Modules 21-25 Exam Study Guide PDF

Exam Study Guide Module 21 ECM degradation during cell migration assists in clearing paths, exposing binding sites, and promoting detachment, facilitating movement. Fibrous proteins are characterized by their water-insoluble and extended structures, which provide structural function...

Exam Study Guide Module 21 ECM degradation during cell migration assists in clearing paths, exposing binding sites, and promoting detachment, facilitating movement. Fibrous proteins are characterized by their water-insoluble and extended structures, which provide structural functions, unlike compact structures. Globular proteins have compact structures and are often soluble, while fibrous proteins are extended and provide structural support. Propeptides are removed after collagen is secreted, allowing the formation of collagen fibrils in the ECM. Laminin is the principal adhesive protein in epithelial tissues, playing a key role in cell adhesion and maintaining tissue structure. Proteoglycans sequester soluble signals and bind to cell surface receptors, influencing cell fate and behavior in the ECM. Adhesive proteins such as fibronectin primarily function to link cells to the ECM, facilitating cell adhesion and communication. Module 22 The basal lamina in the kidney glomerulus acts as a filter, preventing the passage of macromolecules from the blood into the urine. Type I collagen is primarily found in connective tissues, while type IV and VII collagens, along with laminin, are key components of the basal lamina. Dystrophin is crucial for linking the actin cytoskeleton of muscle fibers to the basal lamina, maintaining muscle integrity. Type IV collagen is a major component of the basal lamina, providing structural support and organization. Type I collagen is known for providing tensile strength. Type II collagen is involved in fibril interaction. Type IV collagen is part of the basement membrane (Basil Lamina). Type VII collagen is associated with epidermis adhesion When dystrophin is absent, the dystrophin-associated protein complex (DAPC) becomes destabilized, leading to muscle damage Mutations in type IV collagen can lead to muscle-wasting diseases, as this collagen is essential for the structural integrity of the basal lamina. Module 23 Inside-out signaling occurs when an intracellular activator binds to the β-subunit of integrins, inducing a conformational change that increases affinity for extracellular ligand. Integrins are heterodimers that function as both cell adhesion molecules (CAMs) and receptors, facilitating interactions with the extracellular matrix. The immunoglobulin superfamily (IgSF) mediates Ca²⁺ independent cell-cell adhesion and can interact with integrins and other IgSF proteins. Integrin signaling can activate intracellular tyrosine kinases such as FAK and SRC, which play roles in various cellular processes. Exam Study Guide Selectins contain a carbohydrate-binding domain that recognizes glycoproteins and glycolipids on adjacent cells, facilitating transient interactions. The cytoplasmic domain of cadherins binds to catenins, which in turn bind to the actin cytoskeleton, linking cell adhesion to the cytoskeleton. Cadherins predominantly form homophilic interactions, meaning they bind to the same type of cadherin on adjacent cells, rather than heterophilic interactions. Outside-in signaling, initiated by the binding of ECM ligands to integrins, regulates cell polarity, survival, and other intracellular activities. Module 24 Desmosomes connect intermediate filaments, such as keratin, to provide structural integrity to tissues. In bullous pemphigoid, antibodies target hemidesmosomes, leading to the detachment of the epidermis from the basement membrane. Tight junctions and adherens junctions are predominantly found in epithelial tissues, providing barriers and connections. Adheres junctions are often described as belt-like structures that encircle cells near their apical surface. Gap junctions are formed by connexin proteins that create channels for communication between adjacent cells. Focal adhesions disassemble when cells move or enter mitosis, allowing for cell locomotion. Tight junctions not only create a barrier but also play a role in signaling by regulating the movement of proteins between cell membranes.. Gap junctions allow for the rapid transmission of electrical signals, which is essential for synchronizing contractions in heart muscle cells. Desmosomes are specifically designed to provide structural integrity in tissues that experience high mechanical stress. Hemidesmosomes occur at single locations, anchoring epithelial cells to the basement membrane, unlike other junctions that may be more widespread. Module 25 Integrins facilitate the epithelial-mesenchymal transition, which is a key process in metastasis. Integrins specifically recognize the RGD sequence on fibrinogen, which is crucial for binding and clot formation. Integrins mediate cell adhesion to the extracellular matrix (ECM), which is essential for various cellular functions. LAD – I characterized by leukocytosis, which is an elevated white blood cell count due to impaired leukocyte adhesion. β2-integrins bind to IgSF proteins on endothelial cells, facilitating firm adhesion of leukocytes during inflammation. Extravasation, also known as diapedesis, refers to the process where neutrophils move through the endothelial barrier to reach sites of damage. Impaired wound healing is a key characteristic of LAD - I due to the lack of functional leukocyte adhesion.