Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
29 Cards in this Set
- Front
- Back
|
1. What are the different names used to refer to signal producing and signal responding cells?
|
Signal producing: upstream, the sender, the inducer
Responding cell: downstream cell, the receiver, the responder |
|
|
2. What kind of cellular activity can be controlled by cell to cell communication?
|
Any cellular activity: migration, growth, proliferation, apoptosis, etc.
|
|
|
3. What are the four components common to all signal transduction pathways? What would happen to the pathway if any of these components were absent?
|
Upstream components: 1. Extracellular signaling molecule: the ligand (ligand biochemistry and mode of delivery);
Downstream components: 2. Receptor (on PM); 3. Intracellular signal transduction cascade; 4. Response The target mechanism would not result if any component is absent |
|
|
4. Briefly describe the following types of signaling.
|
Juxtacrine signaling: signaling to neighboring cell only
Paracrine signaling: local diffusion to target cells within same tissue – local/contained (NOT systemic/throughout body) Endocrine signaling: systemic, long-distance diffusion in circulatory system Synaptic signaling: systemic, short-distance diffusion; neurotransmitter signaling between a neuron and the synapse – highly specific |
|
|
5. Describe the ligands involved in each type of signaling.
|
Juxtacrine ligands: membrane-bound ligands (cell-to-cell), ECM molecules (ECM-to-cell), small cytoplasmic molecules if gap junctions (communicating junction to gap junction)
Paracrine ligands: growth factors (proliferation and differentiation), cytokines (i.e., small signaling proteins), gasses (NO and CO) Endocrine ligands: hormones (released into bloodstream) Synaptic ligands: neurotransmitters (released by neurons, received by neurons, muscle, etc.) |
|
|
6. What is autocrine signaling? How is it different from paracrine signaling?
|
Autocrine signaling: when a secreted molecule acts on the same cell that produces it; paracrine signaling acts on a cell different than the signal-originating cell
|
|
|
7. How are endocrine and synaptic signaling similar? How are they different?
|
They are similar in that they both act systemically on large, complex, multicellular organisms
They are different in that synaptic signaling is super-fast and more precise than endocrine signaling Synaptic molecules involve neurotransmitters and travel short distances and endocrine molecules involve hormones and travel long distances in the circulatory system |
|
|
8. What type of molecules are endorphins? What type of signaling do they participate in? What cell type releases them? What happens when endorphins are released by these cells? How are they involved in the placebo effect? What happens if endorphins are misregulated?
|
Endorphins are opioid CNS neurotransmitters
They participate in synaptic signaling Neurons release endorphins, which then bind to opioid receptors expressed in hypothalamus cells They signal to region of the brain that responds to pain and deals with emotions Placebo effect: ecpectation that something good is happening which tricks hypothalamus into releasing endorphins |
|
|
9. What type of molecule is ghrelin? What type of signaling does it participate in? What cell type releases ghrelin? Where are the cells that respond to ghrelin located? What is the function of ghrelin?
|
Ghrelin is a hormone produced by endocrine cells in the stomach Glands release hormones It participates in endocrine signaling The receptor is in the hypothalamus in the brain Ghrelin indicates hunger |
|
|
10. What type of molecule is leptin? What type of signaling does it participate in? What cell type releases leptin? Where are the cells that respond to leptin located? What is the function of leptin? How is leptin similar and different from ghrelin?
|
Leptin is a hormone release by adipose cells
It participates in endocrine signaling The receptor is on cells in the hypothalamus in the brain It serves to indicate fullness (stop eating) Ghrelin and leptin work in opposition to one another in body weight homeostasis, but both work on a common population of neurons in they hypothalamus |
|
|
11. What is the observed phenotype of mice with mutations in the gene that encodes leptin? What is the molecular basis of this phenotype?
|
Leptin mutations can cause a phenotype with a higher proportion of adipose cells as the mutation prevents leptin from signaling to the hypothalamus that the organism is full, therefore it continues eating
|
|
|
12. Leptin is produced in adipose cells, therefore obese individuals tend to have higher levels of leptin in circulation. However, in these individuals high leptin does not correspond to a reduction of food intake. Explain what might be going on.
|
There could be faulty leptin receptors, so although there is plenty of leptin circulating, the signal is not being received by the hypothalamus
|
|
|
13. What type of molecule is oxytocin? What type of signaling does it participate in? What cell type releases oxytocin? Where are the cells that respond to oxytocin located? What is the function of oxytocin?
