AP Biology 4.1-4.5

Direct Contact

Cell Communication when 2 cells are touching

Cell Recognition

Cell communication when receptors bind

Paracine/Local Signaling

Don’t touch, but send signals over short distances

Synaptic Signaling

Neurons sending signals

Long-Distance Signaling

Basically endocrine system. Cell releases hormones into the bloodstream, carries it everywhere in the body.

Long Distance Signaling

Bloodstream always =

Endocrine

Hormones always =

Signal Transduction

Receptor binds to membrane protein → signals some cellular response → another till you get to your goal.

Phosphorylation Cascade

One reaction leads to mass phosphorylation

Hydrophilic

Cell receptors are on the outside

Hydrophobic

Cell receptors are on the inside.

GPCRs (G-Protein-Coupled Receptors)

Receptor coupled w/ G-protein, molecule attaches to receptors → g protein is activated → g protein is phosphorylation → cascade of phosphorylation.

RTK (Receptor Tyrosine Kinases)

Two receptors that when attached to signal molecules, come together to phosphorylate tyrosines.

Amino acids on a protein

Tyrosines

Ligand-gated Ion Channels

When signal binds, lets ions in through the channel; ions can function as activators of a protein (secondary messagners)

Secondary Messangers

Don’t directly activate proteins, but created after a receptor is activated (CaMP, Ca2+). Small, water soluble molecules that can diffuse quickly. May or may not need activation before they are able to move the signal on to the next step in the process.

Kinase

Something that adds a phosphate group; activate phosphorylation

Phosphatases

Take out phosphate and deactivate pathway → used for cholera (tells cells to secrete water)

Tases = tasers

Memorization trick for Phosphateses

Demosones

Cell junctions where rivets connect cells.

Gap Junctions

Cell junctions connected by a gap

Tight Junctions

Cell junctions connected so tightly together that water can’t pass through. Seen in skin.

Homestasis

Cell maintaining balance

Negative Feedback

Cell response that decrease reaction. Ex: Regulating temp.

Positive Feedback

Cell response that amplifies the feedback. Ex: Childbirth

Apostosis

Cell response that’s programmed cell death, if not killed → tumor → cancer

Relay Molecules

Proteins that require activation. Large and don’t diffuse through the cell quickly.

Symbiosis

Interaction between two different organisms living in close physical association, typically to the advantage of both.

cAMP (cyclic AMP)

Universal second messenger that plays a crucial role in the intracellular signal transduction of various stimuli controlling a wide variety of cellular events including secretion, cell proliferation, differentiation, migration, and apoptosis.

Quorum Sensing

Bacteria’s ability to produce and release chemical signal molecules in response to fluctuations in cell-population density.