Communication in living systems is normally not covered in the 10th grade biology curriculum. Because of this, you
should take the time to examine this topic. Chapter 11: Cell Communication is our first step in understanding this idea.
In this outline you will find the AP Bio curriculum that is addressed in chapter 11.
Big Idea #3 – Living Systems, store, retrieve, transmit and respond to information essential to life processes.
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Enduring Understanding 3.B Expression of genetic information involves cellular and molecular mechanisms.
o Essential Knowledge 3.B.2 A variety of intercellular and intracellular signal transmissions mediate gene
expression (11.1 and 11.4) (45.1 and 45.2)
 Signal transmission within and between cells mediates gene expression (11.4)
 cAMP (11.3)
 Signal transmission within and between cells mediates cell function (11.1)
Enduring Understanding 3.D Cells Communicate by generating, transmitting and receiving chemical signals
o Essential Knowledge 3.D.1 Cell communication processes share common features that reflect a shared
evolutionary history (11.1 and 45.2)
 Communication involves transduction of stimulatory or inhibitory signals from other cells,
organisms or the environment (11.1)
 Correct and appropriate signal transduction processes are generally under strong selective
pressure
 In single-celled organisms, signal transduction pathways influence how the cell responds to its
environment (Handout and 11.1)
 Quorum sensing (TED talk)
 Reproduction & Developmental pathways
 Response to external signals by bacteria that influences cell movement
 In multicellular organisms, signal transduction pathways coordinate the activities within
individual cells that support the function of the organism as a whole
 Epinephrine stimulating glycogen breakdown (11.4)
 Temperature determination of sex in vertebrate organisms (handout)
o Essential Knowledge 3.D.2 Cells communicate with each other through direct contact with other cells or
from a distance via chemical signaling (11.1, 11.2, 45.1, 45.2)
 Cells communicate by cell-to-cell contact
 Cells communicate over short distances by using local regulators that target cells in the vicinity
of the emitting cell
 Quorum sensing
 Signals released by one cell type can travel long distances to target cells of another cell type
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o Essential Knowledge 3.D.3 Signal transduction pathways link signal reception with cellular response
(11.2, 11.3)
 Signaling begins with the recognition of a chemical messenger (ligand) by a receptor protein
 Specific one-to-one relations between receptor and messenger
 Receptor changes shape to respond to signal triggering signal transduction
o G-protein linked receptors
o Ligand-gated ion channels
o Receptor tyrosine kinases
 Signal transduction is the process by which a signal is converted to a cellular response
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Second messengers are often essential to the function of the cascade
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 Ligand-gated ion channels
 Second messengers: cyclic GMP, cyclic AMP, calcium ions, inositol triphosphate
 Many signal transduction pathways include protein modification (i.e. methylation of DNA) and
phosphorylation cascades (via a series of protein kinases)
Essential Knowledge 3.D.4 Changes in signal transduction pathways can alter cellular responses (11.1,
11.2, 11.3, 11.4)
 Blocked or defective pathways = deleterious, preventative or prophylactic