6.6 Bio 107 Cytoskeleton
What are the 2 structures that make up centrosomes?
2 centrioles (microtubules) which are perpendicular to each other.
How big are microfilaments?
7nm in diameter, 1-2 microns in length.
How big are intermediate filaments?
8-12 nm. In the middle.
What is the structure of a centriole?
9 triplets of microtubules arranged in a ring.
The centriole in a basal body has what numerical structure?
9 triplets of microtubules, one central microtubule
What is the numerical structure of microtubules in cila and flagella?
9+2. 9 outer microtubule doublet. Motor protein/dyneins connecting the doublets. 2 central microtubules. Radial spokes connecting the central microtubules to the doublets. Cross-linking proteins between outer doublets.
What do Amoeboid cell movement require?
Actin filaments.
How do Cila move?
Back and forth sweeping motion
What helps distribute cell components in plant cells?
Cytoplasmic streaming
What does polarity have to do with microtubules?
Microtubules assemble with polarity. The Beta/+ end grows and shrinks faster.
What are the molecular structures of the cytoskeleton?
Microtubules, microfilaments, intermediate filaments.
Explain how motor proteins and microtubules work together.
Motor proteins "walk" vesicles along cytoskeletal fibers using the energy of ATP.
How do muscles use microfilaments?
Muscle cellls contain long chains of microfilaments and myosin filament arrays which contract together, allowing movements.
Are intermediate filaments found in plant cells?
No.
What is strange about centrioles?
Probably don't have a function but are essential for the formation of cilia and flagella.
Concept 6.6
The cytoskeleton is a network of fibers that organizes structures and activities in the cell.
Are centrosomes found in animals? In plants?
Yes, No.
What makes up the cytoskeleton?
a network of polymers
What are microfilaments made of, and what is the structure?
actin monomers in a double twisted strand.
What is cytoplasmic streaming driven by?
actin/myosin and gel/sol transitions.
What are microtubules made of?
alpha and beta tubulin dimers assembled in a coil forming a hollow tube.
What does the basal body in a cilia or flagella do?
anchors the cilium or flagellum
What are the shared structure of cila and flagella?
core of microtubules in a circle, basal body, motor protein called dynein.
What does dynein do for cilia or flagella?
drives the bending movements
What are intermediate filaments?
fibers with diameters in a middle range. Part of the cytoskeleton, strongest at bearing weight.
What is the funtion of microfilaments?
forms support of cell shape, tension bearing protrusions, required for cell division, movement, muscle contraction, cytoplasmic streaming.
How are microtubules arranged in cilia and flagella?
in a circle.
What is the function of the cytoskeleton?
it organizes the cell's structures and activities, anchoring many organelles.
What are examples of the many protein types of intermediate filaments?
keratins, desmins, etc. tissue specific.
What is the structure of intermediate filaments?
like a rope
What are cilia and flagella?
microtubule-contraining extensions
What is an example of microfilaments?
microvilli on intestinal cells are supported by tightly packed actin filaments.
What is the substrate of microtubules?
motor proteins (myosin)
What is a downfall of mutation in intermediate filaments?
mutations produce many diseases.
What is the substrate of microfilaments?
myosin motors
What is the function of microtubules?
organizes and supports movement of organelles and chromosomes, supports movement in cilia.
How do flagella move?
snakelike S shape
What is the funtion and advantage of intermediate filaments?
support cell shape and fix organelles in place, and they are stronger and more stable than actin or microfilaments.
Where do microtubules start growing from?
the centrosome.
What is a microtubule?
the thickest of the three components of the cytoskeleton.
What are microfilaments?
the thinnest molecular structure of the cytoskeleton. Also called actin filaments.
What is different between cilia and flagella?
the way they move.
