Principles of Cell Signaling

Question 1

What are the signal types

Answer 1

Contact dependent
Paracrine
Synaptic
Endocrine

Question 2

What are the cell signal types organized by distance signal travels

Answer 2

Local (autocrine, contact-dependent, paracrine, synaptic)
Long distance (endocrine)

Question 3

What is the most common form of signaling

Answer 3

Paracrine

Question 4

How does paracrine signaling work

Answer 4

Cells respond to signaling molecules locally released by signaling cell

Question 5

How are responses kept local during paracrine signaling

Answer 5

Ligands are quickly degraded by enzymes or removed by neighboring cells

Question 6

How does autocrine signaling work

Answer 6

Signaling and target cell are the same, so cells respond to signaling molecules that they produce themselves

Question 7

What are some examples of cells that do autocrine signaling

Answer 7

Immune cells
Cancer cells

Question 8

How does synaptic signaling work

Answer 8

Neurotransmitters are the signals

Question 9

Paracrine signaling - speed and concentration of signals

Answer 9

Fast
Relatively concentrated

Question 10

How does endocrine signaling work

Answer 10

Endocrine cell secretes a hormone
Hormone travels in blood to target

Question 11

Endocrine signaling - speed and concentration of signals

Answer 11

Slow - relies on blood flow and diffusion
Dilute - low concentrations of hormones

Question 12

How does contact-dependent signaling work

Answer 12

Cell-cell signaling that requires close contact
Can be membrane-bound signaling molecules or be shared through gap junctions

Question 13

What are some types of ligands

Answer 13

Proteins, peptides, amino acids, small molecules. lipids, ions

Question 14

What are ligands

Answer 14

Chemical signals for cell communication

Question 15

What are the classes of signaling receptors

Answer 15

G-protein coupled receptors
Enzyme-linked receptors
Ligand-gated ion channels
Nuclear receptors

Question 16

General rundown of GPCRs

Answer 16

Transmembrane receptor at cell surface
Binds extracellular ligands
Binding activates G protein

Question 17

Types of enzyme-linked receptors

Answer 17

1 - intrinsic enzymatic activity (enzyme-coupled)
2 - enzyme-associated receptor

Question 18

General rundown of enzyme-coupled receptors

Answer 18

Extracellular ligand binds and induces dimerization
Activates catalytic activity on cytoplasmic side

Question 19

General rundown of enzyme-associated receptors

Answer 19

Extracellular ligand binds
Enzyme recruited and activated on the cytoplasmic side

Question 20

General rundown of intracellular receptors

Answer 20

Intracellular - cytoplasm or nucleus
Receptors bind to DNA and alter transcription

Question 21

General rundown of ligand-gated ion channels

Answer 21

Cell-surface transmembrane receptors
Ions are signaling molecules

Question 22

What are the steps of the signaling cascade

Answer 22

Reception
Transduction
Response

Question 23

What happens during reception

Answer 23

Ligand binds to receptor protein
Receptor protein changes shape
Change in shape begins a series of events

Question 24

What happens during transduction

Answer 24

A series of events “transduces” signal
Signal is often amplified

Question 25

What organized the signaling proteins during transduction?

Answer 25

Scaffold proteins

Question 26

What is the result of transduction (eg. the next step)

Answer 26

response - activation of effector proteins (trans. regulation, enzyme, etc)
Behavior of the cell is altered

Question 27

What is convergent signaling?

Answer 27

Signals from unrelated receptors converge to activate the same effector

Question 28

What is divergent signaling

Answer 28

One signal diverges to act on different receptors

Question 29

What is cross-talk

Answer 29

When signals move between pathways

Question 30

Can all cells receive a certain signal?

Answer 30

No, cells must have the receptor appropriate to the signal

Question 31

Do all ligands produce the same results?

Answer 31

No. Ex. - acetylcholine has different results for skeletal vs heart muscle