2.17.2010 – Cytoskeleton<br />Continuation of cellular respiration<br />
Diseases Associated with Mutations in cellular Respiration
Leigh Syndrome – decreased activity in cytochrome c oxidase
Brain tissue loss and muscular deficiency
Complex II deficiency
Short stature, seizures, mild swelling in and around the brain, encephalopathy
Lack of thiamine, vitamin B1
Decreased activity in pyruvate dehydrogenase and alpha-ketogluterate dehydrogenase (regulatory enzyme in krebs cycle)
Can take thiamine supplements
w/out B1, krebs cycle can work as well
nervous system disorders.
The cytoskeleton regulates
cell motility (entire cell)
Motility and trafficking of proteins, organelles, RNA in the cell
Counterparts in Bacteria – slide 2
Microtubules (formed by dimmers of the tubulin monomers) – counterpart in bacteria, FtsZ gene
Actin (microfilaments) – counterpart in bacteria, MreB
Intermediate Filaments – counterpart in bacteria Crescentin
Properties of Microtubules, Microfilaments, and Intermediate Filaments
Growing and shrinking end
Formed by the dimer tubulin monomer
Organized into structure that allows for a specific motility
Whip-like movement such as sperm cells.
Make up much of the cytoplasm to make a dense environment
Actin is smallest
Link g-actin together non-covalently
Cytosol of an amoeba is a gel, or plasma gel. The gel is converted to plasmasol, so it’s more fluid and the movement is more fluid
If you have a structure like an amoeba, the cytosol is more gel like than water, so plasma gel. For movement, the gel is converted to plasmasol, so it’s more fluid and the movement is more fluid, which tends to create a force or pressure along membrane as force is mediated
Intermediate Filaments – structure and support for cells
No polar sides! So very good at structural support system for cells.
Just on the inside of nuclear envelope
Strengthening of nerve cells
Desmin helps maintain muscle cell shape when undergoing mechanical movement
Not as dynamic as microfilaments and microtubules
Cytoplasmic filament (slide 3) have concentrated areas in sites called desmosomes, which provide linkage between cells to hold them. Proteins make desmosomes, but the filaments hold the cells together by interacting with desmosomes. They don’t hold directly to cells, but link to one another to hold cells together in a tissue structure.
Nuclear lamins (blue area around nucleus)
Can help regulate what goes in and out of nucleus
(Slide 4) 8-12nm. Begins with assembly of alpha helix monomer, made of four alpha helices with 3 regions that separate the monomer itself. 310-318 amino acids, all of which are hydrophilic. At the end, amino and carboxy terminus, hydrophobic, tend to be regions that associate with other types of proteins.
Coiled-coil dimers come together in a staggered position for amino and carboxy terminus do not overlap, and this allows the tetramers to pack together at the heads, through non-covalent bonding. Eight tetramers are brought together and form a rope-like structure.
Classes of Intermediate Filaments
Specificity of intermediate filaments can help us identify cells and localize the filaments in the cell.
Slide 6 is trying to show intermediate filaments at the desmosomes
Epidermolysis bullosa simplex
K14 gene generates two types of Keratin, class I and II.
Any amount of stretching will rip epithelial cells apart and can lead to blistering.
Epidermalisis – lysing of the epidermis below cymplex
Mutation in keratin – k14 gene – that is responsible for generating two classes of keratin, I and II, when they can’t function they can’t hold selves together, so blistering wounds can be found on the skin.