http://www.microscopyu.com/galleries/dxm1200/algaesmall.html , cached 060118
Differential interference contrast image of spiral chloroplast arrays in a filamentous green alga
|
|
|
|
Microtubule motors
Microtubule motors
Text and image sources are included using the notes function of this file
Traffic through the cell is carried by a myriad of motor molecules. For microtubule-based transport, kinesins and dyneins are responsible for linking energy release from ATP hydrolysis to movement. Individual motor velocities can exceed 2-4 um/sec.
Dyneins are all minus-end directed motors, whereas most (but not all!) kinesins are plus-end directed motors.
Movement of material toward the plus ends of microtubules is called anterograde transport, whereas minus end-directed movements are referred to as retrograde. The overall polarity of the cytoskeleton is “read” by the uniform orientation of tubulin dimers in each individual polymer, promoting global delivery to the cell surface or deep cytoplasm.
http://www.sciencemag.org/cgi/content/full/279/5350/519/F4 , cached 040203
|
|
|
|
Microfilaments
Microfilaments
Text and image sources are included using the notes function of this file Microtubules Microfilaments
In this chapter of our web text, we will examine the architecture of the Actin Microfilament Cytoskeleton.
Microfilaments are polymers of actin subunits, and can comprise 1-10% of total cell protein (0.1-0.5uM)
http://www.biology.purdue.edu/research/groups/motility/gallery/pages/3neurons.htm , cached 070213
Showing three neuronal cells in culture, stained for microtubules (green) and microfilaments (red) emphasizing the role of the actin cytoskeleton in the extending processes of each cell.
|
|
|
|
Origins of Multicellularity
Origins of Multicellularity
Chlamydomonas Gonium Pandorina
Eudorina Pleodorina Volvox Structural Progressions in Colonial Green Algae “The Volvocine Lineage”
As we move from single-celled organisms to multicelled organisms, we need to consider a big question - WHY? Life emerged about 3.5 billion years ago (BYA), eukaryotic organisms about 2 BYA, and multicellularity about 1 BYA (around the divergence of the plant and animal lineages).
In order to form multicellular organisms, cells needed to stay together after mitosis and typically exhibit some functional division of labor, typically a split between the soma (body) and the reproductive germ line (gonads/gonidia).
Different levels of cooperation are observed among different green algae, ranging from single cells such as Chlamydomonas (A) to cooperating groups of clonally-derived cells that function together, as in Pandorina (C) and Eudorina (D). Volvox (F) consists of a flagellated colony of several thousand cells that forms daughter colonies as well as gametes internal to the colonial sphere. Division of labor, protection and provisioning of offspring all become possible as the soma grows larger and more elaborate. Diversification is an investment strategy pursued by multicellular life forms offering evolutionary benefits (to draw on an Economics model). This human construct of the “Volvocine Lineage” was originally based upon a speculative anatomical comparisons, but has been supported by phylogenetic analyses of the green algae.
The evolution of multicellularity as a life strategy also may have been driven by cheaters (remember Dictyostelium) - in forming an integrate...
|
|
|
|
Drosophila melanogaster
Drosophila melanogaster
2.5mm Movie
This chapter of our on-line text will focus on Drosophila melanogaster, the Fruit Fly.
Drosos and phila is from the Latin meaning dew loving, and melanogaster means black-bellied
Females are slightly larger (2.5 mm) than males; a female can lay up to 500 eggs in 10 days.
http://en.wikipedia.org/wiki/Drosophila_melanogaster cached 060412
http://en.wikipedia.org/wiki/Drosophila cached 060412
Crawling larva http://www.salk.edu/labs/mnl-t/clh/CLH%20images/c110.jpg cached 070419
Other on-line resources:
FlyBase at http://flybase.bio.indiana.edu/
FLY-MORPH-O-GENESIS at http://sdb.bio.purdue.edu/dbcinema/kaufman/kaufman.html
The Interactive Fly http://www.sdbonline.org/fly/aimain/1aahome.htm
|
|
|
|
Module 4: Science, Technology, and Education
Module 4: Science, Technology, and Education
Science and technology education from diverse perspectives
Science education controversies
Information technology and education
Women and science education
Race and science education
|
|
|
|
|
Health Reform Gerard Anderson
Professor
Johns Hopkins
|
|
|
|
