5. Other Structural Elements of the Cell Flashcards
What are receptors?
important class of integral membrane proteins that transmit signals from the extracellular space into the cytoplasm
What is a ligand?
molecule that serves as the key for a given receptor
What is signal transduction?
response within a cell that occurs when a ligand binds to its receptor
What are the three main types of signal-transducing cell-surface receptors?
ligand-gated ion channels
catalytic receptors
g-protein linked receptors
What are ligand gated ion channels?
open an ion channel upon binding a particular neurotransmitter
What is a catalytic receptor?
enzymatic active site on the cytoplasmic side of the membrane that will be initiated by ligand binding at the extracellular surface
What is a G-protein linked receptor?
transmits a signal into the cell with the aid of a second messenger
What is a second messenger?
chemical signal that relays instructions from the cell surface to enzymes in cytoplasm
What is the cytoskeletons purpose?
provides the structural support supplied by the cell wall in bacteria, plants, and fungi
What three proteins comprise animal cell cytoskeletons?
microtubules
intermediate filaments
microfilaments
What are microtubules?
hollow rods composed of two globular proteins alpha tubulin and beta tubulin that are polymerized noncovalently
What are centrioles?
a ring of nine microtubule triplets that are located within the MTOC and ensure each daughter cells receives one copy of the replicated chromosomes
What is an aster?
microtubules that radiate out from the centrioles during mitosis
What are polar fibers?
microtubules that connect the chromosomes to the aster
What is the mitotic spindle?
entire assembly of centrioles, aster, and polar fibers
