Chapter 11 Flashcards
Protozoa are ________.
Autonomous
Cell communication is necessary for _________ and ________ of tissues and organs.
Structural, functional integrity
Signal transduction
Process by which a cell converts an extracellular signal into a response
Hormone
An information-carrying molecule that is secreted from a cell, circulates in the body, and acts on target cells far from the signaling cell.
Cell signaling process:
- Reception
- Transduction
- Response
Transduction
Cascades of molecular interactions relay signals from receptors to target molecules in the cell
Ligand
Signal molecule
Three main types of membrane receptors:
- G-protein-linked receptors
- Receptor tyrosine kinases
- Ion channel receptors
G-proteins
Peripheral membrane proteins located inside the cell that are closely associated with transmembrane signal receptors
_________ acts as an on/off switch
G-protein.
They are activated when they bind GTP and are deactivated when they hydrolyze the bound GTP to GDP.
Second Messengers
Intercellular signaling molecules that diffuse rapidly throughout the cell, amplifying the signal
Most common are cyclic AMP (cAMP) and Ca++ (more frequent than cAMP)
Growth factors and local regulators that stimulate cells to grow and reproduce are often mediated by __________.
Tyrosine-kinase receptors
G-protein compared to thyrosine-kinase
Thyrosine-kinase receptor can activate many signal transduction pathways simultaneously.
The G-protein receptor only activates a single pathway at a time.
Relay molecules
Molecules that relay the signal from the receptor to the response.
The signal that is passed from one molecule to another usually results in ___________ of proteins along the pathway.
Conformational changes
Apoptosis
Programmed or controlled cell suicide. It prevents enzymes from leaking out of a dying cell and damaging neighboring cells.
Proteases
Enzymes that cut up proteins
How can apoptosis be triggered?
- An extracellular death-signalling ligand
- DNA damage in the nucleus
- Protein misfolding in the endoplasmic reticulum
