AP Biology Chapter 11 Flashcards

Questions and Answers

What is a signal transduction pathway?

Process by which a signal on a cell's surface is converted to a specific cellular response in a series of steps.

How does yeast mating serve as an example of a signal transduction pathway?

Alpha yeast sends alpha signals that A yeast receives. A yeast sends A signals that only alpha can receive. The respective signals are then transduced and a response is carried out (mating).

What is paracrine signaling?

Secreting cells send regulators to target cells and to all cells in the vicinity. Examples are animal cells and growth hormones.

What is synaptic signaling?

Electrical signals trigger chemical signals that affect only the target cell. Signup and view all the answers

How does a hormone qualify as a long-distance signaling example?

Hormones can travel to any part of the body via the circulatory system. Signup and view all the answers

What is reception in cell signaling?

Detection of a signaling molecule. Signup and view all the answers

What is transduction in cell signaling?

Signal converted to a form that can bring about a specific cellular response. Signup and view all the answers

What is a response in cell signaling?

Transduced signal triggers some sort of cellular response. Signup and view all the answers

What is a ligand?

A molecule that specifically binds to another, usually bigger molecule. Signup and view all the answers

What activates a G protein?

Signaling protein activates receptor, receptor changes shape, G protein binds to enzyme. Signup and view all the answers

Why is the fact that a G protein is also a GTPase enzyme important?

It stops the signal and converts GTP back to GDP. Signup and view all the answers

What does a kinase enzyme do?

Catalyzes transfer of phosphate groups. Signup and view all the answers

How does tyrosine kinase function in the membrane receptor?

It allows for the activation of many signal transduction pathways. Signup and view all the answers

What is a key difference between receptor kinases and G protein-coupled receptors?

Receptor kinases can activate many signal transduction pathways compared to just one that G protein-coupled receptors can. Signup and view all the answers

Each activated protein in tyrosine kinase triggers a signal pathway leading to a response.

transduction...cellular Signup and view all the answers

In what body system are ligand-gated ion channels and voltage-gated ion channels of particular importance?

Nervous system. Signup and view all the answers

Intracellular receptors are found in the or of the cell, where they bond to chemical messengers that are _ or very small, like nitric acid.

cytoplasm...nucleus...hydrophobic Signup and view all the answers

What are transcription factors?

They are molecule complexes that control which genes are turned on and transcribed to mRNA. Signup and view all the answers

What are two benefits of multistep pathways?

Amplification of signal and better regulation. Signup and view all the answers

What is the role of protein kinase?

Transfer phosphate groups from ATP to proteins. Signup and view all the answers

What is the role of protein phosphatases?

Remove phosphate groups from proteins. Signup and view all the answers

What is the difference between a first messenger and a second messenger?

First messenger is the ligand, second messenger is any small, non-protein components of a signal transduction pathway. Signup and view all the answers

What is the role of cAMP?

cAMP activates protein kinase A, which causes a cellular response. Signup and view all the answers

Explain the mechanism of disease in cholera.

G protein cannot hydrolyze GTP to GDP, enzyme that the G protein activates is always on, cAMP constantly is being produced, salt is constantly released as a cellular response, leading to diarrhea due to osmosis. Signup and view all the answers

List three pathways often induced by calcium ions.

Pathway via mitochondria, ER, and plasma membrane. Signup and view all the answers

What happens to the cytoplasmic concentration of calcium when it is used as a second messenger?

It increases. Signup and view all the answers

When cell signaling causes a response in the nucleus, what normally happens?

Proteins become transcription factors, certain genes are chosen, these are then transcribed. Signup and view all the answers

When cell signaling causes a response in the cytoplasm, what normally happens?

Regulation of activity of proteins. Signup and view all the answers

How do scaffolding proteins enhance a cellular response?

Enhancement of speed and accuracy because the rate of response is no longer limited by the rate of diffusion. Signup and view all the answers

What specifically happens to a cell during the process of apoptosis?

DNA chopped up, cell shrinks, lobes up, vesicles form, digestion by scavenger cells. Signup and view all the answers

Give one example of a signal for apoptosis coming from outside the cell, and two from inside the cell.

Out: death signaling molecule reacts with protein and activates Ced-9. IN1: leaking form mitochondria. IN2: ER due to excessive misfolding of proteins. Signup and view all the answers

Study Notes

Signal Transduction Pathways

Signal transduction pathways convert external signals into specific cellular responses through a series of steps.
Yeast mating exemplifies this by using alpha and A signals, leading to mating responses upon transduction.

Types of Signaling

Paracrine signaling: Local regulators secreted by cells affect nearby target cells; common in growth factor signaling in animals.
Synaptic signaling: Electrical signals trigger the release of neurotransmitters to specifically affect target cells, ensuring precise communication.

Hormone Signaling

Hormones serve as long-distance signals that circulate throughout the body via the bloodstream, reaching various target cells.

Basic Concepts of Cell Signaling

Reception: Involves detecting signaling molecules by target cells.
Transduction: Converts signals into forms that elicit specific cellular responses.
Response: The final outcome from the transduced signal, resulting in specific cellular activities.

Molecular Components

Ligands: Molecules that specifically bind to larger molecules (receptors).
G proteins: Activated by signaling proteins, they undergo shape changes and bind to enzymes to propagate signals.
GTPase activity: A G protein’s ability to hydrolyze GTP to GDP halts signal transmission.

Enzymatic Roles

Kinase enzymes: Catalyze phosphorylation, transferring phosphate groups to proteins, thereby altering their function.
Tyrosine kinase: Activates various signal transduction pathways by modifying receptor configuration.
Protein phosphatases: Remove phosphate groups from proteins, reversing the effects of kinases.

Signaling Pathways Comparison

Receptor kinases can activate multiple signal transduction pathways, unlike G protein-coupled receptors which typically activate a single pathway.

Cellular Mechanisms

Ligand-gated and voltage-gated ion channels play critical roles in the nervous system.
Intracellular receptors, found in the cytoplasm or nucleus, bind hydrophobic chemical messengers like nitric oxide.

Transcription Factors and Cellular Regulation

Transcription factors are protein complexes that regulate gene expression by controlling mRNA transcription in response to signals.

Advantages of Multistep Pathways

Multistep pathways amplify signals and provide enhanced regulation of cellular responses.

Secondary Messengers

cAMP: A secondary messenger that activates protein kinase A, promoting cellular responses.
Calcium ions: Serve as crucial secondary messengers, their concentrations increase to facilitate various signaling pathways.

Cellular Responses to Signaling

In the nucleus, signaling typically results in the activation of transcription factors affecting gene expression.
In the cytoplasm, signaling leads to the regulation of protein activity.

Scaffolding Proteins

Scaffolding proteins improve the speed and accuracy of cellular responses by localizing signaling molecules and enhancing interactions.

Apoptosis Process

Apoptosis features DNA fragmentation, cell shrinkage, membrane lobing, vesicle formation, and subsequent digestion by scavenger cells.

Apoptosis Signals

External signals: Death signaling molecules interact with Ced-9 to trigger apoptosis.
Internal signals: Include mitochondrial leakage and stress from misfolded proteins in the endoplasmic reticulum.

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Explore key concepts of 'Cell Communication' in AP Biology with these flashcards. Understand the processes involved in signal transduction pathways and their examples, such as yeast mating. Perfect for reinforcing your knowledge before exams.