Module 9

Question 1

Signalling Cell

Answer 1

The source of a signalling molecule.

Question 2

Responding Cell/Target Cell

Answer 2

The cell that receives information from the signalling molecule.

Question 3

Receptor Activation

Answer 3

The turning on of a receptor which often occurs when a signalling molecule binds to a receptor on a responding cell.

Question 4

Response

Answer 4

A change in cellular behaviour such as activation of enzymes or genes following a signal.

Question 5

Paracrine Signalling

Answer 5

Signalling by a molecule that travels a short distance to the nearest neighbouring cell to bind its receptor and lead to a response. (20 cell distance)

Question 6

Endocrine Signalling

Answer 6

Signalling by molecules that travel through the bloodstream.

Question 7

Contact-Dependent Signalling/Juxtacrine Signalling

Answer 7

Signalling that involves direct contact between two cells, typically a ligand on one cell with a receptor on the other cell. The signalling molecule is not released from the cell, but instead remains associated with the cell membrane.

Question 8

Nonpolar Signalling Molecules

Answer 8

Molecules that enter the cell and bind to receptors found in the cytoplasm.

Question 9

G Protein

Answer 9

A protein that binds to the guanine nucleotides GTP and GDP. Active when bound to GTP. Inactive when bound to GDP.

Question 10

Phosphatase

Answer 10

An enzyme that removes phosphate groups from another molecule.

Question 11

Second Messenger

Answer 11

Signalling molecules found inside cells that relay information to the next target in the signal transduction pathway.

Question 12

Protein Kinase A (PKA)

Answer 12

An enzyme that becomes activated by cAMP.

Question 13

Signalling Molecule/Ligand

Answer 13

The carrier of information transmitted when the signalling molecule binds to a receptor.

Question 14

Signal Transduction

Answer 14

The process in which an extracellular molecule acts as a signal to activate a receptor which transmits information to the cell through the cytoplasm. The receptor transmits a message to the cell through the cytoplasm.

Question 15

Signal Termination

Answer 15

When the ligand dissociates from the receptor and the cell’s response goes in reverse.

Question 16

Autocrine Signalling

Answer 16

The signalling cell and the responding cell are one and the same.

Question 17

Ligand-Binding Site

Answer 17

The specific location on the receptor where a signalling molecule binds.

Question 18

Polar Signalling Molecules

Answer 18

Molecules that cannot enter the cell and bind to receptors outside of the cell.

Question 19

G Protein-Coupled Receptor

Answer 19

A receptor that couples to G proteins, which bind to the guanine nucleotides GTP and GDP.

Question 20

Receptor Kinase

Answer 20

A receptor that is an enzyme that adds a phosphate group to another molecule.

Question 21

Ion Channels

Answer 21

A channel-like membrane protein that regulates the flow of ions across the cell membrane.

Question 22

Cyclic AMP (cAMP)

Answer 22

A second messenger.

Question 23

Binding Affinity

Answer 23

The tightness of the binding between the receptor and the signalling molecule.

Question 24

Cellular Communication Elements

Answer 24

1) A Signalling Cell
2) A Signalling Molecule
3) A Receptor Protein
4) A Responding Cell

Question 25

Receptor Protein

Answer 25

The molecule on the responding cell that binds to the signalling molecule.

Question 26

Cell Signalling Process

Answer 26

1) Receptor Activation
2) Signal Transduction
3) Response
4) Termination

Question 27

Termination

Answer 27

The stopping of the response of a cell triggered by a signal.

Question 28

Growth Factor

Answer 28

A type of signalling molecule that causes the responding cell to grow, divide, or differentiate.

Question 29

Neurotransmitters

Answer 29

A type of signalling molecule released from a neuron.

Question 30

Adenylyl Cyclase

Answer 30

Converts the ATP into cyclic AMP (cAMP).

Question 31

First Messenger

Answer 31

Transmit signals from outside the cell to a receptor.

Question 32

Cell Signalling

Answer 32

Transferring information from the outside of the cell to obtain a response inside the cell.

Question 33

α Subunit

Answer 33

Part of the G protein that binds to either GDP or GTP.

Question 34

β Subunit

Answer 34

Part of the G protein.

Question 35

γ Subunit

Answer 35

Part of the G protein.

Question 36

Kinases

Answer 36

Enzymes that phosphorylate target proteins.

Question 37

Dimerization

Answer 37

The receptors associate into dimers (2 receptors into 1).

Question 38

Ligand-Gated

Answer 38

Respond to binding of a signalling molecule.

Question 39

Voltage-Gated

Answer 39

Respond to changes of voltage in the cell.

Question 40

Mechanically-Gated

Answer 40

Respond to force applied to the cell.

Question 41

Closed Gate

Answer 41

Prevents the movement of the ion.

Question 42

Open Gate

Answer 42

Allows the movement of the ion.

Question 43

Low Peptide Levels

Answer 43

Low density of bacteria. Gene expression is turned off.

Question 44

High Peptide Levels

Answer 44

High density of bacteria. Gene expression is turned on allowing DNA uptake from the environment.

Question 45

Hormones

Answer 45

Chemical signalling molecules.

Question 46

Types of Protein Receptors

Answer 46

1) G Protein-Coupled Receptors (GPCRs) (fast and quick)
2) Receptor Kinases (long-lasting)
3) Ion Channels

Question 47

Receptor Kinase Example

Answer 47

1) PDGF activates receptor.
2) Ras gets activated and activates kinase 1.
3) Kinase 1 activates kinase 2.
4) Kinase 2 activates kinase 3.
5) Kinase 3 activates transcription factors for gene expression.
6) The pathway is terminated when the GTP is replaced by GDP on Ras.