Chapter 11 Terms Flashcards
Apoptosis
A type of programmed cell death, which is brought about by activation of enzymes that break down many chemical components in the cell.
cyclic AMP (cAMP)
Cyclic adenosine monophosphate, a ring-shaped molecule made from ATP that is a common intracellular signaling molecule (second messenger) in eukaryotic cells. It is also a regulator of some bacterial operons.
diaclyglycerol (DAG)
A second messenger produced by the cleavage of the phospholipid PIP2 in the plasma membrane.
hormone
In multicellular organisms, one of many types of secreted chemicals that are formed in specialized cells, travel in body fluids, and act on specific target cells in other parts of the body, changing the target cells’ functioning. Hormones are thus important in long-distance signaling
inositol trisphosphate (IP3)
A second messenger that functions as an intermediate between certain signaling molecules and a subsequent second messenger, Ca2+, by causing a rise in cytoplasmic Ca2+ concentration.
local regulator
A secreted molecule that influences cells near where it is secreted.
protein kinase
An enzyme that transfers phosphate groups from ATP to a protein, thus phosphorylating the protein.
protein phosphatase
An enzyme that removes phosphate groups from (dephosphorylates) proteins, often functioning to reverse the effect of a protein kinase.
second messengers
A small, nonprotein, water-soluble molecule or ion, such as a calcium ion (Ca2+) or cyclic AMP, that relays a signal to a cell’s interior in response to a signaling molecule bound by a signal receptor protein.
Communication between mating yeast cells
- Exchanging of mating factors: Each cell type secretes a mating factor that binds to receptors on the other cell types.
- Mating: Binding of the factors to receptors induces changes in the cells that lead to their fusion.
- New a/alpha cell: The nucleus of the fused cell includes all the genes from the a and alpha cells
Communication by direct contact between the cells
- Cell junctions
- Cell-cell recognition
Local signaling
- Paracrine signaling
- Synaptic signaling
Long-distance signaling
Endocrine (hormonal) signaling
Overview of cell signaling
- Receptor
- Transduction
- Response
A phosphorylation cascade
- A relay molecule activates protein kinase 1.
- Active protein kinase 1 transfers a phosphate from ATP to an inactive molecule of protein kinase 2, thus activating this second kinase.
- Active protein kinase 2 then catalyzes the phosphorylation (and activation) of protein kinase 3.
- Finally, active protein kinase 3 phosphorylates a proton that brings about the cell’s response to the signal.
- Enzymes called protein phosphatases (PP) catalyze the removal of the phosphate groups from the proteins, making them inactive and available for reuse.