Cell Communication and Signal Transduction Pathway

These flashcards cover key concepts from the lecture on Cell Communication and Signal Transduction Pathways, focusing on mechanisms of signaling, prokaryotic and eukaryotic communication, apoptosis, and cell cycle regulation.

What are the general steps in signal transduction?

1. Synthesis of signaling molecule 2. Release of signaling molecule by the signaling cell 3. Transport of signal to target cell 4. Interaction of signal with target cell 5. Change in cell behavior

Define quorum sensing in bacteria.

Quorum sensing is a process where bacteria detect their population density through signal molecules known as autoinducers to coordinate behavior.

What are the components of the 2-component signaling system in bacteria?

1. Sensor (Histidine protein kinase) 2. Effector (Response regulator - Aspartic acid protein kinase)

What are the two types of communication in prokaryotic cells?

1. Quorum sensing 2. 2-component signaling systems

What triggers the gene expression in quorum sensing?

When the concentration of signaling autoinducers (AI) reaches a certain threshold, triggering collective gene activation.

What is the role of G-proteins in signal transduction?

G-proteins act as molecular switches that are activated by exchanging GDP for GTP, activating downstream signaling pathways.

What is the difference between endocrine and paracrine signaling?

Endocrine signaling involves signaling molecules that travel long distances via blood, while paracrine signaling involves localized signaling between adjacent cells.

What is apoptosis?

Apoptosis is a signaling pathway leading to programmed cell death, crucial for normal development and response to cellular damage.

How do receptor tyrosine kinases (RTKs) function?

RTKs undergo autophosphorylation upon ligand binding, leading to the activation of downstream signaling pathways.

What is the role of cyclins in cell cycle regulation?

Cyclins are proteins that activate cyclin-dependent kinases (CDKs), which regulate various phases of the cell cycle.

What happens during the G1 phase of the cell cycle?

The cell grows and carries out normal metabolic functions while duplicating its organelles.

What is the purpose of signaling cascades in cells?

To amplify the signal and produce a coordinated cellular response through a series of protein activations, often involving phosphorylation.

What are secondary messengers in cell signaling?

Small molecules, such as cAMP or calcium ions, that relay signals from cell surface receptors to target molecules inside the cell.

In cellular signaling, what does 'crosstalk' refer to?

The interaction between different signaling pathways that can modify the output of individual signals.

What are the characteristics of slow response signaling in eukaryotic cells?

Mediated by steroid hormones, involves gene transcription, and has a longer half-life and slower degradation.

How does the ubiquitin-proteasome pathway regulate the cell cycle?

By targeting specific cyclins and proteins for degradation, thereby regulating cell cycle progression.