Cell Signaling 2.4 U2

Question 1

What do cells need to be able to do?

Answer 1

Get information from their surroundings and other cells
Send information out for other cells to receive
In multicellular organisms, be able to coordinate complex functions that involve many different cells
Communicate within themselves! (ex. organelle to organelle)

Question 2

What is a ligand?

Answer 2

Signaling molecule that binds to a certain receptor

Question 3

What is a receptor?

Answer 3

A protein that “receives” the ligand and causes some effect

Question 4

What is a target cell?

Answer 4

A cell that has the receptor for a particular ligand

Question 5

What is a non-target cell?

Answer 5

A cell that does NOT have the receptor for a particular ligand

Question 6

What are the three stages of cell communication?

Answer 6

Reception, Transduction, and Response

Question 7

What are the types of receptors?

Answer 7

Internal receptors
Cell-surface receptors

Question 8

What are internal receptors?

Answer 8

In cytoplasm
Ligand has to enter cell to bind

Question 9

What are cell-surface receptors?

Answer 9

In cell membrane
Three main types:
Ion-channel linked receptors
G-protein coupled receptors
Enzyme-linked receptors

Question 10

What is a ion-channel linked?

Answer 10

When the ligand binds, the transmembrane channel opens, allowing ions to move through it.

Question 11

What is a G-protein coupled?

Answer 11

When the ligand binds, the receptor interacts with a G-protein which starts the signal transduction chain of events.
The receptor has seven transmembrane regions.
GTP to GDP

Question 12

What is an enzyme-linked?

Answer 12

When the ligand binds, the receptor activates an enzyme, which starts the signal transduction chain of events.

Question 13

What is a signal transduction?

Answer 13

Intracellular
Series of signaling events, like a chain reaction

Question 14

What are the responses to cell signaling?

Answer 14

Depends on the particular signal! But, often:
Changes in gene regulation
Turning expression of certain genes on/off
Regulates another protein’s activity

Question 15

What are examples of responses to cell signaling?

Answer 15

A growth factor binding to a cell causes an increase in the expression of genes that allow the cell to grow and divide!
When adrenaline binds to a muscle cell, it inactive the enzyme responsible for storing glucose and activates the enzyme responsible for producing glucose!

Question 16

What is bacterial communication?

Answer 16

At a certain density, the cells “decide” to change what they are doing. This works by the bacteria cell producing a ligand. When there is a low density of cells, there are less receptors for the ligand to bind to which results in no cellular response. When there is a higher concentration, there are more ligands and receptors. Once the ligands bind, they activate specific genes in the chromosomes of bacterial cells.

Question 17

What is bacterial communication examples?

Answer 17

Biofilm. The biofilm creates optimal conditions for the further growth of the organisms living within it.

Question 18

What is direct contact?

Answer 18

Signaling between cells that are touching one another. This allows substances to move from one cytoplasm to the next

Question 19

What is paracrine?

Answer 19

Paracrine signals move by diffusion through the extracellular matrix. This causes a quick response that lasts a short amount of time. The ligands are quickly degraded by enzymes to keep the concentration gradient.

Question 20

What is autocrine?

Answer 20

The cell releases a ligand that binds to a receptor on the cell that released it.

Question 21

What is endocrine?

Answer 21

The Cell releases ligands that travel through the circulatory system slowly. They connect to the receptor of the target cell and are active for a very long time(since there is a low concentration of them). These ligands are called hormones.

Question 22

What is direct contact examples?

Answer 22

Gap junctions, like cardiac muscles within the heart. It’s important for the muscles to communicate quickly so that their contractions happen simultaneously, allowing the heart to beat properly.

Question 23

What is paracrine examples?

Answer 23

An example of this is between nerve cells. To allow signal transmission between cells to be fast, they use Paracrine. This enables an immediate response.

Question 24

What is autocrine examples?

Answer 24

An example is in the early development of an organism to ensure that cells develop into the correct tissues and take on the proper function.

Question 25

What is endocrine examples?

Answer 25

An example of this is the pancreas, one of the endocrine glands that regulates the body’s blood glucose levels. Produces Insulin that travels through the bloodstream and connects to a liver cell receptor. This produces glycogen that can store glucose for later.