Eukaryote Cytoskeleton and Movement : BIOL 107

Lec 19 and lec 20

Cytoskeleton structure

protein fibers

Cytoskeleton function

maintains cell shape and move cell

Microtubules structure

Tubes made with round Tubulin proteins // heterodimer

assembly and disassembly of MT

added and removed from plus (active) end

MT location

in animal cells grow from the centrosome ("centre body")

Actin filaments (F-Actin) structure

Rods made with round Actin proteins

Subunit protein (F-Actin)

Globular protein

Protein fiber (F-Actin)

Actin filament

Assembly and disassembly of F-Actin

added and removed from both ends

F-Actin location

Cell cortex (inside plasma membrane)

Intermediate filaments structure

Ropes made with thin Keratin proteins

Assembly and disassembly of IF

Keratins connect to each other all at once // build or destroy

Location of IF 1

in cytosol // connect desmosomes

Location of IF 2

in nucleus // line inside of nuclear envelope (lamina)

In animal cells what resists compression

microtubules

In animal cells what resists tension

intermediate filaments

In plant cells what resists compression

the water pressure inside the central vacuole

How do WBC chase bacteria? (proteins required)

G-Actin and F-Actin

How do WBC chase bacteria? (cell movement)

cell crawling (towards food) and phagocytosis (consumes)

Movement of Amoeba

G-Actin —> F-Actin

1) expansion

2) movement

Why do they (Amoeba’s) move slow?

they can steer and change direction

How do chloroplasts circulate in plant cells?(Proteins required)

F-Actin and myosin motor proteins

How does myosin work?

Moves along actin filaments

(consumes ATP every step_

Is the cell moving itself?

no, things inside it are

Why does chloroplast circulate?

to perform photosynthesis (moves in 1 big circle)

How do transport vesicle move? (Proteins required)

Microtubules

Kinesin motor proteins

Dynein motor proteins

Kinesin motor proteins

positive end direction (away centrosome)

Dynein motor proteins

negative end direction (towards centrosome)

Golgi apparatus —> plasma membrane uses:

kinesin

How do sperm cells swim towards an egg? (Proteins required)

Microtubules
Dyneins

Eukaryotic flagella motion

Work by bending (not rotating)

What is required for MT to move? (flagella)

ATP —> shift

What happens if there is no plasma membrane surrounding the MT and Dyneins?

impair transport functions

Eukaryotic flagella structure

Microtubules and Dyneins wrapped in plasma membrane

Eukaryotic flagella location

inside plasma membrane

Sperm swimming good direction

straight line

Sperm swimming bad direction

tumble

Sperm swimming good direction (flagella)

bending even

Sperm swimming bad direction (flagella)

bending random

Sperm swimming sensing

thermotaxis (warmth) and chemotaxis (hormones)

thermotaxis (warmth)

chemotaxis (hormones)

How does an egg move towards sperm cells?(Proteins required)

Microtubules and Dyneins

Cilia structure

similar to flagella

Cilia composition

connected to EMC

Difference between cilia structure and flagella

cilia = shorter and more numerous

flagella = shorter and more numerous

Egg movement of cilia

rolls along the surface

Egg transport

ciliated cells in fallopian tube