Cell Motility

Question 1

What are cilia and flagella built from?

Answer 1

Microtubules - dynein??

Question 2

What is the major functional structure in cilia and flagella?

Answer 2

The axoneme

Question 3

The bending of what structure in cilia and flagella results in their movement?

Answer 3

The axoneme

Question 4

Structure of axoneme

Answer 4

9 outer pairs, pair in centre. Radial spokes

Question 5

Structure of basal bodies

Answer 5

9 triplet microtubule array, derived from centriole

Question 6

What are the outer doublets of the axoneme made up of?

Answer 6

Complete (A) fibres and incomplete (B) fibres

Question 7

Which motor protein is present on the outer doublets?

Answer 7

Dynein

Question 8

What do dynein arms do?

Answer 8

Generate flexion when dynein hydrolyses ATP and changes shape

Question 9

In isolation, what does dynein produce?

Answer 9

Microtubule sliding but in flagellum causes bending

Question 10

Why does dyneim cause microtubule bending in flagellum?

Answer 10

Due to linking proteins in flagellum

Question 11

What does the inner dynein arm affect?

Answer 11

Shape of wave

Question 12

What does the outer dynein arm affect?

Answer 12

Power

Question 13

What do basal bodies do?

Answer 13

Act to firmly root cilia at cell surface

Question 14

What are the 2 types of actin-based movement?

Answer 14

1. Muscle movement - moves whole organism

2. Non-muscle movement - moves individual cells

Question 15

What is the contractile unit of muscles? How do they influence the appearance of skeletal muscle?

Answer 15

• Sarcomere - Give skeletal muscles their striated appearance

Question 16

What are filopodia?

Answer 16

One-dimensional extensions containing a core of long. bundled actin filaments. Protrude first

Question 17

What are lamellipodia?

Answer 17

Two-dimensional extensions contain cross-linked mesh of actin filaments. (broad extensions)

Question 18

What is ‘Gel-sol transition’ in the movement of Amoeboid? How does this allow movement?

Answer 18

• Transition from gel-like cytoplasm (outer region) to liquid-like cytoplasm (inner region)
• Actin underlying cell membrane has weak point allowing membrane protrusion and extension

Question 19

What is the name of the transition found in Amoeboid movement?

Answer 19

“Gel-Sol” transition