BIO 360 - Exam 1 - Chapter 6 Signaling SP 2023 PowerPoint

Question 1

What is the Nernst Equation?

Question 2

How do cells talk to each other?

Answer 2

• electrical communication via gap junctions – direct
  cytoplasmic links between cells.
• chemical communication via neurotransmitters,
  hormones, paracrine factors, contact-dependent
  molecules.

Question 3

Major basis for classification is ______ over which
signal is transmitted.

Answer 3

distance

Question 4

Physiological signals
* ______ ______
Changes in the membrane potential of a cell
* ______ ______
Secreted by cells into extracellular fluid (ECF)
Responsible for most communication within the body
Chemical signals are ______.
* Target cells, or targets, respond to signals

Answer 4

Electrical signals / Chemical signals / ligands

Question 5

What is the role of gap junctions with direct contact and local cell-to-cell communication?

Answer 5

• Gap junctions transfer both chemical and electrical signals.
• They form direct cytoplasmic connections between adjacent cells.
  Local communication
• Gap junctions create cytoplasmic bridges
• Contact-dependent signals require cell-to-cell contacts,
• Cell Adhesion Molecules transfer signals in both directions

Question 6

Methods of cell-to cell communication
Local communication uses ______ and ______ signals.

Answer 6

Autocrine – same cell
Paracrine – different cells, close by

Question 7

The nervous system uses a combination of chemical
and electrical signals for long-distance cell-to-cell
communication.
______ are chemical signals secreted by neurons
______, ______, ______.

Answer 7

Neurocrines / Neurotransmitters, Neuromodulators, Neurohormones

Question 8

______ are chemicals secreted by neurons that diffuse across a small gap to the target cell. ______ use electrical signals as well.

Answer 8

Neurotransmitters / Neurons

Question 9

Signal pathway - When does a cell responds to a particular chemical signal? What is an example of this?

Answer 9

Only if the target has a receptor, a binding protein.
Hormones are secreted by endocrine glands or cells into the blood. Only target cells with receptors for the hormone will respond to the signal.

Question 10

What is the signal pathway?

Answer 10

The signal pathway:
* The chemical signal is a ligand that binds to the
receptor and is the first messenger
* Ligand-receptor binding activates the receptor
* The receptor activates one or more intracellular
signal molecules
* The last signal molecule modifies existing proteins or
initiates the synthesis of new proteins

Question 11

Signal Pathways: Receptor locations
* ______ signal molecules diffuse through the cell membrane
Bind to receptors in the ______ or nucleus.
* ______ signal molecules bind to receptors on the cell
membrane.

Answer 11

Lipophilic / Lipophobic / cytosol

Question 12

What are the four groups of membrane receptors?

Answer 12

• G protein-coupled
• Receptor-enzymes
• Integrin receptors
• Ligand-gated

Question 13

Transmission of signal from one side of the membrane to
the other is called _______ ______.

Answer 13

signal transduction

Question 14

______ ______ allows a small amount of signal to have a large effect. One ______ is ______ into many intracellular molecules.

Answer 14

Signal amplification / ligand / amplified

Question 15

Figure 6.6c - Signal Transduction: Cascades and
Amplification

Answer 15

cAMP

cGMP

Question 16

How does a receptor produce a 2nd messenger
inside cell?

Answer 16

• Agonist binds to recognition site on plasma membrane and
  activates receptor (R*)
• R* activates a transduction molecule, e.g. often a G protein
• G protein* transfers signal to cell interior by interacting with
• Effector molecule - often enzymes that catylize reactions in the cell.

Question 17

What is the difference between an agonist and antagonist ligand?

Answer 17

Agonist – ligand that activates the receptor
Antagonist – ligand that blocks the receptor

Question 18

Many receptors use a ___ ______ for signal transduction Proteins that bind GTP (guanosine triphosphate).

Answer 18

G protein

Question 19

cAMP made from ATP - reaction catalyzed by effector enzyme ______ ______ cytoplasmic side of plasma membrane.

Answer 19

adenylyl cyclase

Question 20

cAMP activates…

Answer 20

protein kinase A (PKA)

Question 21

What are kinases?

Answer 21

transfer phosphate group from ATP to a protein

Question 22

What two things are a major determinant of protein activity?

Answer 22

cAMP-dependent PKA phosphorylates & intracellular proteins

Question 23

What removes phosphates from proteins?

Answer 23

Phosphatases

Question 24

Card 30-37 in Powerpoint

Question 25

Card 38 Figure 6.6c Signal Transduction: Cascades and
Amplification

Question 26

Card 40-43

Question 27

______ Is an Important Intracellular Signal.
* Enters through ______ ______.
* Calcium is stored inside the ______ ______.
* Released from ______ messengers

Answer 27

Calcium / gated channels / endoplasmic reticulum / second

Question 28

Card 48-53