- The cytoskeleton is a network of fibers extending throughout the cytoplasm and it helps to hold the cells shape together.
- They are the "muscles" for movement.
- The three types are microfilaments, intermediate filaments, and microtubules.
- Helical rods made out of a globular protein called actin.
- These help the cell move and change their shape.
- Actin and other fibers work together to make muscles contract.
- These are ropelike fiberous proteins.
- They have reinforced rods to bear tension and they anchor organelles.
- Straight, hollow tubes that are made of globular proteins. They are called tubulins.
- Globular molecules are like small marbles.
- They make themselves longer by adding tubulin subunits to one end.
- Their functions are providing shape, tracks for organelles to move within teh cytoplasm, they guide the movement of chromosomes during cell division, and move the cilia and flagella.
- Shorter than flagella and they are more numerous.
- Propel protists; single celled organisms.
- Can be damaged by smoking and line the respiratory tract.
- The cilia push debri up and out of the body.
- A type of transport.
- Propel sperm, other animals, and protists.
- Microtubules form a 9 + 2 arrangement which means that there are 9 doubles of microtubules forming a ring around one double.
- These make up one cilia or one flagella
- To move the cilia or flagella, a motor protein called dyneins is needed. It grabs ontioo an adjacent microtubule doublet.
- These structures are flexible.
- Basal bodies and centrioles have identical structures.
- Basal bodies are anchor cilia or flagella in the cytoplasm.
Membranes of the Cell
- Plasma Membrane - cell's outer membrane (Cell Membrane)
- Endomembranes - smooth and rough endoplasmic reticulum, golgi, vacuole, and lysosome (only these internal oragnelles can break apart)
- Membranous envelopes - nucleus, chloroplast, and mitochodria (have 2 membranes)
- Semi-permeable - allow some substances to pass through, but blocks the passage of other substances. (only small things can go through)
- Membranes enclose and maintain the specific chemical environment.
- Every membrane carries out its specific functions.
- Two layer membrane called phospholipid bilayer.
- Made of proteins and lipids
- Contains two fatty acids instead of three (hydrophobic)
- Contains a phosphate group in the place of the third fatty acid (hydrophilic)
Membranes and Proteins
- Specific proteins are inserted into the phosolipid bilayer to:
- Attach to the cytoskeleton
- Talk to other cells
- Enzyme Activity
- Transporting passively and actively
- Two cells holding each other, intercellular joining
- Cell-cell recognition
- Membranes are not rigid.
- Protiens move freely on the membrane and do not just stay in one spot.
- This is called the fluid mosaic model.
Diffusion and Osmosis
- In diffusion, the molecules move.
- In osmosis, the water moves.
- Diffusion: the tendency of molecules to move from a high concentration to a low concentration until equilibrium is reached.
- Equilibrium is when the conecentration of either side it equal.
- Diffusion across a membrane.
- Cell does not use any energy for diffusion.
- Selectively permeable membrane.
- Water, O2, and CO2 go through the membrane because they are small.
- Osmosis: passive transport of water across a semi-permeable membrane.
- Solute = what is dissolved.
- Solvent = what the solute is dissolved in.
- Water moves across the membrane, not the solute.
- High concentration of solute and lower for solvent.
- Hyper = above.
- Plasmolysis = losing water.
- Cells will shrivel up if there is not enough water.
- High concentration of solvent and lower for solute.
- Hypo = below.
- Lysing = bursting of a cell.
- Good for plant cells.
- Everything is equal.
- Isos = equal.
- Animal cells like this, but plant cells do not.
Effect on living animal cells
- Osmoregulation - control of water balance.
- Animals must use this to survive.
- Blood cells love this.
Effect on living plant cells
- Most plants thrive in a hypotonic environment when the vacuole is full.
- Plants become wilted in a isotonic environment.
Posted on 10/4/2010
Next Scribe: Katie B.