Cytoskeleton Flashcards
(21 cards)
What is the cytoskeleton?
The cytoskeleton is a network of filaments and tubules that extends throughout a cell, through the cytoplasm, which is all of the material within a cell except for the nucleus.
What is the function of the cytoskeleton?
Structural framework Stabilize the tissue Keeps the components in place Pseudopodia formation Mitotic spindles Cytokinesis Formation of microvilli, cilia, and flagella
What are Microfilaments?
Microfilaments, also called actin filaments, are polymers of the protein actin that are part of a cell’s cytoskeleton.
What is the role of globular actin or G-actin?
Helps in enzymatic reactions
What is the role of filamentous actin or F-actin?
Helps in muscle contraction
What are some characteristics of microfilaments?
They are flexible than microtubules
Abundant in the region beneath the cell membrane
What is the function of microfilaments?
They ANCHOR intrinsic proteins of the cell membrane
They help in cellular locomotion by pseudopodia formation
They form structural core of microvilli
What are intermediate filaments?
Two long chains of protein that have an N-terminal and a C-Terminal.
How many types of IF are there?
Keratin Desmin Vimentin Neurofilaments Glial filaments Lamin
Characteristics of Keratin filaments?
In the epithelial cells of the skin as Tonofibrils (bundle of keratin filaments)
And they terminate on desmosomes
Where are Vimentin filaments located?
Fibroblasts
Macrophages
Endothelium
Where are desmin filaments found?
Z discs of the muscles
Where are neurofilaments found?
Neurons
Where are Glial filaments located?
Astrocytes as Glial Fibrillary Acid Protein
Where are Lamin filaments?
Nuclear lamina (support the nuclear envelope)
What are Microtubules?
They are made out of subunits called tubulin. Each tubulin subunit is made up of one alpha and one beta-tubulin that are attached to each other.
They make a tube-like structure.
What is the function of Intermediate filaments?
They connect the nuclear membrane to the cell membrane.
They form flexible scaffolding for the cell & help it resist
external pressure.
In their absence, cell rupture more easily.
What are the characteristics of microtubules?
They are polymers of tubulin which takes place in the centrosome. This polymerization requires Mg++ and GTP. The minus ends of microtubules are anchored in structures called microtubule organizing centers (MTOCs) and the plus end is the growing end.
What do Microtubule-associated proteins (MAPs) do?
MAP prevents depolymerization of the microtubule
MAP assists in the intracellular movement of organelles by using ATP
What are the functions of Microtubules?
- They provide the tracks along which different
molecular motors move vesicles & organelles from one
part of the cell to another. - They also form spindle, which moves chromosomes in
mitosis. - They are present in the flagella of sperm and cilia to
provide locomotion of these structures.
What are the examples of molecular motors?
Kinesin (Towards the +ve end)
Dynein (Towards the -ve end)
