Chapter 11: Cell Communication

Question 1

What are the 3 types of local signaling?

Answer 1

1) Intracellular
2) Cell surface
3) Paracrine and synaptic

Question 2

What is intracellular signaling?

Answer 2

• Signaling through two cells that are touching each other

- Signaling molecules are small and cross through gap junctions/plasmodesmata

Question 3

How do intercellular receptors work?

Answer 3

• Located inside the cell (intracellular matrix)
• Float in the cytoplasm
• Hormone must be small and hydrophobic to go through the membrane

Question 5

What is cell surface signaling?

Answer 5

• Signaling through the ligand of one cell attached to the receptor of another cell (but the cells are not physically touching)

Question 6

What is paracrine and synaptic signaling?

Answer 6

• Signaling through nearby cells (not touching whatsoever)
• Signaling molecules are secreted into the cytoplasm and diffuse nearby cells
• Synaptic signaling occurs in the synapse

Question 7

What is the one type of long distance signaling?

Answer 7

Endocrine signaling

Question 8

What is endocrine signaling?

Answer 8

• When endocrine cells secrete hormones that travel long distances in the blood stream
• It will go to different receptors on different target cells

Question 10

What is reception?

Answer 10

• Signaling molecule (ligand) binds to receptor

- Receptor changes in response to binding (shape & location)

Question 11

What is transduction?

Answer 11

Relaying a message. Letting the body know I’ve received the signal.

Question 12

What is response?

Answer 12

When the cell does something based on the signal

Question 14

Explain how the G Protein-Coupled Receptor (GPCR) functions.

Answer 14

1) Signal molecule binds to site
2) G protein, carrying GDP, connects to G Protein Coupled Receptor: activated. (GDP is given off).
3) G protein, carrying GTP, connects to the inactive enzyme (activating it).
4) Cellular response (GTP is given off and the cycle restarts)

Question 15

What will happen to GPCR signaling if [GTP] is low?

Answer 15

The signal will not be transduced to the enzyme

Question 16

What are receptor tyrosine kinases (RTK)?

Answer 16

Proteins

Question 17

Explain how RTK functions.

Answer 17

1) Two RTK proteins accept signaling molecules.
2) The two proteins are activated and they join to form a dimer.
3) ATP, from inside the cell, attaches phosphates to the tyrosines.
4) Cellular response

Question 18

Is RTK endergonic or exergonic?

Answer 18

Endergonic

It requires ATP

Question 19

What are ion channel receptors?

Answer 19

Proteins with gated channels

Question 20

Explain how the ion channel receptors function.

Answer 20

1) Gate closed.
2) Signal molecule binds to active site.
3) Gate opens.
4) Ions flow down their concentration gradients from the extracellular matrix into the intercellular matrix.
5) Cellular response

Question 21

An increase in cholesterol that decreases membrane fluidity will slow signaling for which receptors proteins?

Answer 21

• G Protein-Coupled Receptors
• Receptor Tyrosine Kinases (RTK)
• Ion Channel Receptors

Question 23

What’s an example of reception?

Answer 23

G Protein-Coupled Receptors

• vision, smell, taste
• if something binds with it, it’s folding changes

Question 27

What are the 3 stages of cell signaling?

Answer 27

1) Reception
2) Transduction
3) Response