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Chapter 11 HW
General Biology I (BIO-181)
Grand Canyon University
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Chapter 11-
Definition matching: (a) Mating factors 9 (1) Signaling molecule (b) Local regulators 7 (2) Signaling molecule for nerve cells. (c) Paracrine signaling 11 (3) Cell death. (d) Synaptic signaling 4 (4) Messenger molecules travel a short distance. (e) Endocrine/Hormonal signaling 8 (5) Ligand. (f) Ligand 1 (6) cyclic AMP (g) Neurotransmitter 2 (7) Signal transmission within the nervous system (h) Second messengers 6 (8) Signal molecules travel through the circulatory system. (i) Transcription factor 10 (9) Signals that cause 2 cells to fuse together. (j) Scaffolding protein 12 (10) Makes RNA using DNA as a template. (k) Apoptosis 3 (11) Signal transmission using local regulators. (l) First messengers 5 (12) A protein that holds relay proteins close together.
Describe the process of apoptosis. Apoptosis is cell suicide. In this process, the cell shrinks and becomes lobed, and the cell’s components are packaged in vesicles that are then engulfed by specific scavenger cells. The deactivation causes Ced-4 to activate Ced-3 which eventually activates nucleases and the other proteases that carry out the cell disassembly.
What occurs during phosphorylation? It is a process that adds a phosphate group to ana existing molecule to prepare it to change or do work.
What are second messengers? They are intracellular signaling molecules that are released by the cell in response to extracellular signaling molecules. Second messengers are water soluble and small.
List and describe the three levels of cell signaling. Reception: Chemical signals bind to the receptor protein on the cell’s surface Transduction: the signaling molecule binds to the receptor protein and changes the shape of the protein Response: The signal triggers a specific cellular response.
How do hormones illicit an intracellular response? At the target cell, the hormones are released from the carrier protein and diffuse across the lipid bilayer of the plasma membrane of the target cells. They then adhere to intracellular receptors residing in the cytoplasm or in the nucleus.
- Determine if the following terms are referencing local or long distance signaling.
Hormone Long distance
Paracrine Local
Synaptic Local
Endocrine Long distance Secretory Cell Long distance Target cell Long distance
Local regulator Local Neurotransmitter Local Autocrine Local
- What are the 3 steps of a signal transduction pathway?
Reception: A chemical message that binds to a receptor protein on the cell surface. Transduction: Signal molecule binds to receptor producing conformational changes of the receptor protein; receptor activation starts a cascade of reactions known as a signal transduction pathway.
Reception Transduction Response Receptor Cellular Response Signal-transduction Signal pathway molecule
Response: Response of the transduction pathway; could be gene regulation, enzyme activation, or cytoskeleton rearrangement.
- Based on the image shown answer the following questions. (a) What is the role of the G-Protein Coupled Receptor?
They act like an inbox for messages in the form of light energy, peptides, lipids, sugars, and proteins.
(b) What is the role of the G-Protein?
They regulate metabolic enzymes, ion channels, transporter proteins, and other parts of the cell that regulate systemic functions.
(c) What is the role of the GTP?
It is an energy-rich molecule, and it facilitates binding of protein factors either to tRNA or to the ribosome.
(d) What is the role of the Adenylyl Cyclase?
It synthesizes cyclic AMP which is the key messenger that regulates diverse physiological responses including sugar and lipid metabolism, olfaction, and cell growth and differentiation.
(e) What is the role of the cAMP and why is it considered a second messenger? cAMP serves as an intracellular second messenger for numerous extracellular signals in the nervous system. It facilitates and promotes the mobilization of glucose and fatty acid reserves.
(f) What is the role of the Protein Kinase A? What do all Kinases do? What do all Phosphatases do? It acts to phosphorylate many enzymes important to metabolism. It also phosphorylates in both the cytoplasm and nucleus and changes the activity of many important molecules.
(g) What is the overall goal of this pathway?
The overall goal of this is to make GMP.
- The second messenger that causes calcium ion to be released from intracellular stores is inositol triphosphate (IP3).
A. A drug has been made that binds to and activates the receptor. This drug is a(n) agonist.
- The GnRH receptor is a G protein coupled receptor that activates an IP 3 , DAG second messenger signal transduction pathway when stimulated by GnRH. List the intracellular steps, including specific molecules that are activated by GnRH binding to its receptor.
The GnRH neurons are regulated by many different afferent neurons, using several different transmitters. For instance, dopamine appears to stimulate LH release in estrogen-progesterone-primed females; dopamine my inhibit LH release in ovariectomized females.
- Epinephrine, when it binds to 2 receptors, initiates a cAMP second messenger system for transduction of the signal within the activated cell. (CRITICAL THINKING) What class of receptor is a 2 receptor? (choose and circle your answer below) A. Ion Gated Channel B. Receptor Tyrosine Kinase Pathway
C. G Protein Coupled Receptor
- After epinephrine binds to the receptor, what steps occur to result in an increase in cAMP?
After the binding of epinephrine there is an elevation in the intracellular level of cAMP. The increase of cAMP results from activation of adenylyl cyclase, which converts ATP to cAMP and pyrophosphate (PPi).
- An increase in an epinephrine ligand would cause (choose and circle your answer below)
A. increase in epinephrine B. increase in cAMP
C. decrease in cAMP
Answer these questions: Cell Communication
Draw a G-protein receptor and diagram its signaling cascade.
Draw a Tyrosine-kinase receptor and diagram its signaling cascade.
Draw a ligand-gated ion channel and diagram its signaling cascade.
What types of molecules bind to intracellular receptors?
Intracellular receptors require ligands that are membrane permeable and include receptors
for steroids. Small hydrophobic molecules bind to them.
- When testosterone binds to a receptor in the cytoplasm, the complex goes into the nucleus of the cell and then does what? Sketch this intracellular receptor signaling cascade.
It turns on the genes.
Chapter 11 HW
Course: General Biology I (BIO-181)
University: Grand Canyon University
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