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Final Exam Pt 4

Many molecular motors are members of the _____ family P-loop NTPase
The first kinesin discovered was called _____ conventional kinesin
In kinesin, a _____ undergoes conformational change after nucleotide binding neck linker
The functional unit in a muscle cell is a sarcomere
_____ is the name given to actin monomers G-actin
_____ is a prokaryotic homolog of actin MreB
An ____ is a bundle of nine microtubule pairs surrounding two singlet microtubules. axoneme
A prokaryotic protein similar to tubulin is called a ____ FtsZ
Flagella are used for ____ in bacteria. chemotaxis
Molecules such as glucose that attract bacteria are termed ____ Chemoatractants
Myosin light chains are related to the ____ family of proteins. EF hand
A helical section that moves dramatically when NTP is bound is called the ____ in P-loop NTPases. lever arm
Troponin reacts in response to the ion ____ calcium
During a muscle contraction, the thin filaments (actin, tropomyosin, troponin) slide along the ______ thick filaments
Single molecules of myosin in actions were studied using ____ an optical trap
Actin likely evolved from a protein that bound ______ ATP
Microtulules are tracks for kinesins and _____ dyneins
Taxol inhibits the proliferation of cells by stabilizing the polymer form of ____ microtubules
Bacterial flagella are polymers composed of 53-kd subunits of a protein called _____ flagellin
Bacterial flagella rotate in one direction for smooth swimming and in the other direction to cause ____ tumbling
Energy used to propel molecular motors includes ATP, ion gradients
The major family(ies) of eukaryotic motor proteins is(are) myosins, kinesins, dyneins
The structure of dynein lends itself to the formation of oligomers
Binding of ATP causes ____ in myosin head affinity for actin filaments a decrease
Binding of ATP causes _____ in kinesin affinity for microtubules. an increase
Actin polymers will assemble automatically by self-assembly
How is MreB similar to actin? It folds into a similar tertiary structure, and Like F actin, it forms polymers.
What is the rate and distance of the movement of myosin heads? Each head moves 5 times per second, approximately 110 Angstroms
How does the length of the lever arm affect the rate? A mutated shorter arm has a reduced rate, and a mutated longer arm has a faster rate
Human spastic paraplegia has been linked to a mutation in kinesin family genes
Bacterial motors differe from eukaryotic ones in that the bacterial motor spins around a central axis
What is the energy source used to rotate the flagella? proton gradient
The structure in bacteria that rotates is referred to as the MS ring
The biased random walk motion of bacteria is the result of swimming with more tumbling when moving away from a chemorepellant
Molecules that cause bacteria to swim away from toxic substances are chemorepellants
How do molecular motors work? Proteins undergo conformational changes, in very small increments, which are converted to motor type activity
To what families are myosin, kinesin, and dynein related (in humans)? While amino acid sequences are varied, the 3-dimensional structures of myosin & kinesin are similar to the P-loop NTPase domains that r observed in G proteins. Dynein contains domains structurally similar to the P-loop NTPase domains in the AAA subfamily
Briefly describe the structure of myosin Myosin consists of a long stalk-like region with two heads at one end. The ATP-binding domains are near the heads, and the long stalk serves as an attachment site to other proteins
What serves as the track for myosin? Actin, in a polymeric form, serves as the molecular track for myosin
What is F-actin? The filamentous form of actin is a helical structure formed from actin monomers. It resembles a two-stranded string or cable. One end contains a "point" and the other end is "barbed"
What was learned using the optical trap laser studies? The Studies indicated myosin heads undergo structural changes in conformation when they bind to actin that pulls the actin filament, leading to a displacement of the beads.After a time period, the actin is released& rturns to orig position between 2 beads
Describe the experiment that supports role of the lever arm in myosin motor activity Investigators deleted sequences to shorten the lever arm & inserted sequences to extend the lever arm. The rate of myosin movement along an active filament decreased as the lever arm was shortened & increased as the lever arm was extended
What is the cause of Charcot-Marie-tooth disease? This neuropathy is caused by a mutation in kinesin type K1F1B~B
How does the action of kinesin differ from that of myosin on its track? Myosin binds and releases actin after each stroke. In contrast, kinesin is a processive enzyme. The heads operate in concert, with one, then the other binding.
Compare the speed of movement of a motile bacterium to a human the bacterium can move approximately 25 um/sec or about 10 body lengths. To achieve this a human would have to run a 100-m dash in 5 sec.
How is a bacterial motor similar to ATP synthase? In both cases, a proton moving across a membrane into a channel causes a structure to rotate.
How are flagellin subunits arranged in the bacterial flagellum? Flagellin subunits form helical polymers containing 5.5 subunits/turn. The subunits are arranged around a hollow core and can extend up to 15 um in length
Is the motion of a bacteria deliberate and exact toward a target chemoattractant, or is it random? While the bacteria will eventually arrive at its source, there is a great deal of random movement caused by the tumbling as it seeks the proper direction
Created by: AshCha