Cell Communication

Cell communication involves

Responding to signals and producing outgoing signals

Why is Cell communication important

to respond to a changing environment and to communicate with other cells

What happens in Direct Intercellular Signaling

Cell junctions allow signals to directly pass one another

What happens in Contact-Dependent Signaling

A molecule bound to the surface of cells serve as signals to cells coming in contact with them

What happens in Autocrine Signaling

cells secrete signaling molecules that bind to their own surface receptors

What happens in Paracrine Signaling

cells release signals that affect nearby cells

What happens in Endocrine Signaling

signals are released into blood and affect targets far away

The three common stages of Cell Signaling

1. Receptor activation

2. Signal transduction

3. Cellular Response

True or False: Ligand binding changes the receptor structure

True, this change sends a signal across the membrane

What does K_on mean

the rate at which binding occurs

What does K_off mean

the rate of dissociation of the ligand receptor complex

What does K_d mean

the dissociation constant, used to check the affinity of the receptors with their ligand K_d=K_off/K_on

True or False K_d is inversely related to the affinity between its ligand and its receptor

True, K_d also reflects the ligand concentration when half are active

If Ligand concentration is above K_d then

most receptors are likely to have a ligand bound to them

If Ligand concentration is below K_d then

most receptors will not be bound to their ligand

Why can’t signaling molecules pass through the membrane

they are small and hydrophilic, or too large

Cell surface receptors are embedded in the membrane and detect what type of signals

extracellular signals

3 Types of Receptors

1. Enzyme-Linked Receptors

2. G-Protein-coupled Receptors

3. Ligand-Gated Ion channels

What do Enzyme-Linked Receptors contain

A extracellular signal binding domain and a intracellular catalytic domain. (they transfer phosphate group from ATP to a specific amino acid in target proteins

What does G-protein-coupled Receptors contain

G-proteins that bind GTP to GDP and causes their a and b/y dimer subunits to disassociate

What does Ligand-Gated ion channels contain

ion channels that let the flow of ions across the membrane

Where are intracellular receptors found

in the cytosol or nucleus

what happens when u active a intracellular receptor

gene expression changes

Who uses intracellular receptors

Steroid hormones like, estrogen and testosterone

What happens when an enzyme-linked receptor is activated

The phosphorylation of a intracellular protein

What receptors do intracellular receptors bind to

signal molecules that are small and hydrophobic