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Emily Lakic AP Biology Cell Communication Quiz/Chpt. 9

Cell Communication Background RECEPTION → TRANSDUCTION → RESPONSE -

Reception -

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Signal molecule binds to receptor protein

Transduction -

Interaction of the receptor protein and signaling molecule changes the shape of the receptor protein and initiates a series of reactions called a transduction pathway

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Response -

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What molecules are used as signals? -

Peptides

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Large proteins

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Individual amino acids

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Nucleotides

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Steroids

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Other lipids

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NO (nitric oxide)

A multicellular organism’s cell is constantly surrounded by hundreds of signals -

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Transduction reactions convert the information in the signal into a cellular response

However, the cell will only respond to certain signals

How does a cell choose which signal to respond to? -

The number and kind of receptor molecules

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When a ligand approaches a receptor protein, if they have complementary shapes, they will bind -

This forms a complex

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This induces a change in the receptor protein’s shape and therefore initiates a response in the cell via a signal transduction pathway

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A given cell responds to the signaling molecules that fit the particular set of receptor proteins it possesses and ignores the signaling molecules that do not

Emily Lakic AP Biology Cell Communication Quiz/Chpt. 9

Signaling is defined by the distance from source to receptor -

Cells can communicate depending primarily on the distance between the signaling molecules and the responding cells

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4 basic types of cell signaling (1) DIrect Contact -

Two cells in direct contact with each other in 2 ways

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1st way

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One cell may have many lipids, proteins, nucleic acids, etc. on its P.M.

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Second cell may have receptor proteins that recognize these molecules on its P.M.

2nd way -

Send signals across gap junctions

(2) Paracrine Signaling -

Short-lived signals

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Has local effects

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Travel through the fluid between cells

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Signals that diffuse out of cells and cross into the extracellular matrix

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If they do not have a cell to travel to because molecules are taken up by neighboring cells, destroyed by extracellular enzymes, or quickly removed from the extracellular fluid in some other way, their influence is restricted to cells in the vicinity of the cell it left

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Also plays important role in developmental changes

(3) Endocrine Signaling -

Long-lived signals

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Released from cell and remain in extracellular fluid

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Has ability to travel through circulatory system and whole body

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May affect cells very distant from releasing cell

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Ex. Hormones

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Used by both animals and plants

(4) Synaptic Signaling -

Neurotransmitters are released from the tips of nerve cells very close to the target cells

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Chemical synapse -

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Association of a neuron and its target cell

Neurotransmitters cross the synaptic gap and persist only briefly

Emily Lakic AP Biology Cell Communication Quiz/Chpt. 9

(5) Autocrine Signaling -

Some cells send signals to themselves

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Secrete signals that bind to specific receptors on their own plasma membranes

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Plays important role in -

Developmental changes

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Immune system

Signal transduction pathways lead to cellular responses -

Signal transduction -

Events that occur within the cell when receiving a signal

Phosphorylation is key in control of protein function

Protein kinases

Phosphatases

Receptor Types

Receptors are defined by location

Membrane receptors include three subclasses

Channel-linked receptors...