Day 3 - Part 1

What are the three core steps of a signaling pathway

Signal generation signal reception and signal transduction followed by cellular response

What happens during signal generation

A ligand is produced and released by a cell

What are examples of signaling molecules

Growth factors hormones neurotransmitters and gases

What happens during signal reception

A ligand binds to a receptor

Where can receptors be located

On the cell surface or inside the cell

What type of signals use intracellular receptors

Lipid-soluble signals like steroids

What happens during signal transduction

The receptor activates intracellular signaling molecules

How is the signal relayed inside the cell

Through protein interactions phosphorylation cascades and second messengers

What are possible cellular responses to signaling

Gene expression cell division survival metabolism and movement

What is the key idea about signaling pathways

They are modular and layered systems

What does modular mean in signaling pathways

Different components can be combined in different ways

What does layered mean in signaling pathways

Each step adds control amplification and integration

What are the main chemical types of signaling molecules

Proteins steroids nucleic acids fatty acids and gases

What is autocrine signaling

A cell signals to itself

What is paracrine signaling

A cell signals to nearby cells

What is endocrine signaling

Signals travel long distances through the bloodstream

What is juxtacrine signaling

Signaling requires direct cell to cell contact

How do hydrophobic signaling molecules behave

They cross the membrane and bind intracellular receptors

How do hydrophilic signaling molecules behave

They require cell surface receptors

What is meant by high specificity in ligand binding

Ligands bind only to specific receptors

What is meant by high affinity in ligand binding

Ligands bind tightly to receptors at low concentrations

What does a low Kd value indicate

High binding affinity between ligand and recepto