cell signaling introduction map 1

What is the fundamental purpose of cell signaling in multicellular organisms?

Communication while in unicellular is survival

does cell signaling differ between normal cells and cancer cells?
A:

In cancer is abnormal and uncontrolled

A:

What are the sequential steps of signal transduction from signal production to termination?

• Signal synthesis

• Signal release

• Signal transport

• Signal binding to receptor

• Intracellular signaling cascade

• Cellular response (short- or long-term)

• Feedback regulation

• Signal termination (switch-of

What is the difference between short-term and long-term cellular responses?

• Short-term responses involve rapid changes in existing proteins (e.g. enzyme activation).

• Long-term responses involve changes in gene expression, requiring transcription and translation.

2 type of cell sigaling

1. Direct cell-cell signaling

2. Signaling via secreted molecules

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What are the mechanisms of direct cell-cell signaling?

• Contact-dependent signaling via membrane proteins (e.g. cadherins, integrins)

• Gap junctions, allowing small molecules to pass directly between adjacent cells

paracrine, endocrine, and autocrine signaling?

• Paracrine: acts on nearby cells as neurotransmitters

• Endocrine: acts on distant cells via bloodstream hormons

• Autocrine: cell signals itself LYMPHOCYTE T

How does the stability of a signaling molecule influence its signaling range?

Is you are stable you can go along long ditnace as hormons

If you are not stable you act local as NITRIC OXIDE

What is the role of receptors in signal transduction?

Receptors act as signal transducers, binding ligands with high affinity and converting extracellular signals into intracellular responses.

Why do non-target cells not respond to a signal?

Because they lack the specific receptor required to detect and transduce that signal.

What are the four main mechanisms by which intracellular signals are transmitted?

• Protein–protein interactions

• Binding of second messengers

• Covalent modifications (e.g. phosphorylation)

• GTP/GDP binding (molecular switches)

does phosphorylation regulate protein activity?

Phosphorylation can either activate or inhibit a protein depending on the context and target site.

Q: Why can two inhibitory signals produce a positive effect in signaling pathways

• - - +

What is signal amplification and why is it important?

single receptor activation can activate many downstream molecules, greatly increasing the strength of the signal and allowing a small stimulus to produce a large response.

What determines the specificity of a signaling response?

• Type and number of receptors

• Intracellular signaling proteins

• Available effector proteins

What is signal integration?

The process by which multiple signaling pathways interact to produce a combined cellular response.

How do cells avoid random activation due to cytoplasmic noise?

• High specificity binding

• Threshold activation

• Redundant (backup) pathways

Q: What is the difference between positive and negative feedback in signaling?

• Positive feedback amplifies the response and can create all-or-none behavior AMPLIFICATION

• Negative feedback limits and stabilizes the response making it less sensitive and REGULATION!

What is signaling crosstalk?

Interaction between different signaling pathways, allowing coordination and fine-tuning of cellular responses.

What roles do adaptor, scaffold, and docking proteins play in signaling?

• Adaptor proteins: connect signaling proteins

• Docking proteins: increase binding sites

• Scaffold proteins: organize signaling complexes for efficiency allow signaling

are modular interaction domains and why are they important?

They are specialized protein domains that mediate specific interactions, ensuring correct assembly of signaling complexes.

Examples:

PH domain → binds membrane lipids

SH2/PTB → bind phosphorylated tyrosines

SH3 → bind proline-rich regions

PH domain

Membrane lipids binds

SH2/PTB

bind phosphorylated tyrosines

SH3

bind proline-rich regions