BIO 311C TEST 2 QUESTIONS AND ANSWERS A+ GRADED
Cytoskeleton
and three moelcular structure
The cytoskeleton is a network of fibers extending throughout the cytoplasm
It organizes the cell's structures and activities, anchoring many organelles
It is composed of three types of molecular structures:
Microtubules
Microfilaments
Intermediate filaments
The cytoskeleton transmits signals from the plasma membrane throughout the cell.
The cytoskeleton helps to support the cell and maintain its shape
Interacts with motor proteins
Inside the cell, vesicles can travel along "monorails" provided by the cytoskeleton
Recent evidence suggests that the cytoskeleton may help regulate biochemical
activities
Motor Proteins
o produce motility
o Motor proteins cause cilia and flagella to bend by pulling on cytoskeleton fibers.
Microtubules
-structure
-diameter
-protein subunits
-main factors
the thickest of the three components of the cytoskeleton. Composed of tubulin
Structure: hollow tubes, walls consist of 13 columns of tubulin molecules
-Each tubulin protein is a dimer of alpha and beta subunits that can add or subtract from
a growing filament tube
-One end of the filament (called the plus end) assembles and disassembles much more
quickly than the other end
Diameter: 25 nm with 15 nm lumen
Protein subunits: tubulin
Main factors: maintenance of cell shape, cell motility, chromosome movements in cell
division, organelle movements
, Microfilaments
-structure
-diameter
-protein subunits
-main factors
also called actin filaments, are the thinnest components
Structure: two intertwined stands of actin
Diameter: 7nm
Protein subunits: actin
Main functions: maintenance of cell shape, changes in cell shape, muscle contraction,
cytoplasmic streaming, cell motility, cell division
Intermediate filaments
-structure
-diameter
-protein subunits
-main factors
fibers with diameters in a middle range
Structure: fibrous proteins supercoiled into thicker cables
Diameter: 8-12 nm
Protein subunits: one of several different proteins of the keratin family
Main functions: maintenance of cell shape, anchorage of nucleus and other organelles,
formation of nuclear lamina
Microtubules
-Centrosome
-Cilia and Flagella
Microtubules grow out from a centrosome near nucleus
"microtubule-organizing center"
the centrosome has a pair of centrioles, each with nine triplets of microtubules arranged
in a ring
an area near the nucleus considered the microtubule organizing center.
Centrioles
-Within each centrosome are a pair of centrioles
-Each composed of 9 sets of triplet microtubules arranged in a ring.
Cytoskeleton
and three moelcular structure
The cytoskeleton is a network of fibers extending throughout the cytoplasm
It organizes the cell's structures and activities, anchoring many organelles
It is composed of three types of molecular structures:
Microtubules
Microfilaments
Intermediate filaments
The cytoskeleton transmits signals from the plasma membrane throughout the cell.
The cytoskeleton helps to support the cell and maintain its shape
Interacts with motor proteins
Inside the cell, vesicles can travel along "monorails" provided by the cytoskeleton
Recent evidence suggests that the cytoskeleton may help regulate biochemical
activities
Motor Proteins
o produce motility
o Motor proteins cause cilia and flagella to bend by pulling on cytoskeleton fibers.
Microtubules
-structure
-diameter
-protein subunits
-main factors
the thickest of the three components of the cytoskeleton. Composed of tubulin
Structure: hollow tubes, walls consist of 13 columns of tubulin molecules
-Each tubulin protein is a dimer of alpha and beta subunits that can add or subtract from
a growing filament tube
-One end of the filament (called the plus end) assembles and disassembles much more
quickly than the other end
Diameter: 25 nm with 15 nm lumen
Protein subunits: tubulin
Main factors: maintenance of cell shape, cell motility, chromosome movements in cell
division, organelle movements
, Microfilaments
-structure
-diameter
-protein subunits
-main factors
also called actin filaments, are the thinnest components
Structure: two intertwined stands of actin
Diameter: 7nm
Protein subunits: actin
Main functions: maintenance of cell shape, changes in cell shape, muscle contraction,
cytoplasmic streaming, cell motility, cell division
Intermediate filaments
-structure
-diameter
-protein subunits
-main factors
fibers with diameters in a middle range
Structure: fibrous proteins supercoiled into thicker cables
Diameter: 8-12 nm
Protein subunits: one of several different proteins of the keratin family
Main functions: maintenance of cell shape, anchorage of nucleus and other organelles,
formation of nuclear lamina
Microtubules
-Centrosome
-Cilia and Flagella
Microtubules grow out from a centrosome near nucleus
"microtubule-organizing center"
the centrosome has a pair of centrioles, each with nine triplets of microtubules arranged
in a ring
an area near the nucleus considered the microtubule organizing center.
Centrioles
-Within each centrosome are a pair of centrioles
-Each composed of 9 sets of triplet microtubules arranged in a ring.
