Module 4: Cell Signaling and Cell to Cell Communication

Question 1

Bacteria (prokaryotes) can talk to each other through the diffusion of certain chemicals; one example of this is

Answer 1

Quorum sensing

Question 2

Disease-causing bacteria will not produce toxins until they sense an adequate population of themselves. This increases _____

Answer 2

This increase the probability to survive host defenses, such as antibodies

Question 3

Microbes in a biofilm can ______ with each other

Answer 3

Communicate

Question 4

Interceller

Answer 4

Between cells, often based on ligands and receptor

Question 5

Intracellular

Answer 5

Within cells, based on nuclear and cytoplasmic signal transduction

Question 6

Small hydrophobic ligands

Answer 6

Usually transported by carrier proteins

Question 7

Hydrophilic ligands

Answer 7

Usually large, will not cross the plasma membrane; generally bind to extracellular receptors

Question 8

Internal receptors

Answer 8

Generally respond to hydrophobic ligands that can cross the plasma membrane
Many internal receptors bind directly to DNA after binding to the ligand. Can directly influence gene expression in this way

Question 9

Cell-surface receptors

Answer 9

Integral proteins that bind to external ligands
Interact with other proteins on the membrane and participate in signal transduction
Extracellular signal is converted to an intracellular signal

Question 10

How many types of cell-surface receptors?

Answer 10

3

Question 11

Ion channel-linked receptors

Answer 11

Binding of a ligand causes a conformational change, allowing the passage of the ion/molecule

Question 12

G-protein-linked receptors

Answer 12

When signal molecule is entered, GTP is hydrolyzed to GDP, leading to a dissociation of the G protein subunits that mediate downstream cell signals

(activate when bound to GTP, inactive when bound to GDP)

Question 13

G-protein-coupled receptors result in

Answer 13

Short term response

Question 14

Enzyme-linked receptors

Answer 14

When signaling molecules bind to the receptors, they dimerize. Tyrosine residues phosphorylate and a cellular response is released inside the cell

Question 15

Kinase receptors usually operate in

Answer 15

Pairs

Question 16

Kinase receptors result in

Answer 16

Long term responses

Question 17

Intracrine signaling

Answer 17

The signal is any hormone or ligand acting inside the cell, receptor is also inside the cell

Question 18

Autocrine signaling

Answer 18

Signal is produced inside cell then sent outside cell, where it binds with a receptor on that same cell

Question 19

Gap junctions

Answer 19

Allows signaling between adjacent cells. Only small molecules can pass through (like ions), large molecules like DNA and proteins can’t

Question 20

Juxtracrine signaling

Answer 20

Targets adjacent cells by direct contact

Question 21

Endocrine signaling

Answer 21

Signals from distant cells. Slower response but have longer-lasting effect

Question 22

Pheromones

Answer 22

Chemicals capable of acting like hormones outside the body of the secreting individual

Question 23

Cellular communication essentials

Answer 23

Signaling cell, signaling molecule, receptor protein, responding cell

Question 24

Signaling involves

Answer 24

Receptor activation, signal transduction, response, and response termination

Question 25

Phosphorylation is done by

Answer 25

Kinases

Question 26

Phosphorylation is

Answer 26

The addition of a phosphate group to a molecule such as a protein

Question 27

The overall effect of G-protein coupled receptor activation

Answer 27

Signal amplification

Question 28

cAMP and Ca+ are

Answer 28

Second messengers

Question 29

Second messengers serve as

Answer 29

signal amplification

Question 30

Effect of phosphorylation on proteins:

Answer 30

causes conformation changes to the proteins