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Cell Biology (grad) > Cell Signaling > Flashcards

Cell Signaling Flashcards

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1
Q

*What is the associated effector and 2nd messenger for Gs alpha protein?

A

Gs protein:
Effector: stimulation of Adenyl cyclase
2nd Messenger : cAMP (increased)

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2
Q

*What is the associated effector and 2nd messenger for Gi alpha protein?

A

Gi protein:
Effector: inhibition of Adenyl cyclase
2nd Messenger: cAMP (decreased)

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3
Q

*What is the associated effector and 2nd messenger for G-olf alpha protein?

A

G-olf alpha protein:
Effector: activates Adenyl cyclase
2nd Messenger: cAMP (increased)

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4
Q

*What is the associated effector and 2nd messenger for Gq alpha protein?

A

Gq protein:
Effector: Phospholipase C
2nd Messenger: IP3, DAG (increased)

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5
Q

*What is the associated effector and 2nd messenger for G o alpha protein?

A

G o protein:
Effector: Phospholipase C
2nd Messenger: IP3, DAG (increased)

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6
Q

*What is the associated effector and 2nd messenger for G t alpha protein?

A

Gt protein:
Effector: cGMP phosphodiesterase
2nd Messenger: cGMP (decreased)

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7
Q

Name some of the cell responses that are mediated by cyclic AMP, including the extracellular signal and target tissue

A
  1. Extracellular signal: Adrenaline
    Target tissue: Heart
    Response: increase in heart rate and force of contraction
  2. Extracellular signal: Adrenaline
    Target tissue: Skeletal muscle
    Response: glycogen breakdown
  3. Extracellular signal: Adrenaline and glucagon
    Target tissue: Fat
    Response: breakdown of fat
  4. Adrenocorticotropic Hormone (ACTH)-
    Target tissue: Adrenal gland
    Response: cortisol secretion
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8
Q

increase in heart rate, glycogen breakdown, fat breakdown and cortisol secretions are all cell responses mediated by which secondary messenger?

A

cyclic AMP

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9
Q

Which cell responses are mediated by secondary messenger Phospholipase C?

A

glycogen breakdown, secretion of amylase (digestive enzyme), contraction and aggregation.

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10
Q

describe the cell responses mediated by Phospholipase C activation and be sure to include signal molecules, target tissue and major response.

A
  1. signal Molecule: Vasopressin (peptide hormone)
    Target tissue: Liver
    Response: glycogen breakdown
  2. signal Molecule: Acetylcholine
    Target tissue: pancreas
    Response: secretion of Amylase (digestive enzyme)
  3. signal Molecule: Acetylcholine
    Target tissue: smooth muscle
    Response: contraction
  4. signal Molecule: Thrombin (proteolytic enzyme)
    Target tissue: blood platelets
    Response: aggregation
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11
Q

Describe the special case for effector K+ channel and include which G proteins regulate the effector and it’s response.

A

K+ channel is the associated effector.
G alpha, G beta and G gamma proteins all regulate the effector K+ channel
induces response: change in membrane potential

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12
Q

what process can be described as “At the core of life” ?

A

Cell communication- at the core of life.
Many cells communicate and work together for functions of surviving, dividing and differentiating.
Without the existence of cells, no one would be able to live (dead).

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13
Q

What happens to cell’s core of life with the development of a disease?

A

A disease disrupts normal cell signaling (interactions between cells)
Hence if you understand, network and signals, you can correct and control the signals if necessary.

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14
Q

What occurs during signal transduction?

A
  1. Signal 2. Reception 3. Cell’s response
    Signal (from environment, or outside cell) reaches cell.
    Cell receives the signal, and will create a cellular response to signal.
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15
Q

In signal transduction, what is needed to receive the signal? what is the cell that has the receptors?
What happens if the

A

Receptor needed to receive signal

Target cell- has receptors.

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16
Q

What is signal transduction?

A

process of transmitting a signal to a cell to generate a cellular response
involves converting one signal into another signal.

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17
Q

Describe the example of signal transduction using a phone, and be sure to include target cell, intra/extracellular signal.

A

When you get a call from a friend, the phone (target cell) will convert radio signal, which travel in the air to a sound wave, which you will hear on the phone when listening to friend talk.
The radio signal IN the phone will be come OUT as Sound signal.

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18
Q

What is the difference between the extracellular signals and intracellular signals in cells?

A

The MEMBRANE between the two signals.

The extracellular signal will come into membrane and be converted out as a intracellular signal.

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19
Q

what happens if a ligand does not bind to a receptor? what happens if cell does not have a receptor for particular ligand?

A

NO CELLULAR RESPONSE, if ligand does not bind to receptor.

if cell has no receptors for a certain ligand (example X), it is NOT a target cell.

