cell communication Flashcards
(9 cards)
cell signlaing overview
cells communicating for embryo patterning coordination motility and enviromental sensing
signal must pass through the plasma membrane to reach the inside of the cell
types of cell signaling
direct signal transfer - cells communicate through direct contact
local ( paracrine signlaing) signals are released to nearby cells
long distance signaling ( endocrine signaling) - hormones travel through the bloodstream to distant target cells
signal reception
G protein-coupled receptors - large fam of receptors that activate intracellular signaling cascades via G proteins
Ion channel receptors- open or close ion channels in response to ligands
intracellular receptors- located inside the cell; respond to small, nonpolar molecules like steroid hormones
signal transduction
singals are relayed inside the cell after receptros activation
phsoporylation cascades - protein kinases transfer phosphate groups to activate/inactivate proteins
signal amplification - a single signaling molecule can activate many molecules inside the cell
secondary messengers
help transmit the signal within the cell
ex: cAMP, IP3 and Ca 2+
Cellular response
the final step in signaling where the cell executes the action
What is a phosphorylation cascade, and how does it regulate cellular response?
A phosphorylation cascade is a sequence of signaling events in which one enzyme phosphorylates (adds a phosphate group to) another, triggering a chain reaction that amplifies and transmits a cellular signal. This cascade is initiated by an extracellular signal (ligand) binding to a receptor, which activates a protein kinase that phosphorylates subsequent kinases in the pathway. The cascade regulates cellular responses by amplifying the signal, ensuring a strong and coordinated response, and allowing for tight control through activation or deactivation of target proteins. This mechanism is crucial in processes like cell growth, metabolism, and immune responses.
A researcher discovers a new hormone that is small and nonpolar. Based on its properties, predict the type of receptor it would bind to and explain why.
A small, nonpolar hormone would bind to an intracellular receptor located in the cytoplasm or nucleus, rather than a membrane-bound receptor. Because it is nonpolar, it can easily diffuse through the hydrophobic lipid bilayer of the cell membrane without needing a transport protein. Once inside the cell, the hormone-receptor complex typically acts as a transcription factor, directly influencing gene expression.
Compare and contrast local (paracrine) signaling and long-distance (endocrine) signaling in terms of their mechanisms and effects.
Paracrine signaling is a form of local communication where signaling molecules (such as growth factors or neurotransmitters) diffuse short distances to affect nearby target cells, leading to quick and localized responses. In contrast, endocrine signaling involves hormones that travel through the bloodstream to reach distant target cells, resulting in widespread and often longer-lasting effects. While paracrine signaling is crucial for localized tissue responses like wound healing, endocrine signaling regulates systemic processes such as metabolism and growth.
