1. Cilia and Flagella Who uses these? How Cells Move
How can a cell move with no arms or legs?
Cilia and Flagella
Who uses these?
Unicellular organisms w/o skeletal-muscular systems
Protozoans (unicellular heterotrophic protists) and primitive algae
ciliate
flagellate

2. ATP is used to pull tubes (microtubules)
How Cells Move
How do cilia and flagella work?
ATP is used to pull tubes (microtubules)
9+2
9+0
(9 + 2 arrangement within flagella and cilia; in basal bodies/centrioles)

3. Pseudopodia (create “Fake Feet”)
How Cells Move
What if they have no cilia or flagella (like amoebas)?
Pseudopodia (create “Fake Feet”)
Used by amoeba to move
Cell extensions (no microtubules)
pseudopod

4. Chemotaxis vs. Phototaxis
How Cells Move
How do unicellular organisms know where to move?
Chemotaxis vs. Phototaxis
Chemotaxis – process by which a cell directs their movement depending on a chemical in the environment – taxis = to move (hence the word taxi).
Ex. 1. Movement of sperm towards the egg (egg secretes chemicals that sperm are attracted to);
2.Movement of macrophages to a site of bacterial infection (broken cells release a chemical attractant)
3. Movement of bacteria to a high concentration of glucose
These are all examples of positive chemotaxis (move towards the chemical)
There can also be negative chemotaxis (move away from the chemical).

5. How Cells Move
Phototaxis – process by which an entire organism directs their movement depending the stimulus of light (this is NOT a plant moving towards light, which is called phototropism).
Ex. 1. Algal cell moves toward light (positive phototaxis)
Ex. 2. Moths or fruit flies attracted to light
Movement

6. Think back to the “Why cells don’t grow indefinately” lab.
In your notes, write and answer the following question: If cells can move, why be multicellular?

7. If cells can move, why be multicellular?
Long distance diffusion takes a long time. (so long that cells can die)
Cells need large surface areas for faster diffusion.
Lots of cells together=Lots of Surface Area and very little volume.