20
Q

differentiate between the type of molecules used for cell-surface receptors vs intracellular receptors.

A

large, Hydrophilic signal molecules bind to cell surface receptors.
small, hydrophobic signals easily bind to intracellular receptors.
signals maybe transmitted from carrier proteins.

21
Q

What happens to the budding yeast in response to mating factor or pheromone released in culture?

A

in response to pheromone, the yeast cells will become elongated (change shape from round to elongated)
the elongated shape, is due to yeast making more phospholipids (happens fast)

22
Q

Explain the list of events that occur when a cell responds to a signal. provide examples.

A 
When an extracellular signal binds to receptor, it will be converted into intracellular signal
effector proteins (ex: metabolic enzyme, cytoskeletal protein) will then receive intracellular signal and target cell will respond. 
Ex: signal that bind to receptor can alter metabolism, alter cell shape and movement or alter gene expression
23
Q

Differentiate between the signaling response speed in protein function versus protein synthesis.

A

Signaling responses that occur FAST (secs to mins) can alter protein function, through intracellular signaling however
to alter protein synthesis (like transcription of developmental processes), it will be SLOW (mins to hrs) and take a long time to occur (using cell-surface receptor proteins)

24
Q

What are the 4 types of signaling ? Describe the signaling processes that occur in each case. Which types of signaling are up close, vs at a distance?

A

Contact-dependent- receptor at cell’s surface that signal can bind to
Paracrine signals will activate target cells nearby
Synaptic -electric signal travel down axon, along terminal then convert to chemical and go to synaptic cleft
Endocrine- signal molecules travel into blood stream to eventually reach target cells.
contact-dependent and paracrine are up close signals;
while synaptic and endocrine (longest distance) are long distance

25
Q

What is a gap junction and how does it affect the cell? How does it affect both cells?

A

Gap junction- tube that connect 2 different cells.

What ever happens to one cell will happen to the other cell

26
Q

What kind of signaling is autocrine signaling? Provide an example

A

Autocrine signaling is a form of paracrine signaling,
where cells respond to the local mediators or signals that they produce themselves.
coordination of groups of identical cells, each cell will receive a strong autocrine signal.
autocrine signals generate a lot of signals in short time frame.

27
Q

Describe the concept behind Negative feedback and positive feedback. What’s an example of negative feedback?

A

Negative feedback: if you have enough of product, you can inhibit production of reactant or substrate (regulation)
Positive feedback: to produce more of a product, you can add more of the reactant or substrate
signal kinase will phosphorylate and activate an enzyme kinase.
Then eventually negative feedback will allow phosphatase to remove phosphate from initial enzyme (that was activated)
and will inactivate enzyme

28
Q

describe the concept of smooth muscle relaxation and contraction in terms of lumen of blood vessel. What is the purpose of lumen of blood vessel? what happens to lumen when muscle contracts?

A

The lumen of blood vessel is a cavity through which blood flows.
presence of acetylcholine will allow muscles to contract, which makes lumen of blood vessel become smaller.
meanwhile, when muscle relaxes, lumen becomes larger.

29
Q

What two compounds lead to relaxation of muscles? what other compounds must be activated for muscle relaxation to occur?

A

Acetylcholine and Viagra both lead to relaxation of muscles (larger lumen)
Acetylcholine binds to receptor, activate phospholipase C which activates IP3, eventually NO, binds to receptor and activate guanylate cyclase (protein kinase G) which leads to relaxation.

30
Q

Differentiate between a reaction with no scaffold protein, vs a reaction with a scaffold protein? what occurs?

A

a reaction with signal bound to receptor and scaffold will make reaction occur faster, while reaction without scaffold will take a longer time to occur, and require more energy.

31
Q

What are the two main examples of molecular switches? distinguish between GAP and GEF

A

signaling by protein phosphorylation and GTP binding proteins.
protein phosphorylation:
- protein kinase will hydrolyze ATP and form ADP which will turn signal on. Phosphorylation also changes shape.
-protein phosphatase will form bind gdp and form gtp which will turn signal off.

GTP binding proteins:
When you bind GTP (lead to GDP) signal will turn on (phosphorylate- conformation change)
When you hydrolyze GTP (bind GDP) you will remove phosphate and turn SIGNAL OFF.
GAP- GTPASE activating protein- give up GTP faster (GTP hydrolysis) turn off signal
GEF- GTP-GDP exchange factor- hold on to GTP longer (in exchange for GDP) turn on signal

32
Q

What are the different types of cellular receptors?

A

Gated Ion channel- signal bind to receptor to allow ions go through channel
enzyme linked receptors,
G-protein linked receptors,- signal bind to receptor which will activate g protein, G protein eventually bind to enzyme and activate enzyme
Enzyme-associated receptors
Steroid receptors.

