Eukaryotes: Cytoskeleton and Cell movements

Eukaryotes

• Provides cell shape

• allows movement of cell content during replication

• allow movements during regular physiological processes

• propels cell and its surroundings

Prokaryotes

• Provides cell shape

• allows movement of cell content during replication

Microtubules

Largest of the 3

• Polar

• Made from globular monomers

• Strict and provide compression strenght

• moves cell content and the cell itself

Make a tube created from heterodimer made from tubulin.

• one end is larger than the other and can grow/shrink very fast

Motor proteins

Can utilize microtubules as transport tracks

• dyneins and kinesins

Dyneins - go to negative direction

kinesins - go to positive direction

both carry a vessicle on top to transfer materials

Cilia

Made of microtubules

• basal body is made of 9 triplets

• motile body is made of 9 doublets + 2 central bodies

  • nonmotile primary cilia are made of 9 doubles, 0 centers

allows movement of cell by moving asymmetrically

Flagella

moved by dyneins who allow 9 degrees of freedom

• slides proteins forwards

Allow movement of cell by moving side to side

sperm and egg

sperm is motile since it can move on its own, the egg is not motile but it is mobile.

• egg is part of the environment

  • cilia move environment

microtubules organizing center

centrosomes function as motile

• negative ends can embed themselves inside

  • guides structure during cellular division

spindle apparatus

made of microtubules

microfilaments

• made of globular proteins

• polar

• Actin

• polymerizes into Factin for filaments

• Shapes cells and provides movements

  • provides tensile strength

polymerization of f-actin involves using ATP, releasing ADP + P

cells with outward membranes

actin supports cells with outward membranes

• supports microvill in intestinal cells (outfolds of plasma membrane)

actin-myosin

works for muscle contractions

involves thick myosin heads pulling on actin filaments

Pseudopodium

• arm like projections whcih eukaryotes can shoot to crawl or move

• allows it to decide/feel where it is going

  • supported by actin and myosin filaments

Cellular streaming

when cytoplasmic content is moving in plants

alternative names: cytoplasmic streaming

caused by actin/myosin

bacteria hijack

cytoskeleton can be hijacked by bacteria to find other bacteria

• gram negative bacteria can hijakc skeleton of neutrophil to find other neutrophil

Intermediate filament

• apolar

• made of filamentous monomers

• provides high tensile strength

• animal only structure

• coils from an N-head to C-tail

  • forms tetrameters to stack on top of each other

desmosomes

example of IF prtoeins + keratin

• intracellular keratin projects to inside of cells

• hair is keratin

  • keratin is a type of IF

Extracellular kertin

forms claws, hair, nails, feathers, beaks

• veery strong

nucleur lamin

• inner lamin of nucleus is made of IF

• nucleus sits in a layer of IF