Cilia, Flagella, and Motor Proteins

What are Cilia?

A cilium is an organelle found in eukaryotic cells. Cilia are slender protuberances that project from the much larger cell body.

What are thick filaments?

A collection of myosin that have myosin heads at either end.

What are Flagella?

A flagellum is a lash-like appendage that protrudes from the cell body of certain prokaryotic and eukaryotic cells. The word flagellum in Latin means whip.

What is the simple integrated theory of eukaryotic evolution?

An early archaea developed an effective locomotive system and the ability to endocytose, thereby becoming an effective predator.

Attachment

Attach to exterior surface via adhesive junctions and integrin's.

What kind of structures are Cilia and Flagellum?

Axonemal Structures

How do the flagellum of bacteria differ from the flagellum of an animal cell?

Bacteria flagella are extracellular and are driven by rotary motion. This is similar to ATP synthase in Mitochondria and Chloroplasts.

What does Ca2+ bind?

Binds troponin C and causes a structural shift that moves tropomyosin out of the way.

Actomyosin complexes allow...?

Cells to move along a surface.

How does amoeboid movement work?

F-actin --> G-actin in the REA, G-actin flows to the front, G-actin and F-actin are now in front, pulls the cell forward.

What types of actin does amoeboid movement use?

F-actin and G-actin

What are two structures used in cell crawling?

Filopodia and Lamellipodia

What are Non-Motile Cilia or Primary Cilia?

In comparison to motile cilia, non-motile (or primary) cilia usually occur one per cell; nearly all mammalian cells have a single non-motile primary cilium. In addition, examples of specialized primary cilia can be found in human sensory organs such as the eye and the nose.

What is Tropomyosin?

Interferes with the myosin heads contacting the filament.

What are Motile Cilia?

Larger eukaryotes, such as mammals, have motile cilia. Motile cilia are usually present on a cell's surface in large numbers and beat in coordinated waves.

What is a nuclear piston?

Lobopodia (Blebs) fire the nucleus forward forcing the cytoplasm and the entire cell in that direction using actin/myosin complexes.

What are thin filaments?

Microfilaments - actin

Protrusion

Microfilaments grow in a certain direction and push the plasma membrane out in that direction.

Translocation

Microfilaments grow with supporters to push cells in a given direction.

How is Myosin used on Microfilaments?

Myosin's use ATP to pull on the microfilaments.

Are Cilia and Flagellum extracellular structures?

No, they are protrusions of the cellular membrane

How does a cell crawl?

Protrusion, Attachment, and Translocation

What is the sequence of Myosin Action?

Reach, Grab, Pull, Release --> 1 ATP per cycle

What are Axonemal structures?

Serves as the "skeleton" of these organelles, both giving support to the structure and, in some cases, causing it to bend.

Microtubules and Dyneins in Axonemes

They double on the edge, they do not have a MTOC and are very stable structures.