Chapter 9 - Cell Communication

Question 1

cell signaling

Answer 1

Part of a complex system of communication that governs basic cellular activities and coordinates cell actions. The ability of cells to perceive and correctly respond to their microenvironment is the basis of development, tissue repair, and immunity as well as normal tissue homeostasis.

Question 2

ligand

Answer 2

A small molecule that forms a complex with a biomolecule to serve a biological purpose. In protein-ligand binding, the ligand is usually a signal-triggering molecule, binding to a site on a target protein. A protein that binds to the DNA double helix.

Question 3

receptor protein

Answer 3

An intracellular protein or protein fraction having a high specific affinity for binding agents known to stimulate cellular activity, such as a steroid hormone or cyclic AMP.

Question 4

receptor

Answer 4

A protein molecule usually found embedded within the plasma membrane surface of a cell that receives chemical signals from outside the cell.

Question 5

signal transduction

Answer 5

The transmission of molecular signals from a cell’s exterior to its interior.

Question 6

cellular response

Answer 6

The binding of chemical signals to their corresponding receptors induces events within the cell that ultimately change its behaviour. The nature of these intracellular events differs according to the type of receptor. Also, the same chemical signal can trigger different responses in different types of cell.

Question 7

membrane receptor

Answer 7

Cell surface, membrane-anchored, or integral proteins that bind to external ligand molecules. This type of receptor spans the plasma membrane and performs signal transduction, converting an extracellular signal into an intracellular signal.

Question 8

intracellular receptor

Answer 8

Receptors located inside the cell rather than on its cell membrane. Classic hormones that use intracellular receptors include thyroid and steroid hormones.

Question 9

direct contact

Answer 9

A type of cell / cell or cell / extracellular matrix signalling in multicellular organisms that requires close contact.

Question 10

paracrine signaling

Answer 10

A form of cell-cell communication in which a cell produces a signal to induce changes in nearby cells, altering the behavior or differentiation of those cells.

Question 11

endocrine signaling

Answer 11

Occurs between distant cells and is mediated by hormones released from specific endocrine cells that travel to target cells, producing a slower, long-lasting response.

Question 12

synaptic signaling

Answer 12

Similar to paracrine signaling but there is a special structure called the synapse between the cell originating and the cell receiving the signal. Synaptic signaling only occurs between cells with the synapse; for example between a neuron and the muscle that is controlled by neural activity.

Question 13

hormone

Answer 13

Any member of a class of signaling molecules produced by glands in multicellular organisms that are transported by the circulatory system to target distant organs to regulate physiology and behaviour.

Question 14

phosphorylation

Answer 14

The addition of a phosphate (PO43−) group to a protein or other organic molecule. Phosphorylation turns many protein enzymes on and off, thereby altering their function and activity. Protein phosphorylation is one type of post-translational modification.

Question 15

dephosphorylation

Answer 15

The removal of a phosphate (PO43−) group from an organic compound by hydrolysis. It is a reversible post-translational modification that is coupled to the addition of phosphate groups, or phosphorylation.

Question 16

protein kinase

Answer 16

A kinase enzyme that modifies other proteins by chemically adding phosphate groups to them (phosphorylation).

Question 17

phosphateses

Answer 17

An enzyme that removes a phosphate group from its substrate by hydrolysing phosphoric acid monoesters into a phosphate ion and a molecule with a free hydroxyl group. Directly opposite to that of phosphorylases and kinases

Question 18

channel-linked receptor

Answer 18

Cell membrane bound receptors that act through synaptic signaling on electrically excitable cells and convert chemical signals (ligand) to electrical ones.

Question 19

enzymatic receptor

Answer 19

A transmembrane receptor, where the binding of an extracellular ligand causes enzymatic activity on the intracellular side.

Question 20

G protein-linked receptor

Answer 20

Protein located in the cell membrane that binds extracellular substances and transmits signals from these substances to an intracellular molecule called a G protein (guanine nucleotide-binding protein).

Question 21

RTK

Answer 21

The high-affinity cell surface receptors for many polypeptide growth factors, cytokines, and hormones in animals. Similar to plant receptor kinases.

Question 22

signal amplification

Answer 22

Example of signal amplification. The use of specific detection methodologies to directly increase the signal in proportion to the amount of target in the reaction. Examples include the use of branched DNA probes that contain a reporter group or enzyme amplification.

Question 23

kinase cascade

Answer 23

Series of protein kinases that phosphorylate each other in succession; a kinase cascade can amplify signals during the signal transduction process.

Question 24

GPCR

Answer 24

G protein coupled receptor. A receptor that acts through a 3 component G protein to activate effector proteins them function as enzymes to produce second messengers such as cAMP or IP3.

Question 25

cAMP

Answer 25

Helps catabolite activator protein bind to DNA and activate transcription. Level of cAMP is inversely related to the level of glucose.

Question 26

adenylyl cyclase

Answer 26

An enzyme that produces large amounts of cAMP from ATP; the cAMP acts as a second messenger in a target cell.

Question 27

calmodulin

Answer 27

A protein containing 148 amino acid residues that mediates Ca2+ function. When4 4 Ca2+ are bound, Calmodulin can bind to other cytoplasmic proteins and effect cellular responses.

Question 28

G protein

Answer 28

Assisting protein that binds the nucleotide guanosine triphosphate (GTP).

Question 29

plant receptor kinase

Answer 29

Recognize hydrophilic ligands and form a large class of membrane receptors much like RTKs