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BIOD 101 Module 5 (EXAM)
ACTUAL SOLUTION
Which of the following signaling types is used to transmit ligands to their target cells over long distances, using the circulatory system as a transport medium?
- Autocrine signaling
- Endocrine signaling
- Direct cell-to-cell signaling
- Paracrine signaling
- Synaptic signaling - ans-Endocrine signaling.
Explain why a steroid hormone would require a carrier protein to transport it through the bloodstream. - ans-Steroid hormones are hydrophobic. They would require a carrier protein to carry it through the blood because it is considered hydrophilic. Each of the following is true regarding cellular receptors except:
- Receptors in each family are classified by their location in the body.
- Most receptors are located on the outside of a cell, anchored in the plasma membrane.
- Cell surface receptors contain an extracellular region, intracellular region, and a hydrophobic region in the plasma membrane.
- Intracellular receptors are located in the cell's cytoplasm. - ans- Receptors in each family are classified by their location in the body. List TWO specific examples of cellular ligands. - ans-Hormones, peptides, sugars, and other hydrophobic molecules.
For most biological processes, a typical response would be the release of ___________ of molecules every ___________ that binds. - ans-1. Millions
- Ligand What role do the ligands involved in endocrine signaling serve in the body. - ans-Hormones are the ligands involved in endocrine signaling. They regulate homeostatic mechanisms e.g., blood pressure and energy metabolism. Which of the following best describes calcium's role as a second messenger?
- It activates protein kinase A.
- It activates protein kinase C.
- It binds to proteins to change their shape and function.
- All of the above. - ans-It binds to proteins to change their shape and function. True or False. If false, explain why it is false.
A ligand can bind to any cell in the body as long as the receptor is free to bind. - ans-False. Ligands have specific receptors they must bind to. If there was no specificity, the ligands would be binding to every single target cell it touches; therefore, resulting in changes throughout the whole body. Which of the following is/are true of RTKs? (Select all that apply).
- They are a family of enzyme-linked receptor molecules.
- They have an extracellular region only.
- They transfer a phosphate group to the amino acid tyrosine on a target protein. -None of the above are true. - ans--They are a family of enzyme-linked receptors molecules. -They transfer a phosphate group to the amino acid tyrosine on a target protein. Explain the relationship between cancer development and apoptosis. - ans-Cells that undergo apoptosis typically have something wrong with
-Endocrine signaling = Involved in regulating homeostatic mechanisms. -Direct cell-to-cell signaling = Gap junctions are associated with this type of signaling. -Paracrine signaling = Involved in the secretion of growth factors. -Synaptic signaling = Neurons use this type of signaling. Briefly describe the process of phosphorylation. - ans-Phosphorylation is the reversible process of adding a phosphate to one or more sites on a molecule to activate it (turn it "on") or inactivate it (turn it "off"). Fill in the Blank: G proteins share the broad function of ___________ GTP to GDP. - ans- Hydrolyzing (breaking down). What role do ligands play in the alteration of gene expression? - ans- Ligands may alter the processes of transcription and/or translation resulting in changes to gene expression.
Fill in the Blank in the following paragraph describing the signaling pathway. Signaling begins when an extracellular ___________ binds to a receptor anchored within the plasma membrane. Relay molecules and scaffolding proteins ___________ the signal to activate a cellular response. - ans-1. Ligands
- Transduce Once inside the intestinal walls, what does v. Cholera bacterium produce that bind to a GPCR, causing the target cell to be permanently activated? - ans-The V. Chlolera bacterium produces an EXOTOXIN that binds to the GPCR, preventing it from hydrolyzing GTP to GDP. When a signaling ligand binds to the extracellular binding region of an RTK, what happens THIRD?
- Dimerization of individual monomers.
- Inactive relay proteins become activated.
- Auto-phosphorylation. - ans-Inactive relay protein become activated. The target cell is considered:
- Ligand binding is reversible. - ans-- They allow the passage of ions and acts as a receptor.
- The binding of a ligand causes the channels to open.
- The lumen of the channel is hydrophilic.
- Ligand binding is reversible. Explain how a cellular signaling pathway is terminated. - ans-Ligands binding to their receptors is a reversible phenomenon. As the concentration of signaling ligands decreases, fewer molecules bind to the receptors to initiate a transduction pathway and response. When the receptors are not being activated, the cell returns to a resting, inactive state. Which of the following is FALSE regarding scaffolding proteins?
- They physically support proteins involved in signaling pathways.
- They improve efficiency in the transduction.
- They add phosphates to target cell receptor sites. - ans-They add phosphates to target cell receptor sites. Ligand-gated ion channels are the main receptor type for what cells in the human body? - ans-Neurons.
