Celbiologie
Chapter 9 Cellular Signaling
Concept 9.1 External Signals
⚠ Cells register signals en uses them to respond to it. This is called cell
signaling.
Evolution of Cell Signaling
For yeast cells, there are two mating types (sex types), a and 𝛂. Each type
secretes a specific factor that binds only to receptors on the other type of cell.
When these signals bind to the other cell, they can fuse together. This forms
a /𝛂 cells which contain genes of both cells.
Local and Long-Distance Signaling
Multicellular organism usually communicate via signaling molecules targeted
for cells that may or may not be immediately adjacent. Eukaryotic cells may
communicate via local signaling:
Both animal and plant cells have cell junctions that directly connect the
cytoplasm of adjacent cells.
Celbiologie 1
, Animal cells may communicate via direct contact between membrane
bound cell-surface molecules, in a process called cell-cell recognition.
In paracrine signaling, molecules travel short distances to another cell.
Growth factors are compounds that stimulate nearby target cells to
grow and divide.
Synaptic signaling is more specialized and occurs in the nervous
system. An electrical signal along a nerve cell triggers the secretion of
neurotransmitters.
Plant and animals use hormones for long-distance signaling. Hormonal
signaling is also called endocrine signaling, specialized cells release
hormones, which travel through the blood stream to target cells.
Plant hormones sometimes travel in plant vessels but often reach target
cells by moving through cells by diffusion.
Concept 9.2 Reception
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