Understand types of signaling, receptors, and signaling molecules
AP Biology · Learn by Concept
Help Questions
AP Biology › Understand types of signaling, receptors, and signaling molecules
Which type of ligand is water soluble, and thus unable to enter a cell?
Small, hydrophobic ligands
Water-soluble ligands
Nitric oxide
steroid hormones
Explanation
The membrane of the cell is a phospholipid bilayer, which allows hydrophobic molecules to diffuse through it. Small, hydrophobic ligands are able to diffuse through the plasma membrane. Nitric oxide is lipophilic, readily dissolving in lipids, and can diffuse across the plasma membrane. Steroid hormones are hydrophobic, and can thus diffuse across the plasma membrane. Water-soluble ligands cannot diffuse across the plasma membrane to enter a cell.
What type of signaling uses the bloodstream to transport ligands to targets?
Direct
Endocrine
Paracrine
Autocrine
Explanation
Endocrine signals are signals from distance cells that move using the bloodstream, paracrine signals are signals used to communicate between cells in close proximity, autocrine signals are signals that are received by the same cell in which the signal originated, and direct signaling occurs across gap junctions through the movement of small molecules (such as Calcium ions).
Which is false regarding cell signaling?
Endocrine signals move via the bloodstream
Paracrine signals are used to communicate the nearby cells
Autocrine signals bind to receptors on the same cell that released the ligand
Paracrine signals are long-lasting
Explanation
Endocrine signals are signals from distance cells that move using the bloodstream, paracrine signals are signals used to communicate between cells in close proximity, and autocrine signals are signals that are received by the same cell in which the signal originated. Paracrine signals are signal are short-lasting, whereas endocrine signals are long-lasting.
Which type of cell-surface receptor, when bound by a ligand, begins a cycle where GDP is exchanged for GTP, causing the alpha subunit to separate from the beta and gamma subunits, and causing a cellular response?
GTP hydrolyzation receptor
Ion channel- linked receptor
G-protein linked receptor
Enzyme-linked receptor
Explanation
G-protein linked receptors are a type of cell-surface receptor that, when unbound by a ligand, consists of an alphaGDP subunit and a beta gamma subunit. When a ligand binds, GDP is exchanged for GTP, which causes the alphaGTP subunit to dissociate from the receptor and the beta gamma subunit. Then, the alphaGTP and beta gamma subunits can activate other molecules in the cell.
A cell releases a ligand that binds to receptors on its own surface. Which type of signaling is this?
Autocrine
Endocrine
Paracrine
Direct
Explanation
Endocrine signals are signals from cells that move using the bloodstream and signal to distant cells, paracrine signals are signals used to communicate between cells in close proximity, autocrine signals are signals that are received by the same cell in which the signal originated, and direct signaling occurs across gap junctions through the movement of small molecules (such as Calcium ions).
Beta cells in the pancreas secrete insulin, a hormone, that enters the bloodstream. This is an example of which type of signaling?
Direct
Autocrine
Paracrine
Endocrine
Explanation
Endocrine signals are signals from cells that move using the bloodstream to signal to distant cells, paracrine signals are signals used to communicate between cells in close proximity, autocrine signals are signals that are received by the same cell in which the signal originated, and direct signaling occurs across gap junctions through the movement of small molecules (such as Calcium ions). Beta cell in the pancreas produce insulin, a hormone, which is secreted into the bloodstream.