Tissue Architecture Flashcards
Cytoskeletal function on the tissue level
- muscle movement
- muscle contraction
Cytoskeletal function on the cellular level
- cell morphology
- cell shape
- motility
- cell adhesion
- cell division
Cytoskeletal function on the subcellular level
- organization
- tensile strength
- chromosome segregation
- cell polarity
- vesticular movement
Cytoskeletal filaments are ______ and ______
Dynamic and adaptable
* can be broken down by a signal and reassembled at new sites
Thermal Stability of cytoskeletal filaments is derived from what characteristic
Filaments do not exist as a single filament but instead exist has thermally stable multi filament complex
Staggered long subunits give rise to a _____ characteristic of cytoskeletal filaments that give it its strong nature
Rope like properties
*allow it to stretch and bend
*intermediate filaments are resistant to stretching forces
What are the three main types of cytoskeletal filaments ?
- intermediate filaments
- Microtubules
- Microfilaments
Microfilaments are made up of
Actin
Microtubules are made up of
Tubulins
Intermediate filaments are made up of
Lamin and cell specific proteins
What is the function of intermediate filaments ?
Increase the tensile strength of cytoskeleton from rope like properties
-enable cells to withstand mechanical stress
Where are intermediate filaments found ?
In the cytoplasm of most animal cells
*surround the nucleus and extend into periphery
Often anchored to plasma membrane and cell-cell junctions
Intermediate filaments form mesh-like structure called the _____
Nuclear lamina
*strengthens nuclear envelope
Describe the route in which an intermediate filament grows
Alpha helical monomer -> coiled-coil dimer -> staggered tetramer of 2 coiled-coil dimers -> lateral association of 8 tetramers —> addition of 8 tetramers to growing filament ends
What are the two main, broad types of intermediate filaments
Cytoplasmic and nuclear
What are examples of cytoplasmic intermediate filaments
- Keratin filaments (in epithelial cells)
- Vimentin and vimentin-related filaments (in CT, muscle, and glial cells)
- Neurofilaments (in nerve cells)
What is the one type of nuclear intermediate filament
Nuclear Lamins
In all animal cells
What disease can be caused if there is destruction to the nuclear lamina that protects the cell
Progeria (accelerated aging)
What is the difference between nuclear lamin and lamina
Nuclear lamins, also known as Class V intermediate filaments, are fibrous proteins providing structural function and transcriptional regulation in the cell nucleus. Nuclear LAMINS interact with membrane-associated proteins to form the nuclear LAMINA on the interior of the nuclear envelope.
What is the function of microtubules?
*crucial eukaryotic cell organization
- forms mitotic spindle for chromosome segregation in mitosis
- part of cilia/flagella
- extends from centrosome to cell periphery to transport cellular components (in non-dividing cells)
Long and stiff, hollow tubes that can be rapidly assembled and disassembled refer to which cytoskeletal filament
Microtubules
A tubulin heterodimer unit is made up of what two subunits? And a tubulin heterodimer is a subunit for what structure ?
Alpha-tubulin and beta-tubulin
A protofilament
Which is a subunit for a microtubule
A microtubule had a plus end a minus end. Which side grows faster?
The plus end grows faster, the minus end grows slower
What is the role of gamma-tubulin in the nucleation of microtubules at the minus end
Gamma-tubulin is the anchor point of the minus end from which the plus end can grow in the opposite direction.
-nucleating sites have gamma-tubulin ring complexes surrounding a pair of centrioles in which microtubules grow at their plus ends
What is the microtubule-specific drug that binds and stabilizes microtubules and is beneficial for stopping cancer growth
Taxol
What are the two microtubule specific drugs that bind tubulin dimers and prevents their polymerization
Colchicine (Colcemid) and vinblastine (vincristine)
Microfilaments are composted of actin filaments (F-actin) which is comprised of
Twisted polymer of G-actin
*has structural polarity (plus and minus end)
T/F
Many microfilaments are unstable but association with other proteins can form stable structures
True
T/F
Microfilaments are essential for cell movement
True
What actin specific drug binds and stabilizes the filaments and is present in death cap mushrooms
Phalloidin
What actin specific drug caps filament plus ends and prevents polymerization
Cytochalasin
What actin specific drug binds actin monomers and prevents their polymerization
Latrunculin
Whose components are produced intracellular lay and secreted outside of the cell where they aggregate and is made of interlocking fibrous proteins and proteoglycans
Basal lamina (a component of the extracellular matrix)
“Basement membrane”
*very tissue specific
The extracellular matrix interacts with cells and tissues via ________ proteins
Transmembrane proteins
The basement membrane (Extracellular matrix) is made up of what proteins
Proteoglycans
Collagen (IV)
Laminin
Fibronection
What are the functions of the ECM ?
