Chapter 11: Cell Communication

Question 1

Hormone

Answer 1

-In multicellular organisms, one of many types of secreted chemicals that are formed in specialized cells, travel in body fluids, and act on specific target cells in other parts of the body, changing the target cells’ functioning

Question 2

Signal Transduction Pathway

Answer 2

Series of steps linking a mechanical, chemical, or electrical stimulus to a specific cellular response

Question 3

Ligand

Answer 3

Molecule that binds specifically to another molecule, usually a larger one

Question 4

G-Protein Coupled Receptor (GPCR)

Answer 4

• SIgnal receptor protein in the plasma membrane

- Responds to the binding of a signalling molecule by activating a G protein

Question 5

G Protein

Answer 5

• A GTP-binding protein

- Relays signals from a plasma membrane signal receptor (GPCR) to other signal transduction proteins inside the cell

Question 6

Receptor Tyrosine Kinase

Answer 6

• Receptor protein spanning the plasma membrane, the cytoplasmic (intracellular) part of which can catalyze the transfer of a phosphate group from ATP to a tyrosine on another protein
• Often respond to binding of a signal molecule by dimerizing and then phosphorylating a tyrosine on the cytoplasmic portion of the other receptor in the dimer

Question 7

Ligand-Gated Ion Channel

Answer 7

• Transmembrane protein
• Contains a pore that opens/closes as it changes shape in response to a signaling molecule, allowing/blocking the flow of specific ions
• Also called an ionotropic receptor

Question 8

Protein Kinase

Answer 8

An enzyme that transfers phosphate groups from ATP to a protein, thus phosphorylating the protein

Question 9

Phosphorylation Cascade

Answer 9

• Series of protein phosphorylations occurring sequentially
• Each protein kinase phosphorylates the next, activating it
• Often found in signaling pathways

Question 10

Protein Phosphatase

Answer 10

• Enzyme that removes phosphate groups from (dephosphorylates) proteins
• Often functioning to reverse the effect of a protein kinase

Question 11

Second Messenger

Answer 11

• Small, nonprotein, water-soluble molecule or ion (i.e. calcium ion or cyclic AMP)
• Relays a signal to a cell’s interior in response to a signal received by a signal receptor protein

Question 12

Cyclic AMP (cAMP)

Answer 12

• Cyclic adenosine monophosphate
• RIng-shaped molecule made from ATP
• Common intracellular signaling molecule in eukaryotic cells
• Regulator of some bacterial operons

Question 13

Adenylyl Cyclase

Answer 13

Enzyme that converts ATP to cyclic AMP in response to an extracellular signal

Question 14

Inositol Triphosphate (IP3)

Answer 14

• Second messenger
• Functions as an intermediate between certain signaling molecules and a subsequent second messenger (CA2+) by causing a rise in cytoplasmic CA2+ concentration

Question 15

Diacylglycerol (DAG)

Answer 15

Second messenger produced by the cleavage of the phospholipid PIP2 in the plasma membrane

Question 16

Scaffolding Protein

Answer 16

Type of large relay protein to which several other relay protein are simultaneously attached, increasing the efficiency of signal transduction

Question 17

Apoptosis

Answer 17

• Type of programmed cell death

- Brought about by activation of enzymes that break down many chemical components in the cell