Cel Biology Notes Essay

357 WordsApr 12, 20152 Pages
• Cell signaling that alters existing protein function (e.g. changes in movement, secretion or metabolism) is fast (seconds – minutes) while that which alters gene expression (e.g. differentiation and cell growth & division) is slow (minutes – hours) • Types of signaling o Endocrine signaling → hormones (produced by endocrine cells) are signaling molecules that are sent through an organism’s bloodstream e.g. insulin (most ‘public’) o Paracrine signaling → signaling molecules diffuse locally through extracellular fluid, act as local mediators • Autocrine signaling → cells respond to signaling molecules that they themselves produce e.g. cancer cells o Neuronal signaling → private signaling through axons that release neurotransmitters (e.g. acetylcholine) onto their target cell o Contact-dependent signaling → two cells must make physical contact via plasma membrane-bound signaling molecules instead of secreting a signaling molecule (most ‘intimate’) • In drosophila nerve cell production, a developing nerve cell’s Delta signaling protein sends an inhibitory signal by making contact with surrounding epithelial cells’ Delta receptor (Notch) → inhibits surrounding cells from becoming neurons too (lateral inhibition) • A cell only responds to a signal for which it as a receptor → allows cell to be selective to signals • One signaling molecule can have many different effects depending on what type of cell receives the signal and how it interprets it • Signaling may direct a cell to survive, grow & divide, differentiate; in the absence of any signals, apoptosis is induced • Two types of extracellular signaling molecules that affect two classes of receptors o Molecules that are too large or hydrophilic to cross the membrane of the target cell → rely on cell-surface receptors o Small, hydrophobic molecules that can diffuse across target cell’s membrane →

More about Cel Biology Notes Essay

Open Document