Unit 1: Cell signaling

Question 1

what is cell signaling?

Answer 1

communication within and between cells

Question 2

what is signal reception?

Answer 2

selective response defined by receptors on the receiving cell (AKA target cell).

Question 3

the signal may potentially be distributed to every cell of the body, but only ______ cells will respond to it.

Answer 3

target cells

[they are effectively tuned in to receive signal]

Question 4

What are the 3 primary cell signaling mechanisms?

Answer 4

1. direct cell to cell -typically with a gap junction [rare]
2. chemical [most common] between cells
3. electrical [signaling within cell]

Question 5

what is the most common cell signaling mechanism?

Answer 5

chemical

Question 6

_________ signals are where a cell literally produces a signal that acts on the cell that produced it

Answer 6

autocrine

Question 7

________ signals can produce a signal that acts on cells that are very close-by

Answer 7

Paracrine

Question 8

________ signaling is used almost exclusively for intracellular signaling

ex) signal transmission within a neuron)

Answer 8

electrical

Question 9

__________ signaling is very fast and localized/ target-specific

Answer 9

electrical

Question 10

_________ signaling could take several circulations to reach the correct target, so may be slow, broad spectrum of cells reached

Answer 10

chemical

Question 11

In the receptor second messenger pathway, the first step is the ____[1]_______ binds to G-protein linked receptor, which activates the ______[2]_______

Answer 11

1] signal molecule

2] G protein

Question 12

Step 2 of receptor second messenger pathway [G protein coupled receptors]

G protein turns on _________________, an amplifier enzyme

Answer 12

adenylyl cyclase

Question 13

Step 3 of the receptor second messenger pathway [G protein coupled receptors]

Adenylyl cyclase converts ATP to:

Answer 13

cyclic AMP

Question 14

Step 4 of the receptor second messenger pathway [G protein coupled receptors]

cAMP activates:

Answer 14

protein kinase A

Question 15

Step 5 of the receptor second messenger pathway [G protein coupled receptors]

protein kinase A phosphorylates other proteins, leading ultimately to :

Answer 15

a cellular response

Question 16

Step 1 of phospholipase C Coupled second messenger system

_____[1]____ activates receptor and associated ____[2]_____

Answer 16

1] Signal molecule

2] G protein

Question 17

Step 2 of phospholipase C Coupled second messenger system

G protein activates __________________ ,an amplifier enzyme

Answer 17

phospholipase C (PL-C),

Question 18

Step 3 of phospholipase C Coupled second messenger system

PL-C converts membrane phospholipids into____________________, which diffuses into the cytoplasm

Answer 18

IP3- [inositol triphosphate]

Question 19

Step 4 of phospholipase C Coupled second messenger system

IP3 [inositol triphosphate] causes release of :

Answer 19

Ca2+ from organelled, creating a Ca2+ signal

Question 20

in the phospholipase C Coupled second messenger system, the second messenger is the

Answer 20

calcium

[but also arguably IP3 as well]

Question 21

simple chemical VS electrical signal pathways

Answer 21

Question 22

Signal amplification is a property of _______ transduction pathways.

Answer 22

second messenger

Question 23

ATP is the substrate that interacts with adenylyl cyclase, activated adenylyl cyclase catalyzes the conversion of ATP into :

Answer 23

cAMP

Question 24

Indirect receptor channel and second messenger transduction pathways have what in common?

Answer 24

G-protein couple receptors
G-proteins

Question 25

The _____________ , not the cellular signal, determines the response to a cellular signal.

Answer 25

target cell

Question 26

The image depicts a second messenger transduction pathway. Identify the step/component labeled B:

Answer 26

adenylyl cyclase enzyme

Question 27

The affinity of a receptor for its ligand is a measure of the:

Answer 27

strength of binding between ligand and receptor

Question 28

The image depicts a second messenger transduction pathway. Identify C

Answer 28

G-protein

Question 29

In the cAMP second messenger transduction pathway, ATP is used as:

Answer 29

a precursor for conversion into cAMP

Question 30

_______________ is the sum of the atomic weights of the constituent atoms

Answer 30

Molecular weight

Question 31

1 mole =

Answer 31

6.022 x 10^23 [avogadro's #]

Question 32

Molarity =

Answer 32

moles of solute in one liter of solution

Question 33

In a gas-liquid or solid-liquid solution the _________ is defined as the solvent

Answer 33

liquid

Question 34

In a liquid-liquid solution, the liquid present in greater amount is the :

Answer 34

Solvent

Question 35

_______ is the non-solvent component of a solution

Answer 35

solute

Question 36

A _________ is a transparent and uniform mixture of 2+ molecules (solvent and solute) that will not separate spontaneously

Answer 36

solution

Question 37

Define “ligand”.

