chapter 11

Chapter 11
1) How does cell communicate?
Cells communicate with other cells by using signals.
2) Why does cell need communicate?
Because cells need to regulate themselves and Environmental Stimuli cells need to be able to respond to signals from their environment.
3) How many different signals are there?
There are local signals, they are paracrine signaling and synaptic signaling. And there is long distance (hormonal) signal.


Factors
!) There are three stages of cell signal. Reception is receiving signals. Transduction is passing on the signal. Response is cellular changes because of the signal.
2) In reception, The target cell’s detection of a signal coming from outside the cell. May occur by:
direct Contact and through signal molecules
3) direct contact means when molecules can flow directly from cell to cell without crossing membranes. For example, in plants there are plasmodesmata and in animals there are gap junctions.
4) Signal molecules are the actual chemical signal that travels from cell to cell. And they often water soluble, usually too large to travel through membranes. Double reason why they can’t cross cell membranes.
5) Reception molecules are usually made of protein. Change shape when bind to a signal molecule and transmits information from the exterior to the interior of a cell.

Summary
External signals are converted to responses within the cell. There are three stages of cell signaling. They are reception, transduction and response. Reception is a signaling molecule binds to a receptor protein, causing it to change shape. Transduction is cascades of molecular interactions relay signals from receptors to target molecules in the cells. Response is cell signaling leads to regulation of transcription ore cytoplasmic activities. Apoptosis integrates multiple cell-signaling pathways.

Diagram
In this diagram we can see there’re two kind of cell signaling, local signaling and long distance signaling. In local signaling there are paracrine signaling and synaptic signaling. And the long distance signaling is normally for hormonal.

Key terms
1. Signal transduction pathway: The process by which a signal on a cell’s surface is
converted to a specific cellular response.
2. Cell-cell recognition: Two cells in an animal may communicate by interaction
between molecules protruding from their surfaces.
3. Synaptic signaling: A nerve cell releases neurotransmitter molecules into a
synapse, stimulating the target cell. (Local signaling)
4. Local regulators: A secreted molecule that influences cells near where it is
secreted.
5. 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 to change their functioning.
6. Reception: It is the target cell’s detection of a signaling molecule coming from
outside the cell.
7. Transduction: The binding of the signaling molecule changes the receptor protein
in some way, initiating the process of transduction.
8. Response: The transduced signal finally triggers a specific cellular response. In
cellular communication, the change in a specific cellular activity brought about by
a transduced signal from outside the cell.
9. Protein Kinase: An enzyme that transfers phosphate groups from ATP to a protein,
thus phosphorylating the protein.
10. Cyclic AMP: Also known as cAMP. It is 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.

http://www.youtube.com/watch?v=U6uHotlXvPo