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Ch 13 Motors
Molecular motors
37
Biology
Undergraduate 3
04/23/2012

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Term
Molecular motors are controlled by what filaments?
Definition
Intermediate filaments
Term
Acrylamide in your food?

“…acrylamide in food is formed when …___ reacts with certain naturally occurring sugars such as ____. This only happens when the temperature during cooking is sufficiently high, a temperature which varies depending on the properties of the product and the method of cooking…”
Definition
asparagine, glucose
Term
Myosin
Definition
Actin Positive
Term
Kinesins
Definition
Microtubule positive
Term
Dyenins
Definition
Microtubule negative.
Term
Motor heads
Definition
ATP hydrolysis
Binds to filament
Called motor domain
Term
Tails
Definition
Determines the cargo that is bound
Determines the biological function of motor
Term
Kinesins and myosins both
Definition
Structurally similar
Bind and hydrolyze ATP to facilitate movement
Changes in structure associated with ATP hydrolysis
This conformational change in structure results in movement
Term
Myosin II
Definition
Globular N-terminal head
Binds and hydrolyzes ATP to move along actin filaments
Walks to +
All but one of the myosin family of motors go to + end (VI)
Term
Kinesin
Definition
Globular head domains
Movement along microtubules toward + end
Humans have >40
Term
Myosin II think filaments

Myosins are bound together by their ____ into thick filaments

Thick filament is ____
No ______ between the two heads of the myosin
Myosin does not move processively, it only takes____ before letting go
Definition
tails, bipolar (motors face both ways), , coordination, one or a couple of steps
Term
Contraction
Definition
Brain sends signal
Motor neuron triggers an action potential at muscle cell membrane
Results in release of calcium from sarcoplasmic reticulum
Term
Myofibrils contain
Thin and thick filaments
Definition
Sarcomeres
partly overlap
Term
Thick filaments
Thin filaments
Definition
Myosin
actin
Term
What does calcium do?
Myofibril - made up of ____ - has ___
Actin has other molecules bound - _____
Resting state - ____ binds to ______ and pulls it out of the groove - inhibits binding to____ (thick filaments)
Calcium releases ...
Definition
sarcomere, actin
tropomyosin and troponin
troponin, tropomyosin
myosin II
tropomyosin from troponin
Term
Sliding filaments

Thick filament bipolar -_____ moves to _____ end of actin filament
Definition
myosin, positive
Term
Calcium release causes _____ and calcium ______ into the sarcoplasmic reticulum by _______ leads to ______ - both require a lot of ATP
Definition
contraction, reuptake, Calcium ATPase, relaxation
Term
How Myosin II works...
Definition
Myosin bound in non-nucleotide bound form (RIGOR)
ATP binding causes release of filament
Term
Hydrolysis to ______ associated with the myosin head moving forward
Definition
ADP + Pi
Term
Release of ___________; now the head snaps back to the original position - called the ______.
Definition
Pi and tight binding of myosin-ADP
POWER STROKE
Term
After the _____ (conformational change),
Definition
Power Stroke, ADP is released, returning the Myosin head back to original configuration.
Term
Kinesin motor movement
Start with...
ATP binding to forward head causes head to be ____ and also causes conformational change so that the other head ...
Definition
...one head bound and one head not bound.
...tightly bound (rigor) to microtubule
...swings past the ATP-bound head
Term
Note the difference - rigor is ATP-bound for____ as compared to non-nucleotide bound for_____
Definition
kinesin, myosin
Term
Kinesin motor movement continued...
______from the front head - now the non-nucleotide bound head binds to _____
And ATP is hydrolyzed (___________)
.... are coupled to create movement of arms
Definition
ADP is released, microtubule
back to the beginning
ATP hydrolysis and ATP binding
Term
The time that any given kinesin head is attached is ...

The time that any given myosin head is attached is...
Definition
half the time
very little of the time
Term
Kinesins v. Myosin

Kinesins move .... (this has to do with the fact that it is always bound by one or the other head)
Processivity allows ...from one place to another in cells - myosin never operates ...
Definition
...processively - meaning that travel for hundreds of cycles without dissociating
...very few motors to move organelles
...as a single molecule (always an array)
Term
Myosin v. Actin

Movement is based on ...
Speed is gained by ... kinesins
Definition
...attachment and rate of ATP hydrolysis
...myosin being in arrays compared to
Term
Kinesins function
Definition
Organelle placement (Golgi) (tug-of-war)
Mitotic and meiotic spindle formation and chromosome separation
Term
Kinesin Centripetal -
Kenesin Centrifugal -
Definition
toward middle or center
toward periphery
Term
Dyenin
Definition
Attachment to membranes mediated by large protein complexes
Term
Dynein/dynactin complex
Definition
Tails bind to receptors for motor proteins on organelles
Term
Two classes of Dyneins
Definition
Cytoplasmic
Ciliary or axonemal (cilia and flagella)
Term
Dyenins are what type of motors
Definition
Microtubule minus-end motors
Largest of motors and fastest
Term
Lysosome placement is dependent on ...
Definition
microtubules
Term
Alzheimer’s disease
______ disease
Characterized by ______ tangles and plaques
__________ - receptor for a motor protein (kinesin 1) in neurons
Defect in APP causes neurons to become clogged
Trafficking defect
Definition
Neurodegenerative
neurofibrillary
Amyloid precursor protein
Term
Regulation of motor proteins
Definition
Continuous tug of war on microtubules
Animals that can change color rapidly - response to hormone changes
Some pigment molecules transported on microtubules
Term
Phosphorylation of _____ light change releases from ______(____takes over)
Definition
kinesin, microtubule, dyenin
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