unit 6 - cytoskeleton Flashcards
cytoskeleton is found in
only eukaryotic cells, almost always animal cells
three components of cytoskeleton
actin filaments (diameter ~6 nm), intermediate filaments (diameter ~12 nm), microtubules (diameter ~24 nm)
major classes of intermediate filaments
- keratin filaments in epithelial cells. most abundance type of intermediate filament
- vimentin and related filaments in connective tissue, muscle cells, and glial cells of nervous system
- neurofilaments in nerve cells
- nuclear lamins under the nuclear envelope of all animal cells, provides struture
functions of intermediate filaments
intermediate filiments composition
rope-like, made of coiled-coiled tetramers
thousands of protein subunits assembled into threads
great tensile strength
abundant in epidermal/skin cells to allow them to stretch without breaking
Epidermolysis bullosa
genetic disease of intermediate filaments. mutations in keratin genes. layers of epidermal cells not joined together well, skin is extremely prone to mechanical damage. severe blisters as the skin shears off
nuclear lamins
inside
- disassemble via phosphorylation in each cell division, reassemble via in each daughter cell