Bio 11

Question 1

What is Cell-to-Cell Communication essential for?

Answer 1

Development, survival, and reproduction of multicellular organisms.

Question 2

What role do external signals play in cellular processes?

Answer 2

They affect the metabolism of target cells and help to regulate cellular processes.

Question 3

What is signal transduction?

Answer 3

The process by which a chemical signal is converted to a specific cellular response.

Question 4

What is endocrine signaling?

Answer 4

Signal molecules (hormones) secreted by an endocrine gland into the bloodstream acting on another target cell.

Question 5

What is paracrine signaling?

Answer 5

Signal molecules produced in one cell that act on neighboring cells.

Question 6

What is autocrine signaling?

Answer 6

Signal molecules produced in one cell that act on the same cell.

Question 7

What is synaptic signaling?

Answer 7

Signal molecules (neurotransmitters) released from a neuron affecting other cells.

Question 8

What is neuroendocrine signaling?

Answer 8

Signal molecules (hormones) released from nerve cell endings into the bloodstream due to neurological stimulation.

Question 9

What are the three stages of cell signaling?

Answer 9

• Reception
• Transduction
• Response

Question 10

What is required for a target cell to respond to a regulatory chemical?

Answer 10

Specific receptor proteins for that signaling molecule.

Question 11

What is the function of intracellular receptors?

Answer 11

They are receptor proteins within the cytoplasm that bind to hydrophobic signal molecules.

Question 12

What is the role of cell membrane receptors?

Answer 12

They are receptor proteins on the outer surface of the target cell membrane that bind to hydrophilic signal molecules.

Question 13

What are second messengers?

Answer 13

Intracellular mediators of hormones whose receptors are in the cell membrane.

Question 14

What do G proteins do?

Answer 14

Function as molecular switches, alternating between inactive GDP and active GTP states.

Question 15

What is the main function of epinephrine?

Answer 15

To increase the availability of glucose as a source of ATP for energy production.

Question 16

Fill in the blank: The sequence of events when epinephrine binds to a receptor includes the activation of _______.

Answer 16

adenylate cyclase

Question 17

What does cyclic AMP do?

Answer 17

Transmits the chemical message to protein kinase.

Question 18

What happens when epinephrine secretion stops?

Answer 18

Adenylate cyclase reverts to its inactive form and cAMP is no longer formed.

Question 19

What is the effect of cholera toxin on cAMP levels?

Answer 19

It causes abnormally high levels of cAMP in intestinal epithelial cells.

Question 20

How do caffeine and theophylline affect cAMP?

Answer 20

They inhibit phosphodiesterase, prolonging the action of cAMP.

Question 21

What are the three ways signal molecule levels are regulated in the blood?

Answer 21

• Rapidly inactivating circulating signal molecule
• Maintaining constant concentrations through synthesis and degradation
• Changing the rate of release from storage

Question 22

What is phosphorylation of cellular proteins?

Answer 22

A covalent modification that can activate or inactivate enzymes.

Question 23

What effect does phosphorylation have on glycogen phosphorylase?

Answer 23

It activates glycogen phosphorylase.

Question 24

What are prostaglandins?

Answer 24

Hormone-like substances produced from arachidonic acid that have numerous regulatory functions.

Question 25

What enzyme speeds up the production of prostaglandins?

Answer 25

Cyclooxygenase.

Question 26

What is the effect of NSAIDs like aspirin on cyclooxygenase?

Answer 26

They inhibit cyclooxygenase, reducing the production of prostaglandins.

Question 27

What are the two products released from the hydrolysis of phosphatidyl inositol-bisphosphate (PIP2)?

Answer 27

* Inositol triphosphate (IP3) * Diacylglycerol (DAG)

Question 28

What role do calcium ions (Ca2+) play in cell signaling?

Answer 28

They function as an important second messenger, regulating many cell functions.

Question 29

What induces the release of Ca2+ into the cytoplasm?

Answer 29

IP3 ## Footnote IP3 is a second messenger involved in the signaling pathways that regulate various cell functions.

Question 30

Why is Ca2+ considered an important second messenger?

Answer 30

Many cell functions are regulated by the concentration of Ca2+ in the cytoplasm ## Footnote Similar to cyclic AMP, Ca2+ plays a critical role in signaling processes.

Question 31

Where is the concentration of Ca2+ higher, in the cytoplasm or in the endoplasmic reticulum (ER)?

Answer 31

In the endoplasmic reticulum (ER) ## Footnote Ca2+ is actively transported out of the cytoplasm into the ER, maintaining lower levels in the cytoplasm.

Question 32

What is the role of inositol trisphosphate (IP3) in Ca2+ transport?

Answer 32

IP3 increases cytoplasmic Ca2+ concentration via signal-transduction pathways ## Footnote IP3 acts as a second messenger that facilitates the release of Ca2+ from the ER.

Question 33

What complex is formed when a signal molecule binds to its receptor?

Answer 33

Signal molecule-receptor-G protein complex ## Footnote This complex activates phospholipase C, which initiates the signaling cascade.

Question 34

What are the products of the enzymatic reaction catalyzed by phospholipase C?

Answer 34

IP3 and DAG ## Footnote These molecules are critical for further signaling processes in the cell.

Question 35

What is the function of DAG in signaling pathways?

Answer 35

DAG functions as a second messenger in other pathways ## Footnote While IP3 primarily increases Ca2+ levels, DAG serves different signaling roles.

Question 36

What is calmodulin?

Answer 36

A Ca2+-binding protein that mediates many Ca2+ stimulated enzymatic reactions ## Footnote Calmodulin plays a crucial role in various cellular processes by interacting with target proteins.

Question 37

How many Ca2+ ions can calmodulin complex with?

Answer 37

4 Ca2+ ## Footnote This ability allows calmodulin to effectively transmit signals related to Ca2+ concentration.

Question 38

What effect does the calmodulin-Ca2+ complex have on phosphodiesterase?

Answer 38

It stimulates phosphodiesterase activity ## Footnote This action decreases cAMP activity in many tissues.

Question 39

What happens when cytoplasmic Ca2+ levels increase?

Answer 39

The calmodulin-Ca2+ complex binds to the Ca2+-ATPase pump ## Footnote This stimulates the pump to transport Ca2+ out of the cytoplasm, normalizing Ca2+ levels.

Question 40

Fill in the blank: Calmodulin transmits the message carried by an increase in Ca2+ in the cytoplasm by forming a _______.

Answer 40

Ca2+-calmodulin complex ## Footnote This complex binds to specific Ca2+-regulated proteins to stimulate their activity.