- Anchoring and engulfing cells to maintain structure
- Determining biochemical properties of extracellular environment
- Controlling cellular polarity, survival, proliferation, differentiation and fate
- Inhibiting or facilitating cell migration
- Binding and acting as a reservoir of growth factors
- Serving as a ligand for signaling receptors
What is the main structural protein in ECM/ connective tissue and basal lamina
Collagen
*triple helix gives its strength
What are the trimeric proteins that form collagens triple helix, and allow it to associate as fibers, sheets, or transmembrane structures
Homotrimers and heterotrimers
T/F
Collagen is not functional until it is cleaved
True
Where is the synthesis of preprocollagen; and insertion of procollagen molecule into the lumen of the ER
Rough ER
Where is collagen proline and lysine residues hydroxylated and hydroxylysine residues glycosylated
Lumen of the ER
Where is self-assembly of the tropcollagen molecule that is initiated by disulfide bond formation which forms the triple helix of collagen
Lumen of ER and Golgi apparatus
Where is procollagen prepared for secretion from the cell
Secretory vesicle
Where does the cleavage of propeptides of procollagen to make active collagen occur
Extracellular
Scurvy is a result of the loss of what cofactors of collagen production
Ascorbate (vitamin C)
Or iron
*cofactos that hydroxylate collagen
What are characteristic traits of scurvy
Poor wound healing Wound re-opening Loss of teeth Pale teeth Sunken eyes Bleeding gums
What disease is caused by. Mutations in collagen or collagen synthesis genes
Ehlers-Danlos syndrome
-stretchy skin
- Autosmal recessive is all enzyme defects
- autosomal dominant is all structural (fibrous) proteins are defective
[fibrous proteins all start with COL]
_____ links cells to ECM (basil lamina)
Focal contacts
What are different types of cell connections and junctions that serve roles in migration, wound healing, tissue architecture, and immune system function
Anchoring junction
Occluding junction (prevents passage of molecules)
Channel-forming junction
Signal relaying junction
What are desmosomes
An anchoring junction made up that connects cell to cell and is a part of intermediate filaments. Give the cell strength
What are adheren junctions
An anchoring junction that binds cell to cell. Uses Cadherin receptors and attaches to actin filaments. Give the cell shape
Gap junctions have connexins principle receptors and are important for what function of the body
Heart contraction
What are the 4 major families of cell-adhesion molecules (CAMs) and adhesion receptors
- Cadherins
- Ig superfamily CAMs
- Integrins
- Selectins
What are the 3 major domains of CAMs
- Extracellular
- binds adjacent cell to matrix protein - Transmembrane
- links CAM to membrane - Cytoplasmic
- bind to cytoskeleton via linker proteins
The cadherin superfamily is a __ dependent adhesion molecule, and has what important function
Ca2+
- important in the formation of adheren and desmosome junctions between cells (epithelial “sheets”)
- has homophilic interactions
- interacts with actin cytoskeleton
What are the common features of classic cadherins
(Types E, N, R, VE)
-Ca2+ dependent homophilic adhesion function that links to the actin cytoskeleton and is associated with adheren junctions
What are common features of atypical cadherins
(T and Ll type)
-function as homophilic adhesion proteins without interaction with catering or link to actin cytoskeleton
E-cadherin =
Epithelial
N-cadherin =
Neural c
VE-cadherin =
Vascular-endothelial
Li cadherin =
Liver-intestine
Cadherins can serve as biomarkers for invasive metastic tumors. In EMT (epithelia to mesenchymal transition) which is present in bladder cancer, which cadherins are increased and which are decreased
E cadherins decrease
N cadherins increase
*signals increased tumor invasiveness and increased metastatic potential
The Ig superfamily of CAMs is calcium independent transmembrane glycoproteins that interacts with what type of cells through what type of binding
- Immune function cells
- homophilic and heterophilic binding
- involved in recognition, binding, and adhesion of cells
Selectin (CAMs) are calcium dependent glycoproteins that bind to extracelluar ______. And play an important role in what
- Carbohydrates
- in host defense mechanism (increasing inflammation so WBC can start leukocyte rolling cascade)
[therefore an increase in inflammatory responses = an increase in selectins]
Integrins (CAMs) bind what together
The ECM to the cytoskeleton
Integrins (CAMs) activate what signaling pathways
RTK to regulate growth, division, survival, and apoptosis
Integrins (CAMs) have cell to cell interactions via _____ family
Beta-2 family
*integrins on leukocytes allow for adhesion and transmigration to sites of infection
