ex22 Flashcards
What is Notch signaling?
A mechanism where the Notch receptor binds its ligand on a neighboring cell, leading to cleavage of the Notch intracellular domain (NICD), which translocates to the nucleus and regulates transcription.
What is Wnt signaling?
A pathway where Wnt proteins bind Frizzled receptors, stabilizing β-catenin, which enters the nucleus and influences target gene expression.
How do gap junctions affect gene expression?
They allow direct cytoplasmic connections for small molecules and ions to pass between cells, enabling coordinated gene expression.
How is mRNA degradation regulated?
By deadenylation, decapping, and exonucleolytic digestion.
What role do miRNAs play in mRNA regulation?
They bind complementary mRNA sequences to induce degradation or translational inhibition.
How does alternative splicing affect protein function?
It generates multiple mRNA isoforms, leading to proteins with distinct domains and functions.
What is the function of GPCRs?
They detect external signals like hormones or odors and activate intracellular pathways.
How is GPCR signaling activated?
Ligand binding causes a conformational change, activating the G-protein by GDP-GTP exchange.
How is GPCR signaling inactivated?
GTP hydrolysis on the Gα subunit, receptor phosphorylation by GRKs, and arrestin binding terminate signaling.
How do GPCRs assist in white blood cell migration?
They detect chemokines, activate cytoskeletal reorganization, and enable chemotaxis towards infection sites.
What controls the cell cycle via proteolysis?
Cyclin degradation by ubiquitination and cohesin cleavage by separase.
What is the role of BCL2 family proteins?
They regulate mitochondrial membrane permeability during apoptosis.
How can BCL2 contribute to cancer?
Overexpression of anti-apoptotic BCL2 proteins prevents cell death, aiding tumor survival.
What are plasmodesmata?
Structures in plants that allow direct cytoplasmic communication between cells.
How does the Rb protein prevent cancer?
By inhibiting E2F transcription factors, it prevents uncontrolled entry into the S-phase of the cell cycle.
