Molec and Cell 3 Flashcards
Intracellular signals definition
signals within a cell
Intercellular signals definition
signals between cells
Ligands definition
signals that bind other molecules on target cells
Four categories of signaling
Paracrine
Endocrine
Autocrine
Direct signaling across gap junctions
Paracrine signaling definition
move by diffusion through extracellular matrix
examples include synaptic signals and neurotransmitters
intercellular
Endocrine signaling definition
signals from distant cells, typically produce a slower response with a long-lasting effect
e.g., hormones
intercellular
Autocrine signaling definition
signaling cells that can also bind to the ligand that is released, such that signal and target cell can be the same or similar to each other
e.g., cell death signaling
intracellular
Direct signaling across gap junctions definition
intracellular mediators that allow small signaling molecules to move between cells
intercellular
Internal receptors definition
hydrophobic signaling molecules that typically diffuse across the plasma membrane and interact with intracellular receptors in the cytoplasm
e.g.; DNA and gene expression in nucleus
Cell-Surface Receptors definitions
ligands for these receptors are typically not hydrophobic and would react to the plasma membrane if not for these receptors
might be water soluble or gas
Cell-Surface Receptors Types
Ion channel-linked receptors
G-protein-linked receptors
Enzyme-linked receptors
Ion channel-linked receptors definition
ligands that signal the channel to open or close.
G-protein-linked receptors definition
ligands that bind to these receptors can help regulate many processes
in this case, they help create GTP by hydrolyzing it to GDP, like ATP and ADP
Enzyme-linked receptors definition
ligands help regulate enzymatic activity
e.g.; receptor tyrosine kinase
Receptor tyrosine kinase steps
- ligand binds to enzyme causing it to dimerize
- Tyrosine residues on the back end of enzyme on the intracellular domain are then autophosphorylated, triggering a downstream cellular response
- signal is terminated by a phosphatase that removes the phosphates from the phosphotyrosine residues
Tyrosine kinase function
receptors mediating cell-to-cell communication and controlling a wide range of complex biological functions, including cell growth, motility, differentiation, and metabolism
Signaling molecule definition
Small hydrophobic ligands so they can diffuse directly across the plasma membrane into the cell, where they interact with internal receptors
might be gas or water soluble
steroid hormones have similar chemical structures to their precursor, cholesterol
Three types of signaling molecules
Cholesterol
Testosterone
Estradiol
Propagation of the Signal Types
Signal transduction
Dimerization
Signaling pathway
Signal integration
Signal transduction definition
when a ligand binds to a receptor and the signal is transmitted through the cell membrane and into the cytoplasm continuing the signal
Dimerization definition
two receptors bind to each other to form a stable complex
Signaling pathway definition
chain of events including second messengers, enzymes and activated proteins that follow ligand binding to a receptor
Signal integration definition
signals from two or more different cell-surface receptors merge to activate the same response in the cell
Signaling pathway best example
epidermal growth factor (EGF) receptor (EGFR) is a receptor tyrosine kinase involved in the regulation of cell growth, wound healing, and tissue repair
if EGFR is activated at inappropriate times, uncontrolled cell growth (cancer) may occur
