Cell signalling

• the blood glucose system is a negative feedback loop
• activating platelets is a positive feedback loop
• the key elements of cell signaling are: signal, receptor, effector
• a ligand is a molecule that binds to a receptor and activates it
• it is false that all cells can respond to all signals
• it is false that a chemical signal produces the same response in all cells that bind the receptor
• post-translational modification alters the protein's function
• nuclear receptor ligands are hydrophobic because they need to diffuse across membrane to get to target
• adenylyl cyclase is often the target of G-protein-coupled receptors
• direct signaling needs gap junctions
• Neurotransmitters are released into the synapse from the presynaptic membrane
• When a K+ channel opens the cytosolic K+ concentration decreases
• paracrine signaling targets cells close to but not touching the releasing cell
• autocrine signaling involves the release of signaling molecules that act on the same cell that released them
• G protein-coupled receptors (GPCRs) are involved in paracrine signaling
• signal transduction is a process that transmits a signal inside a cell
• ligand-gated ion channels work by moving ions down the concentration gradient and is an example of intracellular signaling pathway
• G-protein-coupled receptors are second messenger signals
• kinase-linked receptors are are activated by binding of ligands, causing phosphorylation
• nuclear receptors bind directly to DNA
• autocrine signaling is a cell causing a change within itself to cause mitosis or other effects
• paracrine signaling is when cells release chemicals into their environment which affects nearby cells
• endocrine signaling is where hormones are released from endocrine glands and travel through bloodstream to target organs/tissues