Answer 37

could be cell signal substrate whole host of molecules that can act as a key

Question 38

Describe the different ways in which hydrophobic and hydrophilic ligands interact with target cells [[[chemical signaling]]]

Answer 38

Hydrophobic [membrane permeable]- will be transported to target cell and move through membrane; in cell, they bind to something so they can stay. Generally, signal will usually act on nucleus and alter reading of genetic instructions Hydrophilic [membrane impermeable]- don't need carrier, but trapped outside membrane of target cell; requires a transduction step

Question 39

Define “transduction”.

Answer 39

relaying message across the membrane Signal transduction is the process by which an extracellular signal molecule activates a membrane receptor that alters intracellular molecules to create a response

Question 40

Define “amplification”.

Answer 40

one extracellular signaling molecule binding to one G protein-coupled receptor will activate one single adenyl cyclase enzyme within the membrane, but that one enzyme has the potential to convert multiple ATP molecules into cyclic AMP ~one signal molecule is turned into multiple 2nd messenger molecules

Question 41

How are signaling pathways turned off?

Answer 41

Signaling processes have built-in termination mechanisms Receptor activity is stopped in various ways: ~Extracellular ligand can be degraded by enzymes ~Endocytosis of receptor-ligand complex can also terminate activity

Question 42

Mechanisms of cell signaling- Describe cell-to-cell method:

Answer 42

~Cells are literally connected to eachother, typically in the form of a gap junction ~relatively rare form of signaling, but abundant in the heart, smooth muscle cells, sometimes in nervous system ~Gap junctions create cells that share 1 continuous membrane [Rare; focus more on the common forms of cell signaling]

Question 43

Mechanisms of cell signaling- describe the chemical signaling method:

Answer 43

~Most common method of cell signaling ~between cells, also between organisms [ex- skunk]

Question 44

Mechanisms of cell signaling- electrical signaling method is restricted to-

Answer 44

~restricted to signaling within a cell, not between seperate cells

Question 45

Cell signaling can be categorized by Range: ________ or ________ and Mode: __________ or _________

Answer 45

Range- how far the signal travels: Local (adjacent cells) or Long distance Mode- form of signal while in transit: Chemical or electrical

Question 46

3 types of local cell signaling include-

Answer 46

1) gap junctions (electrical or chemical) 2) contact-dependent signals (chemical) 3) Autocrine & paracrine signals (chemical)

Question 47

Electrical signaling is mainly the domain of the:

Answer 47

Neuron

Question 48

The electrical signal is the resident of

Answer 48

THE CELL does not move beyond the cell

Question 49

When electrical signals take place in the axons, they are called:

Answer 49

action potentials

Question 50

[chemical signaling] - 2 ligand types Hydrophobic ligand is _______________ Hydrophilic ligand is ____________

Answer 50

Hydrophobic ligand is membrane permeable Hydrophilic ligand is membrane impermeable

Question 51

the signal molecule is a ____1____ that binds to a protein receptor. The ligand is also known as a first messenger because it brings information to ________2_______

Answer 51

1- ligand 2- the target cell

Question 52

Define “receptor”

Answer 52

protein molecule that contains a binding site for another specific molecule (called a ligand)

Question 53

What determines the function of a signal molecule?

Answer 53

Various factors (?) Structure (???)

Question 54

How are transduction pathways turned off?

Answer 54

Various ways Cell surface receptors can become desensitized to a ligand

Question 55

Diagram a basic/generalized signaling pathway.

Answer 55

1. Signal Molecule binds to a membrane receptor protein 2. The membrane receptor protein activates intracellular signal molecules. 3. The Intracellular signal molecules alter target proteins 4. The target proteins create a response.

Question 56

Diagram and describe the steps in a cAMP second messenger pathway.

Answer 56

1) signal molecule binds to G protein linked receptor, activating G protein 2) G protein turns on Adenylyl cyclase (an amplifier enzyme) 3) Adenylyl cyclase converts ATP into Cyclic AMP (cAMP) 4) cAMP activates protein kinase A 5) Protein kinase A phosphorylates other proteins, leading to cellular response

Question 57

Diagram and describe the steps in a phospholipase-C second messenger pathway.

Answer 57

1) signal molecule activates the receptor and associated G protein 2) G protein activates phospholipase C (Pl-C, an amplifier enzyme) 3) Pl-c converts membrane phospholipids into ip3, which diffuses into cytoplasm 4) Ip3 causes release of calcium from organelles, creating a calcium signal