|
Oxytocin is a hormone that participates in endocrine signaling
Cells in the hypothalamus release oxytocin and are received by various regions in the CNS Oxytocin facilitates pair bonding, birth, maternal bonding, lactation, decreases stress and anxiety |
|
|
14. What are the 5 general types of transmembrane receptor proteins?
|
Cell-adhesion transmembrane proteins
G-Protein-coupled receptors (GPCR) Enzyme-linked receptors Specialized growth factor receptors Ion-channel-coupled receptors |
|
|
15. What are GPCRs? What are G proteins? How do GPCRs function?
|
G-protein-coupled receptors
G-proteins are trimeric GTP-binding proteins that hydrolyze GTP to GDP Functions by regulating activity of another plasma-membrane-bound protein The G-protein mediates the interaction between GPCR and the target protein Causes indirect activation of enzymes through activation of G-protein |
|
|
16. Describe how enzyme-linked receptors function.
|
Enzyme-linked receptors directly activate enzymes
The receptor protein is either an enzyme itself (signal molecule activates dimeric receptor causing enzymatic activity) or associates directly with an enzyme (signal molecule binds, activating receptor, activating separate enzyme) |
|
|
17. How do ion-channels work? What is the most common ligand of these receptors?
|
Ions build up on one side of the plasma membrane, a signal molecule (neurotransmitter) activates the channel-receptors causing a conformational change, allowing passage of ions through the receptor
Also called transmitter-gated ion channel The most common ligand is a neurotransmitter and therefore is involved in rapid synaptic signaling |
|
|
18. What are the two types of intracellular receptors?
|
Nuclear receptors (transcriptional activators)
Soluble gas receptors (NO and CO) |
|
|
19. How do nuclear receptors work? What domain is common to all of these proteins? Why?
|
Nuclear receptors bind the ligand in the cytosol, translocate to the nucleus, and bind DNA to influence gene regulation
|
|
|
20. What is the nitric oxide (NO) receptor called and what are its two functions? Why is NO important in blood vessels? What would happen in the absence of NO or if guanlyl cyclase had an inactivating mutation?
|
The nitric oxide receptor is called Guanyly Cyclase
Two functions: Acts as intracellular receptor for NO AND as an intracellular signaling protein NO released by endothelial cells makes smooth muscle cells relax, which increases blood flow Without NO or guanlyl cyclase mutation, blood flow would decrease (restricted blood vessels) |
|
|
21. Why is it advantageous for signal transduction cascades to be so complex?
|
The higher the complexity of signal transduction cascades (the more steps), the higher the possibility of regulation and increase in coordination and integration of multiple signals
|
|
|
22. What is a scaffold protein?
|
Two or more signaling proteins moved together, interacting to move quickly and efficiently as one unit
Part of a signal transduction pathway that transduce and amplify signals received by PM receptors |
|
|
23. What are two common mechanisms used as molecular switches/relays?
|
Switching a protein on can relay the signal to the next signaling component
Phosphorylation: activation by kinases and deactivation by phosphatases GTP-binding: activation by exchanging bound GDP for GTP and deactivation by hydrolyzing bound GTP to GDP |
|
|
24. What enzymes are responsible for phosphorylation and dephosphorylation? Does phosphorylation always lead to activation and dephosphorylation always lead to inactivation?
|
Phosphorylation occurs via kinases
Dephosphorylation occurs via phosphatases No, phosphorylation and dephosphorylation can lead to either activation or inactivation |
|
|
25. What are second messengers and what are they used for?
|
Second messengers are small intracellular mediators
They are used in various signaling pathways and responses; they can be sequestered, diffusion restricted, or bound to facilitate signal transduction |
|
|
26. What are five common second messengers?
|
Cyclic AMP, cyclic GMP, IP3, Ca2+, and diacylglycerol
|
|
|
27. Where does cytosolic calcium come from? If calcium participates in so many different signaling events, how does the cell ensure inappropriate calcium-mediated signaling events do not occur? |
cytosolic calcium comes from the endoplasmic reticulum
Calcium is sequestered by the ER by Ca2+ pumps, the mitochondria by active Ca2+ transport, and Ca2+ binding molecules |
|
|
28. How does calmodulin function as a relay? Explain how calmodulin activates CaM kinase. |
The presence of Ca2+ activates calmodulin, which then relays the Ca2+ signal to CaM kinase. When calmodulin is allosterically activated by Ca2+, it can then bind to CaM kinase, activating CaM kinase. |
|
|
29. Do cells usually achieve target mechanisms in response to just one type of signaling molecule? |
Many signaling molecules are required to achieve target mechanisms; they act in combination with one another to elicit a particular response.
|