33
Q

Distinguish between Non-NMDA and NMDA receptor? What does one receptor have that other does not?

A

Non-NMDA- only has binding site for glutamate

NMDA has binding site for glycine and Glutamate (excitatory)

34
Q

Describe G protein-linked receptors.

What are the three components of G-protein receptor that automatically turn off?

A

G protein receptors are:
-largest family of cell surface receptors
transmit signals via guanine nucleotide binding proteins
functional diversity (receptor for neurotransmitter, hormone,, responsible for smell, taste and sight
similar structure
G proteins activate chain of events that alter concentration of one or more secondary messengers
3 components : receptor, G protein (alpha, gamma, beta), effector

35
Q

What happens when hormone signal binds to receptor in g protein?

A

Hormone bind to receptor, create confirmational change in receptor,
activated receptor binds to G alpha subunit
binding induces change in G alpha, bound GDP dissociates and becomes GTP; G alpha dissociates from Gbetagamma.
Eventually, hormone unbinds from receptor, G alpha binds to effector, activating it
Hydrolysis of GTP to GDP causes G alpha to dissociate from effector and reassociate with Gbeta gamma.

36
Q

What are secondary messengers?

A

small intracellular molecules that act on intracellular proteins.
example: effector adenyl cyclase will activate secondary messenger cAMP.
example of secondary messengers:
1. Cyclic AMP and Calcium (most common)
2. Cyclic GMP
3. Diacyl Glycerol
4. phosphoinotol diphosphate
cycilc AMP activates protein kinase which ten activate and phosphorlates trancription regulator.

37
Q

Discuss the importance of Calcium.

A

Calcium is very important intracellular messenger
necessary for variety of cellular responses
concentration changes from nanomolar to micormolar depending on type of cell and cell state
increase in Ca triggered by fertilization (increase in Ca from egg)
Calcium seen in food like dairy products, green veggies, salmon, sardines

38
Q

Differentiate between Na+ driven Ca exchanger and Ca pump?

A

Na driven calcium exchanger does not need energy for sodium to enter inside cell in exchange for Ca out
Calcium pump requires ATP and phosphorylation of receptor to allow calcium to come out.
calcium pump in ER, ca bind to molecules in cytoplasm and calcium actively transported to mitochondria (no need for ATP)

39
Q

What is relationship between calcium and vasopressin?

A

As you increase the concentration of vasopressin, the elevation of calcium gets lower (frequency of elevation shrinks)

40
Q

What are the calcium binding proteins and calcium sensor proteins?
What are the EF hands?

A

Calcium binding proteins: troponin C and Calmodulin
Calcium sensor proteins: s100B, GCAPS, Nuerocalcin
EF hands- domain that binds calcium.

41
Q

What happens to K+ channels when G proteins dissociate from receptor?

A

When G protien (alpha, gamma, beta) dissociate from receptor, K+ channels close, and GTP goes to GDP, lose phosphate.

42
Q

How is Protein kinase C activated? How do DAG and IP3 play a role?

A

Signal molecule binds to receptor activate g protein
G protein then activates Phospholipase C which produces inositol phospholipid (DAG And IP3)
DAG binds to protein kinase C, while calcium also binds to pKC which activates it.
Calcium came from phosphorylation of calcium channel by IP3 phosphorylating channel.

43
Q

What are two examples of enzyme coupled receptors?

A
  1. A signal molecule can bind to 2 catalytic domains which can activate each other (receptor can be enzyme)
  2. Signal molecule can bind to receptor that has an associated enzyme, which will be activated.
44
Q

What happens when you phosphorylate Bad protein? What happens to Bcl2?

A

When Bad phosphorylated it will release active form of Bc12 which promotes cell survival (prevents inhibition)
Phosphorylated Bad becomes inactive

45
Q

What are examples of signaling proteins?

What unique structure does universal estrogen receptor have?

A

Signal for hormones: cortisol, estradiol, testosterones, thyroxine
signal: vitamins: vitamin D3, retinoic acid
estrogen receptor has zinc fingers that are used to grab promoter of DNA.

46
Q

Explain the role of Notch and Delta protein?

A

Notch begins in Golgi and transported to PM, where Notch binds to delta, cleaved twice and notch tail migrates to nucleus (total of 3 cleavage sites) where tail binds to protein and activates transcription of genes.

47
Q

Differentiate between how the presence or absence affects transcription.

A

Absence of ethylene- ethylene receptor will be active, protein kinase active which leads to degradation of transcription regulator and ethylene responsive genes OFF.
Presence of ethylene- ethylene receptor is inactive, protein kinase inactive, which will activate transcription regulator and turn on ethylene responsive genes.

Cell Biology (grad) (16 decks)

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