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brendanbui
on FreezingBlue Flashcards.
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Does the cytoskeleton move around?
yes, it moves in order to alter the cell's shape, move materials from place to place, and move the entire structure
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What are actin filaments (microfilaments)?
- smallest diameter
- made of actin
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How do actin filaments form?
individual actin molecules polymerize and coil around each other
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Why do actin filaments have a distinct polarity?
- the strand is asymmetrical
- the two ends are different and are labeled as plus and minus ends
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What is treadmilling?
when filaments grow and shrink as actin subunits are added or removed from each end of the structure
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What else does actin filaments interact with during movement?
myosin
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What is myosin?
a motor protein that converts ATP into mechanical energy
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What makes the head of the myosin molecule bind to the actin and making it move?
the ATP binds to the myosin and then is hydrolyzed into ADP
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What is cell crawling?
directional extension of actin filaments pushes the plasma membrane into bulges called "pseudopodia" (false-feet)
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What is cytokinesis?
- cell division in animals
- actin filaments are arranged in a circle and must slide past each other, pinching the cell in two
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What is cytoplasmic streaming?
directed flow of cytosol and organelles around plant and fungal cells
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Intermediate filaments
- defined by size
- can consist of different proteins
- each end is identical
- purely structural role
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Keratin
- makes up the skin
- type of intermediate filaments
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Nuclear lamins
- dense mesh under nuclear envelope
- type of intermediate filaments
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microtubules
- alpha and beta tubulin
- largest cytoskeletal components (diameter)
- each end of microtubule has different polarity
- grow from a microtubule organizing center
- help with structure and movement
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centrosome
microtubule organizing center in animals
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centriole
- 2 bundles of microtubules within centrosome
- not needed for microtubule formation (scientists still not sure why they exist o.O)
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function of vesicles
transport material within cells
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vesicles travel along ___
- microtubule "rail road" tracks
- movement continued as long as ATP was available
- microtubules necessary for transport
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kinesin
- motor protein that controls movement of vesicles
- similar to a delivery truck that carries transport vesicles along microtubule tracks
- "walks" down the microtubule
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Bacterial flagella
- comprised of protein called flagellin
- rotate flagella like propeller
- not surrounded by membrane
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Eukaryote flagella
- comprised of microtubules
- whip back and forth
- surrounded by plasma membrane
- 9+2 arrangement
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basal body
- location where axoneme attaches to cell
- important for growth of axoneme
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axoneme
- 9+2 structure of microtubules
- isolated structure
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Who is Gibbons?
- studied cilia
- movement doesn't occur unless ATP is available
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dynein
- a large, motor protein that makes up the arms of the axonemes
- when ATP attaches to dynein, the end changes shape and the dynein walks up the microtubule
- causes the flagellum to bend back and forth
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