Oct. 3, 2011

Today we finished the notes on the cytoskeleton and began notes on the cell membrane. There is a quiz tomorrow on everything we've learned so far in the section. There is also a lab tomorrow. The homework is to read pages 37-39 in our UP and draw a picture of the lab.

Here are some basic overviews of what we learned.

Intermediate Filaments

• ropelike protiens
• anchor organelles

Microtubules

• straight, hollow tubes made of protiens called tubulins
• provide rigity and shape to the cell
• tracks for organelle movement
• guide chromosome movement in cell division
• move cilia and flagella

Cilia-propel protists

Flagella-propel some types of cells, long "tail"

Microtubule structure

• form a 9+2 arrangementto
• to move cilia or flagella, dyniens grap onto an adjacent microtubule doublet
• basal bodies and centrioles have identical structures

Plasma Membrane

membranes of a cell

• plasma membrane-outer membrane
• endomembranes-smooth and rough ER, golgi, vacuole,lysosome
• membraneous envelope-nucleus chloroplast mitochondria

membrane features

• semi-permeable, allow some substances to pass through, but not others

membrane structure

• two layer membrane called phospholipid bilayer, composed of protien and lipids
• lipids called phospholipids
• contain 2 fatty acids, not 3, fatty acids are hydrophobic
• contain phosphate groub in place of 3rd fatty acid

flexibility

• membranes not flexible, rigid
• protiens move freely in membrane plane
• called fluid mosaic

diffusion and osmosis

diffusion-the tendency of molecules to move from a higher concentration to a low concentration until equilibreum is reached

Passive transport

• diffusion across a membrane
• cell uses no energy
• selectively permeable membrane
• osmosis-passive transport of water across a semipermeable membrane
• in osmosis water moves across membrane not the solute

Hyper tonic-solution with a higher concentration of solute and a lower concentration of water

hypotonic- solution wit ha lower concentration of solute and a higher water concentration

isotonic-solution with equal solute concentration

Effect on living animal cells

• osmoregulation-control of water balance
• animals must use this when exposed to hypertonic or hypotonic environments
• fish use gills and kidneys to keep too much water out

Effect on living plant cells

• most plants thrive in a hypotonic environment when there is more water
• plants become wiltedin isotonic environment

next-Dana