AP Bio Unit 4 - topics 1-4

Growth/development of multicellular organisms

Direct contact, local signaling, and long distance signaling

communication through cell junctions

Pass freely between adjacent cells.

gap junctions

plasmodesmata

immune cells

Secreting cell that will release chemical messages through extra cellular fluid

Paracrine and synaptic

Separatory cell releases messages (via Exocytosis) to adjacent cell

in the animal nervous system; specialized type of local signaling

Neuron secretes neurotransmitters that diffuse across synaptic cleft

plants and animals use chemicals called hormones

Release hormones I plant vascular tissue (xylem or pholem) or through air to reach target

Endocrine signaling:

Specialized cells release hormones into the blood stream ( circulatory system )

Released by pancreas into bloodstream where it circulates in the body

Reception, transduction, response

The target cell's detection of a signal molecule coming from outside the cell.

protein that detects a signal molecule and performs an action in response

The receptor undergoes a conformational change and activates

Plasma membrane or intracellular fluid

Large, polar, hydrophilic(most common in signaling pathways)

small or nonpolar ligands can diffuse across the cell membrane

Steroid/Hormone nuclear receptors

Example in intracellular receptors

G protein, ligand gated ion channels

The conversion Of an extra cellular signal to intracellular, signaling that will bring about a cellular response

a sequence of changes in a series of molecules known as a signal transduction pathway

Phosphorylation by enzyme kinase

Depphosphorylation by phosphatase (shuts off pathways)

Relay signal inside cell

Transduction

Small, non-protein water soluble molecules or ions that send messages throughout the cells by diffusion and amplify the response

cyclic AMP (cAMP)

The final molecule in the signaling pathway will convert the signal to a response they will alter a cellular response.

How a cell responses to its environment

Change in gene expression and cell function which can alter phenotypes

Mutations to receptor proteins or to any component of the signaling pathways

G protein coupled receptors (GPCRs) and Ion channels

Largest categories of cell surface receptors

Important for animal sensory systems

Binds to G protein that binds to GTP

energy molecules similar to ATP

Cytoplasmic side to change shape, allowing G protein to bind to GPCR and G protein GDP becomes GTP

It activates the enzyme and amplifies the signal and leads to a cellular response

Nervous system

Receptors that act as a gate for ions

When ligand binds to receptor, gate opens or closes allowing for the diffusion of specific ions (leads to cellular response )

highly specific