Hormone

"Your cells spend tremendous energy running these pumps. Receptor proteins detect signals from outside the cell - hormones, neurotransmitters, growth factors - and trigger responses inside. Recognition proteins act like ID badges, allowing immune cells to distinguish..."

"It's called apical dominance, and it's a brilliant resource allocation strategy. The tip of the main shoot (the apex) produces a hormone called auxin that suppresses the growth of lateral buds. Translation: the top of the tree chemically prevents side branches from growing too aggressi..."

"...d transmitting the signal throughout the cell. Signal Transduction: The Amplification Cascade Here's where cells reveal their genius. A single hormone molecule binds one receptor - just one molecule - but that receptor doesn't just whisper to the cell, it shouts."

"...roots/fruit (sink) where sugars are unloaded. - Contents: Sugars (10-30% concentration - sucrose primarily, also glucose, fructose), amino acids, hormones (auxin, cytokinin), signaling molecules, RNA - Structure: Living cells (sieve tube elements with perforated end walls, companion cells provide me..."

"...972, two research teams independently discovered that destroying the SCN in rats erased all circadian rhythms - sleep became random, eating sporadic, hormone release chaotic (Moore & Eichler; Stephan & Zucker). But the transplant studies were definitive: the SCN is both necessary and sufficient."