Cell to Cell Communication Unit

3 steps of cell to cell communication

1. signal reception

2. transduction

3. response

signal

molecule released by one cell and detected by another

local

in local extracellular matrix

where do signals pass

gap junction

pasmo desmata

gap junction in plant cells

direct contact

signal on one cell attach to receptor of another

paracrine signaling

release of local regulators that are picked up by target cell near by

synaptic signaling

local regulators released into synapse between neuron and other cell

long-distance

communication between cells in different parts of the body by endocrine system through hormones

reception

signal molecule binds to receptor protein causing it to change shape

ligand

signal molecule binds to receptor protein causing it to change shape

conformational change

shape change

intracellular receptors

inside cell cytroplasmic or nuclear membrane proteins that are acted on by small hydrophobic signal molecules that can pass through membrane

steroid hormones

long distance acting signals that can pass through nuclear pores and initiate or inhibit transcription

3 membrane receptor types

• G-protein linked

• tyrosine kinases

• ion channels

G-protein linked receptor

1. ligand attaches to membrane receptor and creates sites for inactive G-protein to bind

2. on G-protein gDP replaced by higher energy GTP

3. activated G-protein leaves and binds to other proteins activating them

kinases

enzymes that add phosphate

phosphotase

enzymes that remove phosphate

receptor tyrosine kinases

1. membrane receptors activated by signal and form dimer

2. in this configuration they pick up phosphate groups from ATP

3. tyrosine donate phosphate to intracellular proteins and activate them thus bringing about cellular response

ion channel receptors

1. required gated ion channels

2. passive transport

3. signal molecules attach to protein and open gated channel allowing ions to move down concentratopm gradient

transduction

cascades of molecular interactions relay signal from receptor to target molecules in cells amplifying signals and regulating by identifying for errors and switching off based on product requirement

phosphorylation cascade

requires kinase to activate and phosphotase to reset and is the continuous phosphorylation of enzymes

second messenger

intracellular signals that are small non-protein water soluble molecules or ions

AMP

ATP lost 2 phosphate

cyclic AMP

cAMP phosphate binds to sugar in two spots and acts as signal

________ trigger cAMP formation

G-proteins

______ ions act as second messenger when released into the ________

calcium/cytosol

_______ ions are sequested in ER mitochondria and extracellular fluid until needed by active transport and leased by ion-gated channel proteins

calcium

cleaving

split up

_______ used as ligand for gated channel proteins to release calcium ions

IP3

cytoplasmic

proteins can be activated or inhibited

nuclear response

genes can be activated or inhibited by turning transcription on or off

scaffolding protein

gathers proteins that need to be activated and activates them at once

signal response needs to be _________ quickly by ________ of the ligand so the next can be picked up and next __________ __________ is generated

terminated/release/cellular response