Friday, September 19, 2008

Today In Biology We...
  1. took a quiz
  2. Curtis lied about the quiz result charts being fixed
  3. got our labs back
  4. learned about the one tracked minds of boy's sperm
  5. took some notes
  6. played a fun revealing-thinger game

Here are the notes that we took today!

THE CYTOSKELETON

cytoskeleton- a network of fibers throughout the cytoplasm that forms a dynamic framework for support and movement and regulation.
  • gives mechanical support to the cell and helps maintain its shape.
  • enables a cell to change shape in an adaptive manner
  • associated with motility by interacting with specialized proteins called motor molecules
  • plays a regulatory role bu mechanically transmitting signals from cell's surface to it's interior

The 3 types of fibers in the cytoskeleton are shown above in the beautiful picture and explained below

microtubules- straight hollow fibers about 25nm in diameter and 200nm in length; constructed from the globular proteins called tubulin. Examples would include:
  • centrioles: pair of cylindrical structures located in the centrosomes of an animal cell, composed of nine sets of triplet microtubules arranged in a ring.


  • cilia and flagella: locomotor oraganelles found in eukaryotic cells that are formed from a specialized arrangement of microtubules.


microfilaments- also called actin filaments; provide cellular support; participate in muscle contraction; and responsible for localized contraction of cells
  • helps with the elongation and contaction of psuedopodia druring amoeboid movement
intermediate filaments- (8-12nm) between microtubules and microfilaments; constructed from keratin subunits; fix organelle position; reinforce cell shape; bear tension


CELL SURFACES AND JUNCTIONS

Plant cells produce coats external to the plasma membrane.

cell wall-protects the plants and gives support; contains cellulose

extracellular matrix- (EMC) meshwork of marcomolecules outside the plasma membrane of animal cells, locally secreted by cells; provides support and anchorage fro the cells

plasmodesmata- channels that perforate plant cell walls through which cytoplasmix strands communicate between adjectent cells.

tight junction-intercellular junction that holds cells together tightly enough to black transport of substances through the intercellular space.

desosomes- intercellular junctions that rivet cells together into strong sheets, but still permit substances to pass freely

gap junction-intercellular junction specialized fro material transport etween the cytoplasm of adjacent cells.


Okay that's it! Don't forget about your vocab this weekend!

2 comments:

SMABiology said...

great use of the textbook images. Very thorough. Your cytoskeleton image actually showed the mitochondria and other organelles suspended just like the question on the quiz today.

Meghan Colip said...

Thanks Meg (right?) :) after being away this really helped me prepare for my make up quiz- great job!