Signals and Receptors Flashcards
What are the 5 major classes of intercellular communication? Rank them from closed(private) to open(public) intercellular (between) communication
Closed = specific and reliable, helps ensure that signal is received by appropriate target (direct connection)
Open = critical for integration of response from cells in the distantly located target organs (broadcast)
Gap Junction
Contact Signaling (juxtacrine)
Synaptic signaling
Paracrine signaling
Endocrine signaling
Choose the best option
(Gap Junction/Contract Signaling/Synaptic Signaling/Paracrine Signaling/Endocrine signaling)
- This communication is important in tissue
- Need to be synchronous
- Form pores
- Composed of Connexin proteins
- only small molecules
- Important Physiological molecules that pass thru, ATP and Ca2+
Gap Junction
Choose the best option
(Gap Junction/Contract Signaling/Synaptic Signaling/Paracrine Signaling/Endocrine signaling)
- Differ by gap junction but temporary signals
- Some examples that use this signaling, blood, and fertilization
Contract Signaling (juxtacrine)
Choose the best option
(Gap Junction/Contract Signaling/Synaptic Signaling/Paracrine Signaling/Endocrine signaling)
- Cell are virtually in contact
- This signal is released as a chemical from the pre-synaptic cell to the extracellular (synapse)
- Target cell (synaptic cell or muscle cell)
- Synapse can be destroyed and reform
Synaptic Signaling
Choose the best option
(Gap Junction/Contract Signaling/Synaptic Signaling/Paracrine Signaling/Endocrine signaling)
- Signal release in extracellular and disperse to many cells
- Signal is retained locally and eliminate locally
Paracrine Signaling
Choose the best option
(Gap Junction/Contract Signaling/Synaptic Signaling/Paracrine Signaling/Endocrine signaling)
- Travel thru the blood and target the cell that contain the same receptors
- Signals are mixed in the blood
- Depending on the receptor if the signal the signal will bound to the specific receptor
- Each cell with different type of receptor will have a different response
Endocrine Signaling
What is the primary distinction between signaling pathways that operate on fast vs slow time scales, as to how changes in cell phenotype are achieved?
fast signaling
It is reversible changes in existing proteins
Happen very quick, but does not last long
Slow signaling
Change the function of a new protein because signal comes as a transcription factors
More permeant change, change phenotype or change behavior, take longer but long-lasting
What is one example of how different cell types can respond differently to the same signals?
The roles of Acetylcholine in different cell types like
heart pacemaker cell (decrease rate of firing)
salivary gland cell (secretion)
Skeletal muscle cells (contractions)
Scientists looked at different types of drug (nature and synthetic) and their interaction with the AChR in these cells
What is the overall General chemical property of most signals and how does this impact their signaling?
- Water Soluble (hydrophilic)
- Can not cross cell membranes due to plasma membranes and any intracellular membranes (need transporter)
- Signal are present in blood fluids in very low levels
- Rapidly turn over –> Do not persist for long peroids
- Important as many responses need to be rapdily reversible
Why Signals with short half-lives is important in obtaining rapid and reversible changes in signal levels?
Looking at these two graphs
Left Graph: The unstable signal eliminates real quick (1 min) in the blood which is important as many responses need to be rapidly reverisble.
The stable signal does not affect the blood that much, it is stable throughout the graph.
Right Graph: The low levels of signal in the blood, unstable signal will have a high turn over rate.
The stable signal had a very low turn over rate.
What is the relationship between the levels and half-lives of signals as to how they are tuned to the properties of receptors and blood throughout the body?
It takes about one minute for blood to make the round trip to the heart
What are the diverse chemical classes that can act as intercellular and extracellular signals and how the chemical nature of the signal can impact signaling?
(from the slides that we do not need to memorize)
INTERCELLULAR SIGNALS
Peptides/Proteins
oligopeptides
Proteins
Polypeptides
Glycoproteins
Small Molecules
Amino acids
Catecholamines
Thyroid Hormones
Steroids
ALL OF THESE SIGNALS ARE WATER SOLUBLE AND THEY CAN NOT ENTER THE CELL
THE ONLY EXCEPTION IS STEROID SIGNALS (WATER INSOLUBLE AND CAN ENTER THE CELL)
EXTRACELLULAR SIGNALS
MEDIATE INTERCELLULAR SIGNALING
MANY DIFFERENT CHEMICAL FORMS
MOST ARE WATER SOLUBLE, SO IT CAN’T CROSS THE PLASMA MEMBRANE NEED INTERACTION WITH TRANSMEMBRAEN RECEPTOR TO TRANSMIT SIGNAL TO CELL INTERIOR
What are the functions of receptors?
- Bind correct signal/ligand present in extracellular fluid through an extracellular domain
- Transmit information that ligand is bound to the interior of the cell by a change in function in an intracellular receptor domain
Why are receptors typically transmembrane proteins?
To be very accurate
Need to be able to sense changes in concertation of a specific signal present at very low levels
True/False
The receptor must operate via allosteric conformational changes that transmit information from the ligand bind site
True
