Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
23 Cards in this Set
- Front
- Back
|
focal adhesions
|
dynamic structures where the membrane binds to the surface
|
|
|
where are stress fibers located, and what are they
|
located Just beneath the plasma membrane at the focal adhesions...
stress fibers are linear arrays of actin and myosin II filaments, linked by actin-associated proteins |
|
|
what allows the stress fiber to contract when the myosin is activated
|
The antiparallel (tail-to-tail) arrangement of the myosin molecules in the myosin filaments
|
|
|
what does The tension generated in the stress fibers do
|
stengthens the “grip” of the cell onto the surface
|
|
|
explain in detail how Fibroblast locomotion works
|
1st the lamellipodium receives a chemical signal
Reception of a chemical signal molecules by a receptor protein in the plasma membrane of the leading edge of the cell triggers the assembly of an actin cytoskeleton via the Arp2/3 protein complex. The assembly of the actin network at the leading edge of the lamellipodium pushes against the plasma membrane and extends it forward New focal adhesions are made onto the underlying surface in the new areas over which the plasma membrane extends At the same time the actin network at the trailing edge of the lamellipodium is disassembled, retracting the cytoplasm at the trailing edge of the lamelllipodium, allowing the lamellipodium to move forward –a form of actin filament “treadmilling”. |
|
|
cytoplasmic streaming
|
flow of cytoplasm towards the lamellipodium during fibroblast locomotion
|
|
|
very generally, how are tissues formed?
|
-cells are bound together by specialized junctional proteins
-Cells are imbedded in the fiber-filled extracellular matrix -Cells adhere to non-cellular substrata like basement membranes |
|
|
what is the glycolax
|
an extension of the plasma membrane Immediately surrounding the cell
|
|
|
The glycocalyx is formed from
|
the carbohydrate chains of integral membrane glycoproteins and some secreted proteins that are entangled in the carbohydrate chains
|
|
|
what is the function of the extracellular matrix
|
The ECM plays a key role in determining the shape of the cell
Plays a role in determining cellular activity –in regulating the secretory activities of cells, for instance. |
|
|
give an example of an extracellular matrix
|
basement membrane
|
|
|
locations of basement membrane
|
Underlies the basal surface of epithelial cells that comprise the epidermis of the skin and the lining of the gut and respiratory tracts, and blood vessels
|
|
|
what does the basement membrane do?
|
Provides:
mechanical support: a substratum for cell migration separates the epithelium from deeper tissue layers Acts as a barrier to the passage of macromolecules (e.g. lining of blood vessels in kidneys prevents proteins from filtering out into the urine) |
|
|
What is the extracellular matrix composed of
|
1) Fibrous proteins –collagens
2) Proteoglycans 3) Fibronectins 4) laminins |
|
|
what is Collagen
|
A family of fibrous glycoproteins with members found throughout the animal kingdom
|
|
|
what produces collagen
|
fibroblasts, smooth muscle cells, and epithelial cells
|
|
|
describe the structure of collagen
|
Trimeric –3 alpha-helical polypeptide chains, wrapped around each other to form a triple helix.
For some types of collagen, the trimeric chains can assemble side-by-side into rigid cable-like fibrils |
|
|
what are the fibrils of collagen strengthened by
|
covalent cross-links
|
|
|
Function of collagen
|
Collagen provides the insoluble framework of the ECM and therefore of connective tissues
E.g. collagen properties provide the mechanical strength of tendons that link muscle and bone -resistance to stretching Other types of collagen provide the transparent layers of the cornea in the eye. |
|
|
what is a Proteoglycan
|
Core protein molecule to which chains of carbohydrates -glycosaminoglycans (GAG’s) are attached
|
|
|
what is special about the carbohydrate chains in proteoglycans
|
The carbohydrate chains are sulfated –have a negative charge and so bind huge numbers of cations which in turn attract large numbers of water molecules (hydration shell)
Makes a soggy (hydrated) gel that fills the ECM between collagen fibers and resists compression forces. |
|
|
what is the structure of a Fibronectin
|
Two similar polypeptide chains linked by disulfide bridges.
Each polypeptide consists of a string of 30 or more modular domains, which are grouped to form functionally distinct units which bind other proteins in the ECM and cells. |
|
|
whats so special about fibronectins?
|
Fibronectins can bind tightly to receptor proteins on the surface of cells
Each fibronectin type may therefore play a role in guiding cells through the ECM during development and in binding cells to substrata like the basement membrane |
