Tuesday, December 13, 2016

Monday, April 18, 2016

55.1 Energy flow


55.4 Nutrient Cycles





Taking Notes: typing or writing?

A little something to think about when you are trying to decide between hand writing or typing your notes.

http://www.npr.org/2016/04/17/474525392/attention-students-put-your-laptops-away?utm_source=facebook.com&utm_medium=social&utm_campaign=npr&utm_term=nprnews&utm_content=20160417

Monday, March 28, 2016

Terrestrial Biomes 52.2 - Austin

If you missed Austin's Terrestrial Biomes presentation or need to refer back to it, I have uploaded it to google docs.  Click here to take a shortcut.


Wednesday, March 2, 2016

47.3 Cell Fate Blog Post

Cell Fate Specification

Definitions:


  • Differentiation—changes involved in the progressive diversification of the structure and function of cells Acquisition of the characteristics that allow different cell types to perform their functions.
  • Cell fate—what a cell will become (if left alone).
  • Potency—what a cell could become
  • Commitment—restriction in potency
  • Specification—labile state where a cell has reversibly acquired fate (potency > fate)
  • Determination—state where a cell has irreversibly acquired fate (potency = fate)
  • Determinant—a molecule that regulates cell fate
  • Morphogen—a molecule forms a gradient and regulates cell fate in a concentration dependent manner. 

I. Types of Specificaton


  1. Autonomous Specification 
    • Remove a cell and the cell types normally derived from that cell will not form.
    • Isolate a cell and it will form the cell types it normally would have.
  2. Conditional Specification
    • Remove a cell and the cell types normally formed by that cell will be contributed by other cells (compensation) 
  3. Syncitial Specification
    • Important in insects

II. Autonomous Specification 


  • Asymmetric distribution and inheritance of determinants 
  • Determinants typically cytoplasmic 
  • Determinants usually RNAs or proteins
    1. MACHO mRNA localized in yellow cytoplasm of tunicate embryo 
      • Antisense blocks muscle formation (=necessary)
      • Injected mRNA induces animal pole to form muscle (=sufficient) 
    2. SKN-1 protein localized in C. elegans EMS cell (pharynx derived from EMS) 
      • skn-1 loss-of-function mutant produces no pharynx (necessary)
  • Fucus contains cell wall determinants (handout)

III. Conditional Specification 


  • A cell’s fate is determined by its environment 

A. Cell interactions.

  • Contact with neighboring cells influence cell fate e.g. sea urchin 
    • Animal pole cells alone produce ectoderm only
    • Animal pole cells plus micromeres produce cell types normally derived from vegetal pole cells 
  • Stem Cells—cells that divide to maintain a self-renewing population, and contribute daughters that will differentiate. Can get progressive commitment. 

Thursday, February 11, 2016

40.3- Thermoregulation

40.3- Thermoregulation
·         Regulation of internal temperature
·         Endothermy- warmed by the heat of metabolism , internal heat source (humans)
o   Need more food
·         Ecothermy-  warmed by environment, external heat source (reptiles)
o   Need less food because food is scarce
o   Larger fluctuation in body temperature
o   Regulate body temperature by moving to shading and basking
·         Variation in body temperature
o   Poikilotherms
§  Variation, body temp varies with environment
o   Homeotherms
§  Same, constant body temp

o   Never use warm-blooded or cold- blooded
·         Balancing heat Loss and Gain
o   Figure 40.11
o   Integumentary (Skin)
§  Insulation- fat, hair, feathers
§  Circulatory Adaptation- vasoconstrictions, vasodilation
§  Countercurrent Exchanges
§  Cooling by Evaporation
          ·         Heat or Loss
§  Behavior Response
          ·         Migration, Hibernation
§  Adjusting Metabolic Heat Production
            ·         Vary heat production to match changing rates of heat lose
             o   Shiver
§  Acclimatization in Thermoney
·         Shedding
·         Changes in Lipids