10 ASP Biology term 3 collection

Epinephrine is a protein hormone found in many animals. Epinephrine stimulates a signaling pathway that results in the breakdown of glycogen to glucose in the liver cells. Which of the following describes the initial steps in the process whereby epinephrine stimulates glycogen breakdown?

(A) Epinephrine binds to a cell-surface receptor, the activated receptor stimulates production of the second messenger, cAMP

The mechanism of action of many common medications involves interfering with the normal pathways that cells use to respond to hormone signals. Which of the following best describes a drug interaction that directly interferes with a signal transduction pathway?

(B) A medication enters the target cell and inhibits an enzyme that normally synthesizes a second messenger

Which of the following describes a metabolic consequence of a shortage of oxygen in muscle cells?

(C) A buildup of lactic acid in the muscle tissue due to fermentation

One approach to treating patients with pancreatic cancer and other cancers in which Hedgehog protein is detected is to modify the hedgehog signaling pathway. Which of the following is the most useful approach?

(C) Treating patients with a membrane-soluble compound that can bind to Smo and block its activity.

At puberty, an adolescent female body changes in both structure and function of several organ systems, primarily under the influence of changing concentrations of estrogen and other steroid hormones. How can one hormone, such as estrogen, mediate so many effects?

(D) Estrogen binds to specific receptors inside many kinds of cells, each of which have different responses to its binding

Which of the following is the best explanation for the fact that most transduction pathways have multiple steps?

(D) Multiple steps provide for greater possible amplification of a signal.

Ligands bind reversibly to their receptors. Select the statements that describe what would happen if ligands bound irreversibly with their receptors.

-The cell cannot receive new signals. -Termination of the signal cannot occur.

The diagram below shows a phosphorylation cascade. Identify the proteins involved in the phosphorylation cascade. Top

1. (Yellow) - Signaling molecule 2. (Red) - Active kinase 3. (Gray) - Inactive kinase 4. (Blue) - Phosphatase 5. (Pink) - Activated affector protein Bottom

briefly explain the role of each numbered step in regulating target gene expression

1. The hormone or ligand binds to the receptor trigger a signal. 2. An intracellular cascade then sends the signal to the nucleus from the plasma membrane. 3. The transcription of the target genes are also triggered.

What happens in the response phase of cell signaling when protein signal molecules are present?

A cell reacts to the message from signal molecules by initiating changes in shape, activity, or behavior.

At any given time, there is an array of signaling molecules in a cell's environment. How does a cell "know" which signaling molecules to respond to?

A cell responds to a signaling molecule only if the cell has the appropriate receptor.

Which of the following best describes a ligand?

A small molecule that influences a larger molecule when the two bind.

researches conducted a study to investigate the effect of exercise on the release or prolactin into the blood. The researchers measured the concentration of prolactin in the blood of eight adult males before (T=0 hour) and after one hour (T= 1 hour) of vigorous exercise. As a control, the researchers measured the concentration of blood prolactin in the same group of individuals at the same times of day one week later, but without having them exercise The results are shown in figure 1.

A. The exercise treatment acts as a control group to see what normal levels of blood prolactin are but an without-exercise control group, it will remove time as a variable. B. The prolactin release does not change after exercise because t=0 hour and t=1 hour.

Smell perception in mammals involves the interactions of airborne odorant molecules from the environment with receptor proteins on the olfactory neurons in the nasal cavity. The binding of odorant molecules to the receptor proteins triggers action potentials in the olfactory neurons and results in transmission of information to the brain. Mammalian genomes typically have approximately 1,000 functional odorant-receptor genes, each encoding a unique odorant receptor.

A. When a charge reaches a synapse, it causes the gated calcium proteins to open which allows calcium to come into the synapse. When calcium enters it stimulates the vesicles around the neurotransmitters to release (exocytosis) the neurotransmitters into the synapse. The neurotransmitters then bind to the receptors of sodium channels. When the sodium rushes in it cause the formation of the action potential which sends the information to your brain. b. A limited number of odorant receptor genes can lead to the perception of thousands of odors because alternate splicing through co-transcriptional modification. Once an mRNA is transcribed a, spliceosome removes the non-coding intros and splices together the rest of the exon. However they can be placed into multiple combinations of odorant proteins.

The epinephrine signaling pathway plays a role in regulating glucose homeostasis in muscle cells. The signaling pathway is activated by the binding of epinephrine to the beta-2 adrenergic receptor. A simplified model of the epinephrine signaling pathway is represented in Figure 1. Figure 1. A simplified model of the epinephrine signaling pathway in muscle cells A researcher claims that the epinephrine signaling pathway controls a catabolic process in muscle cells. Which of the following statements best helps justify the researcher's claim?

