Chapter 6.3: Signal Transduction Allows a Cell to Respond Appropriately to a Signal

Flashcards from Chapter 6.3 of Principles of Life, 3rd Edition.

Signal transduction pathway

A cascade of events that occur after a signal is received to ultimately change cellular function

• Results in the amplification and distribution of a signal, which can result in different responses throughout an organism

Cellular response

What ultimately occurs at the end of a signal transduction pathway; includes:

• Ion channel openings, modifying concentrations (seen in nerves and muscles)

• Enzyme activity changes, altering metabolic rates

• Gene expression changes, which in turn alter protein abundance and later cell function

These may be different across different cell types

Signal transduction cascade

The set of steps where enzymes are activated or inhibited by other enzymes in a pathway

• Can involve a kinase phosphorylating a protein, resulting in activation or inhibition

• Seen with mitogen-activated protein kinases requiring several steps of phosphorylation and binding

Second messengers

Small non-protein molecules that can be hydrophilic, hydrophobic, or even gases

• Lack enzymatic activity and act through allosteric regulation

• Help distribute cell signals via several internal responses

• Examples include cAMP, IP₃, DAG, PIP₃, and NO

Epinephrine

A molecule that acts as a ligand for the activation of a G protein, enabling second messenger and amplifying enzyme interactions for the production of glucose from glycogen in the liver for emergencies