BS 161: Chapter 9 Review questions with verified
answers
*Because the G-protein can shut itself off, the whole system can be shut down
quickly when the extracellular signal molecule is no longer present.* Ans✓✓✓ *If
you inhibit the GTPase function of the G-protein, it can no longer be shut off, the
G- protein is permanently activated!!*
1. Reception Ans✓✓✓ In *reception*, a chemical signal binds to a cellular
protein, typically at the target cell's surface or inside the cell. *Signal binding to
the receptor effects a structural change that activates the receptor.*
2. Tranduction Ans✓✓✓ In transduction, the structural change in the receptor,
initiates the process of transduction.
Transduction may occur in a single step but more often triggers a series of
changes in a series of different molecules along a signal transduction pathway.
The molecules in the pathway are called *relay molecules*.
3 main Molecular Switches (on/off) in cells Ans✓✓✓ 1. Ligand binding (allostery)
2. Protein phosphorylation
3. GTP binging and Hydrolysis
3. Response Ans✓✓✓ In response, the transduced signal triggers a specific
cellular activity.
, 4. Termination Ans✓✓✓ In Termination, the response terminates (all molecular
switches must be reset).
An individual tyrosine-kinase receptor consists on three parts: Ans✓✓✓ an
extracellular signal-molecule-binding site, a single α helix spanning the
membrane, and an intracellular kinase domain (kinases can covalently link
phosphates to other molecules). In the case of Receptor tyrosine kinases, the
enzyme specifically targets tyrosine amino acids in proteins.
Cancer Ans✓✓✓ Cancer is a set of diseases in which cells escape the control
mechanisms that normally regulate cell growth and division.
Cancer results from..... Ans✓✓✓ genetic changes that affect sell cycle control
Cell communication Ans✓✓✓ Cell-to-cell communication is absolutely essential
for multicellular organisms. Cells must communicate to coordinate their activities.
Communication between cells is also important for unicellular organisms.
Cells most often communicate by..... Ans✓✓✓ Cells most often communicate by
chemical signals, although signals may also take other forms (for example
mechanical (hearing) and voltage (membrane potential change!). `
Dephosphorylation Ans✓✓✓ By dephosphorylating and thus inactivating protein
kinases, phosphatases provide the mechanism for turning off the signal
transduction pathway when the initial signal is no longer present.
G-protein acts as an on-off switch Ans✓✓✓ If GDP is bound to the G protein, the
G protein is inactive.
answers
*Because the G-protein can shut itself off, the whole system can be shut down
quickly when the extracellular signal molecule is no longer present.* Ans✓✓✓ *If
you inhibit the GTPase function of the G-protein, it can no longer be shut off, the
G- protein is permanently activated!!*
1. Reception Ans✓✓✓ In *reception*, a chemical signal binds to a cellular
protein, typically at the target cell's surface or inside the cell. *Signal binding to
the receptor effects a structural change that activates the receptor.*
2. Tranduction Ans✓✓✓ In transduction, the structural change in the receptor,
initiates the process of transduction.
Transduction may occur in a single step but more often triggers a series of
changes in a series of different molecules along a signal transduction pathway.
The molecules in the pathway are called *relay molecules*.
3 main Molecular Switches (on/off) in cells Ans✓✓✓ 1. Ligand binding (allostery)
2. Protein phosphorylation
3. GTP binging and Hydrolysis
3. Response Ans✓✓✓ In response, the transduced signal triggers a specific
cellular activity.
, 4. Termination Ans✓✓✓ In Termination, the response terminates (all molecular
switches must be reset).
An individual tyrosine-kinase receptor consists on three parts: Ans✓✓✓ an
extracellular signal-molecule-binding site, a single α helix spanning the
membrane, and an intracellular kinase domain (kinases can covalently link
phosphates to other molecules). In the case of Receptor tyrosine kinases, the
enzyme specifically targets tyrosine amino acids in proteins.
Cancer Ans✓✓✓ Cancer is a set of diseases in which cells escape the control
mechanisms that normally regulate cell growth and division.
Cancer results from..... Ans✓✓✓ genetic changes that affect sell cycle control
Cell communication Ans✓✓✓ Cell-to-cell communication is absolutely essential
for multicellular organisms. Cells must communicate to coordinate their activities.
Communication between cells is also important for unicellular organisms.
Cells most often communicate by..... Ans✓✓✓ Cells most often communicate by
chemical signals, although signals may also take other forms (for example
mechanical (hearing) and voltage (membrane potential change!). `
Dephosphorylation Ans✓✓✓ By dephosphorylating and thus inactivating protein
kinases, phosphatases provide the mechanism for turning off the signal
transduction pathway when the initial signal is no longer present.
G-protein acts as an on-off switch Ans✓✓✓ If GDP is bound to the G protein, the
G protein is inactive.
