Tissue Architecture Flashcards
What are the cytoskeleton functions at a tissue level?
Muscle movement
What are the cytoskeleton functions at a cellular level?
Cell morphology, motility, cell adhesion and division
What are the cytoskeleton functions at a subcellular level?
Organization, tensile strength, chromosome segregation, cell polarity and vesicular movement
How are cytoskeleton filaments adaptable?
They begin as small soluble subunits that, when signaled will form large filamentous polymers
How do cytoskeleton elements stabilize?
They are generally thermally unstable but when they group together and stagger they gain strength and develop rope like properties
What is the function of intermediate filaments and where are they found?
They provide tensile strength to the cell able to withstand mechanical forces. They are generally found in cytoplasm, anchored to plasma membrane.
How are intermediate filaments formed?
alpha helical monomers coil to form a dimer. Two dimers will stagger eachother formed a tetramer. Tetramers will then form a lateral association to give rope like properties.
What happens when intermediate filaments are mutated?
Can cause blistering and has been linked to progeria when nuclear lamina is disrupted
What is the function of microtubules and where are they found?
They are used in cell organization and movement of vesicles/organelles. They are used in mitotic spindles, cilia/flagella.
How are microtubules formed?
alpha and beta tubulin forms a heterodimer that line up and form a protofilament that have a plus and a minus end. These filaments form a tube that can rapidly assemble and disassemble
What is the role of gamma tubulin?
They act as anchor units in the formation of microtubules that polymers can grow out from.
What is taxol?
a drug that binds and stabilizes microtubules. This can result in a stoppage of cell cycle since spindles will not function
What is the function of microfilaments and where are they found?
Present in all cell types and they are used for locomotion, phagocytosis, cell division and contraction
How are microfilaments formed?
Actin filaments are twisted polymers of G-actin that have structural polarity like microtubules.
What is phalloidin?
a drug that binds and stabilizes filaments which can result in a stoppage of cell function
How do proteins modify actin function?
They provide stability to the structure since it is highly unstable. They can be used to stabilize, strengthen, cross-link or organize
What is the extracellular matrix/basal lamina and where is it found?
It is interlocking fibrous proteins and proteoglycans that are secreted by the cell then secreted out to aggregate. They interact with cells via transmembrane proteins and composition is tissue dependent.
What is collagen?
main structural protein in ECM. They are trimeric proteins with many different types. They associate in fibers, sheets or transmembrane interactions.
How are collagen molecules formed?
Three alpha helical chains are produced, they are formed in the ER into a triple helix shape by hydroxylation/glycosylation then secreted out to the extracellular space as procollagen. There they are cleaved and form collagen
What is scurvy?
when vit C is not present collagen will not be hydroxylized and will lose structural integrity. This results in tissues not forming properly so wounds reopen, body falls apart and you lose teeth
What is Ehlers-Danlos Syndrome?
Mutations in the genes for collagen synthesis alter the structure, production or processing of collagen and weakens connective tissues, skin, bones etc.
What are cell connections/junctions? (4)
Connections between neighboring cells that allow for mirgration, signaling, immunity etc- 4 types- anchoring, occluding, channel forming or signal relaying
What is the cadherin superfamily and what kind of cell interaction is it involved in?
They are Ca2+ dependent adhesion molecules that form desosome and adheren junctions between cells. They use actin and intermediate filaments.
What is the purpose of cadherin junctions?
To form “sheets” between cells. Help in shaping the tissues/ provide tension and durability.
Examples of cadherin superfamily
e-cadherin- epithelial
N cadherin- neural
VE- cadherin- vascular endothelial
What is EMT in caherins?
Epithelia to Mesenchymal Transition- used to determine if there are invasive metastatic tumors. There will be a decrease in E cadherin for N cadherin
What is the IG superfamily and what is its function?
Calcium independent transmembrane glycoproteins that are heavily involved in immune cell interactions.
What are selectins?
Calcium dependent glycoproteins that bind to extracellular carbs. They are important in host defense. They will increase during inflammatory response
What are integrins?
They are heterodimeric molecules involved in cell junctions. They couple the cell matrix to cytoskeleton and activate cell signaling pathways
