Cell Signaling 1

Question 1

What kind of signaling is this? How does it work?

Answer 1

Question 2

What kind of signaling is this? How does it work?

Answer 2

Question 3

What kind of signaling is this? How does it work?

Answer 3

Question 4

Define what a ligand is.

Answer 4

A signaling molecule.
A molecule that binds to another specific molecule, usually a receptor on a cell, to trigger a cellular response, essentially acting as a chemical messenger that transmits signals between cells within an organism.
Ligand = Key
Receptor = Lock

Question 5

What are second messengers?

Answer 5

Intracellular signaling molecules.

Question 6

Can you fill in the blanks?

Answer 6

Question 7

Receptor binding initiates __________ inside the cell.

Answer 7

Signal transduction

Question 8

What is the concentration of calcium in a cell?

Answer 8

About 100nm or 0.0001 mM

Question 9

Why is calcium kept low in the cell?

Answer 9

Because calcium is an important second messenger.

Question 10

How was calcium kept low in the cell?

Answer 10

Through Ca++-ATPases that pump calcium out of the cell or into the endoplasmic reticulum. (or sarcoplasmic reticulum in muscle cells.)

Question 11

What are the two ways calcium concentration in the cytosol can increase?

Answer 11

1. Ca++ can enter via a membrane calcium channel(from outside the cell to inside).
2. Ca++ can be released from intracellular stores. (Endoplasmic reticulum or sarcoplasmic reticulum.)

Question 12

What is Calmodulin? How does it work?

Answer 12

A ubiquitous Ca++ binding protein.

Question 13

Besides calmodulin what are two other important Ca++ binding proteins? What do they do?

Answer 13

Troponin (regulation of skeletal muscle contraction)
Proteins involved in exocytosis

Question 14

Test: fill in the blanks.

Answer 14

Question 15

True or false: all receptor proteins are found on the membrane. If false, name the types.

Answer 15

False: most are(polar signaling molecules), BUT some can diffuse across the membrane(Nonpolar signaling molecules)
Polar= Cell membrane receptor
Nonpolar = Intracellular Signal Receptor

Question 16

Where is the receptor for a lipophilic signal molecule?(2)

Answer 16

1. In cytosol
2. In nucleus: Nuclear receptors
   They are intracellular receptors!

Question 17

What is the main difference between lipophilic signal molecules + intracellular receptors and extracellular signal molecules + cell membrane receptors?

Answer 17

Intracellular signaling= slow responses related to changing gene activity. (Think hormones/mood)
Cell membrane signaling= Rapid cellular response.

Question 18

What are the categories of membrane receptors? (3)

Answer 18

Question 19

Nuclear receptors function as a ligand-activated transcription factors. Explain what that means.

Answer 19

Ligand is signal, receptor is transcription factor. So when ligand binds to nuclear receptor it changes gene expression.

Question 20

Nuclear receptors have a characteristic modular structure. What is it?

Answer 20

Question 21

When the ligand isn’t available for the nuclear receptor, what is its dormant state and where is it?

Answer 21

Its dormant state usually has some type of inhibitory complex. Keeps receptor in the cytoplasm, the binding of the ligand is what allows it to travel to the nucleus. And interact with coregulatory complexes to change gene expression in some way.
It will take a while!

Question 22

Test: fill in the blank

Answer 22

Question 23

Can you name all 8 Nonpolar hormones that signal via intracellular receptors. (They are all Nonpolar )

Answer 23

Question 24

Name the 6 steroid hormones that signal via intracellular receptors.

Answer 24

Estrogen
Progesterone
Testosterone
Aldosterone
Cortisol
Vitamin D (1,25(OH)2D)

Question 25

Name the two thyroid hormones that signal via intracellular receptors.

Answer 25

Triiodothyronine (T3) Thyroxine (T4)

Question 26

What is special about drugs targeting intracellular receptors? Can you give examples?

Answer 26

They can be administered topically. The advantage to this is that it targets the treatment area, allowing lower dosage and avoiding the side effects that can occur when these drugs are admitted stirred systematically. Ex. Inhaled glucocorticoid drugs for asthma. Skin creams, and ointment (containing glucocorticoids) for eczema, testosterone gel to treat low testosterone levels.

Question 27

Explain how ligand-gated ion channels work. What’s the usual signaling molecule?

Answer 27

Binding of the signaling molecule opens the channel, creating a change in membrane potential that occurs within a few milliseconds. This is the signaling mechanism that underlies **fast synaptic transmission**. Usually a neurotransmitter is the signaling molecule.

Question 28

Test: fill in the blanks and what type of channel is this?

Answer 28

Ligand gated ion channel.

Question 29

Test: fill in the blanks. What ions increase hyperpolarization? depolarization?

Answer 29

Question 30

Where do you see nicotine acetylcholine receptors? (AChR)

Answer 30

In the brain. Important: Neuromuscular Junction and synapsis in autonomic ganglia.

Question 31

Define neuromuscular junction.

Answer 31

The synapsis between a somatic motor neuron. In other words, a neuron in your spinal cord that controls muscle contraction. Synapsis between the neuron and the skeletal muscle cell .

Question 32

Test: fill in the blanks.

Answer 32

Question 33

There is fast and slow synaptic transmission. What speed are ligand-gated channels? What about g-protein coupled receptors?

Answer 33

Ligand-gated Channels = Fast G-protien receptors = Slow

Question 34

G-Protein Knowledge: what it is made of.

Answer 34

Question 35

What is a G-Protein? (Generic)

Answer 35

A protein that binds GTP to become activated.

Question 36

G-Protein Knowledge: how it functions.

Answer 36

Question 37

Test: fill in the blank.

Answer 37

Question 38

Test: G-Alpha, fill in the blank.

Answer 38

Question 39

cAMP activates protein kinase A (PKA). Why does this matter?

Answer 39

Question 40

The GPCR signal is terminated at several steps. What are the steps?

Answer 40

Question 41

Do you know how cholera works?

Answer 41

Adding on: increased fluid secretion is because CFTR is open too often due to phosphorylation, meaning ions go out of cell into places like GI tract. Meaning water follows suit(through osmosis), leaving your body.

Question 42

cAMP can do more than work through protein kinase A. What else can they do? Give an example of how it occurs? Hint: Golf.

Answer 42

It can change membrane potential and act as a ligand to open ion channels.