Glycogen phosphorylase catalyzes the conversion of glycogen to glucose-1-phosphate.

he epinephrine signaling pathway plays a role in regulating glucose homeostasis in muscle cells. The signaling pathway is activated by the binding of epinephrine to the beta-2 adrenergic receptor. A simplified model of the epinephrine signaling pathway is represented in Figure 1. Figure 1. A simplified model of the epinephrine signaling pathway in muscle cells Based on Figure 1, which of the following statements best describes the epinephrine signaling pathway?

In involves enzymes activating other enzymes.

The epinephrine signaling pathway plays a role in regulating glucose homeostasis in muscle cells. The signaling pathway is activated by the binding of epinephrine to the beta-2 adrenergic receptor. A simplified model of the epinephrine signaling pathway is represented in Figure 1. Figure 1. A simplified model of the epinephrine signaling pathway in muscle cells Which of the following statements best describes the role of adenylyl cyclase in the epinephrine signaling pathway?

It accelerates the production of a second messenger.

In a certain signal transduction pathway, the binding of an extracellular molecule to a cell-surface protein results in a rapid increase in the concentration of cyclic AMP inside the cell. The cyclic AMP binds to and activates cytosolic enzymes that then activate other enzymes in the cell. Which of the following statements best describes the role of cyclic AMP in the signal transduction pathway?

It acts as a second messenger that helps relay and amplify the signal within the cell.

Which of the following describes the way in which phosphorylation directly contributes to signal transduction?

Phosphorylation changes the shape of the protein to which it is added, allowing the protein to interact with new binding partners.

Which of the following are mechanisms that a cell uses to relay an external signal during signal transduction?

Protein dephosphorylation AND second messengers

Classify the following statements as describing a protein kinase of a protein phosphatase. Protein kinase: -Phosphorylates a protein -Binds adenosine triphosphate (ATP)

Protein phosphatase: -Removes a phosphate group from a protein -Releases inorganic phosphate

The process of cell signaling involves three phases: the reception phase, the transduction phase, and the response phase. What happens in each phase? Place three of the four statements below.

Reception: Specialized cell surface proteins bind to specific protein signal molecules outside the cell. Transduction: Signal molecules induce a change in membrane proteins that activates other proteins within the cell. Response: A cell reacts to the message from signal molecules by initiating changes in shape, activity, or behavior.

How does a signaling molecule present in low concentrations cause a significant response in the cell?

Signal amplification

What happens in the transduction phase of cell signaling when protein signal molecules are present?

Signal molecules induce a change in membrane proteins that activates other proteins within the cell.

What happens in the reception phase of cell signaling when protein signal molecules are present?

Specialized cell surface proteins bind to specific protein signal molecules outside the cell.

The epinephrine signaling pathway plays a role in regulating glucose homeostasis in muscle cells. The signaling pathway is activated by the binding of epinephrine to the beta-2 adrenergic receptor. A simplified model of the epinephrine signaling pathway is represented in Figure 1. Figure 1. A simplified model of the epinephrine signaling pathway in muscle cells Which of the following outcomes will most likely result from the irreversible binding of GDP to the G protein?

The intracellular concentration of glycogen will increase.

The membranes of the rough endoplasmic reticulum have a very large surface area. In one of two sentences, describe how a large surface area aids the activities of this structure.

The large surface area of the cell aids the activities of this structure because it allows more space for embedded ribosomes and the production and modification of proteins.

How can cells of different tissues respond differently to the same signal molecule?

Variations in the set of proteins that the cell possesses

The picture above represents the investigation that we performed in lab. Recall the size of each cube being approximately; 1cm3, 8cm3 and 27cm3. The size of a human cell is approximately a 0.01mm (a) Using the formulas from the lab activity, calculate the surface to volume ratio of the human cell. (Surface Area of Cube) = (length) x (width) x (# of sides)(Volume) = (length) x (width) x (height)(Surface Area to Volume Ratio) = (Surface Area/Volume) (b) Assuming the same conditions as you had in the lab, after one minute, predict whether you expect the extent of diffusion in a human cell to be greater, lesser or the same as the smallest agar cube?

a. 6,000b.I predict the extent of diffusion in a human cell to be greater because human cells are much smaller than agar cubes.

Figure 1 shows a model of a signal transduction cascade, initiated by the binding of a ligand to the transmembrane receptor protein A. Figure 1. Model of signal transduction cascade incorporating protein A A DNA mutation changes the shape of the extracellular domain of transmembrane receptor protein A produced by the cell. Which of the following predictions is the most likely consequence of the mutation?

the molecule that normally binds to protein AA will no longer attach, deactivating the cellular response.