Lecture 11: Microtubule motor proteins Flashcards

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1
Q

What direction does kinesin move in?

A

Towards the plus end

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2
Q

What direction does dynein move in?

A

Towards the minus end

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3
Q

What is the main process of a microtubule motor protein moving?

A
  1. ATP hydrolysis loosens the attachment of head 1 to the microtubule
  2. ADP release and ATP binding changes the conformation of head 2
  3. This moves head 1 forwards
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4
Q

What are the two types of dynein?

A

Axonemal
Cytoplasmic

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5
Q

What is cytoplasmic dynein?

A

Works with its partner complex dynactin
Moves cargos by binding to adaptor proteins

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6
Q

What are the two roles of microtubule motors?

A

Facilitates membrane traffic by delivering vesicles
Position organelles into the cytoplasm

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7
Q

How do microtubules and motor proteins position organelles in the cytoplasm?

A

Cytoplasmic dynein moves the ER inwards slightly
Transports golgi apparatus towards the cell centre

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8
Q

What are the two types of sliding caused by motors?

A

Antiparallel sliding
Parallel sliding

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9
Q

What is antiparallel sliding?

A

Occurs in meiotic and mitotic spindles

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10
Q

What is parallel sliding?

A

Occurs in cilia and flagella

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11
Q

What are some examples of cells with flagella?

A

Vertebrate sperm
Protozoa

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12
Q

What are some examples of cells with cilia?

A

Protozoa
Epithelia

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13
Q

What are axonemes?

A

Specialised stable microtubule structures
Found in cilia and flagella

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14
Q

What is the role of axonemal dynein?

A

The dynein in axonemes
Drives ciliary and flagellar beating

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15
Q

What are myosins?

A

Actin based motor proteins

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16
Q

How do myosins move?

A

Move along actin filaments using energy from ATP hydrolysis

17
Q

What is myosin II?

A

Muscle myosin

18
Q

What is the structure of myosin II?

A

Long coiled tail that can assemble into filaments

19
Q

What are some diseases caused my desmin mutations?

A

Muscular dystrophy
Cardiac myopathy

20
Q

What is the role of desmin intermediate filaments?

A

Form a scaffold that stabilises the muscle Z discs
Maintain organisation in the cell Connect to cell-cell junctions

21
Q

What is the myosin II cross bridge cycle?

A
  1. Attached
  2. Released
  3. Cocked
  4. Force-generating
22
Q

What is the role of myosin I?

A

Short distance organelle movement
Helps reshape plasma membrane on the underlying actin filaments