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BIO 202 > Cell Communication and Signaling > Flashcards

Cell Communication and Signaling Flashcards

1
Q

Yeast Mating Types

A

Two types of haploid yeast (mating types)

1) Type a –> Secretes a-factor
2) Type alpha –> Secretes alpha-factor

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2
Q

Type-a yeast

A

Secretes a-factor

Has receptors for alpha-factor

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3
Q

Type-alpha yeast

A

Secretes alpha-factor

Has receptors for a-factor

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4
Q

Yeast Mating Process

A

1) a and alpha yeast cells bind to each others’ particles

2) a and alpha cells begin to fuse

3) creates a new cell with both a/alpha genes

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5
Q

Signal-Transduction Pathway

A

1) Signal reception
2) Signal transduction
3) Cell response

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6
Q

Types of communication in multicellular organisms (2)

A

1) Local communication
2) Long-distance communication

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7
Q

Types of local communication (3)

A

1) Paracrine
2) Direct Contact
3) Synaptic

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8
Q

Direct Contact Communication (and types)

A

Signals pass through intercellular connections OR through cell-cell recognition

1) Gap junctions
2) Plasmodesmata
3) Cell-cell recognition (involves glycoproteins)

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9
Q

Paracrine Communication

A

Signals released into the extracellular fluid (Signal is available to all neighboring cells)

–> Signal only impacts those target cells with the necessary receptor

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10
Q

Synaptic Communication

A

In NEURONS

–> Signals are released into a synapse (region between two neuron terminals)

–> Signal goes ONLY to interact with that one neuron (no other cells can interact with it)

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11
Q

Long Distance Communication (and its one type)

A

Occurs between cells that are farther apart (usually within an organism) –> BUT it can occur between organisms

1) Endocrine/Hormonal Signaling

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12
Q

Endocrine/Hormonal Communication

A

Signals are released by an endocrine cell and travel a long distance through a vascular system (or possibly through the air)

–> Only target cells with necessary receptors will respond

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13
Q

Fruit ripening when next to other ripe fruit is an example of…

(and explain its cause)

A

Long distance communication BETWEEN organisms

–> The ripening agent ETHYLENE (gas) that spreads to other fruits nearby a ripening fruit (gets them to ripen as well)

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14
Q

The ability of a cell to respond to a signal is dependent upon…

A

Whether it has the specific receptor molecule that can bind a given signal

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15
Q

Main stages of cell signaling (3)

A

1) Reception
2) Transduction
3) Response

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16
Q

Reception

A

The detection (by a target cell) of a signal which binds to a receptor molecule –> The RECEIVING of a signal

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17
Q

Receptor

A

Molecule that a signal binds to

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18
Q

Ligand

A

Signal Molecule

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19
Q

Main types of receptors (4)

A

1) G-protein linked receptor

2) Tyrosine-kinase receptor (enzyme receptor)

3) Ligand-Gate Ion Channel

4) Internal/Intracellular Receptor

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20
Q

G-Protein Linked Receptor

A

Cell surface transmembrane receptor that works WITH the help of G-protein

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21
Q

G-Protein

A

A protein that binds to GTP

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22
Q

G-Protein Linked Receptor: Extracellular Domain is ________

A

The receptor: Interacts with the ligand

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23
Q

G-Protein Linked Receptor: Cytoplasmic Domain is ________

A

Initiator of transduction: Interacts with the G-protein molecule

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24
Q

G-Protein Linked Reception Process

A

1) No ligand = Inactive state = G-Protein bound to GDP

2) Ligand binds to receptor: receptor changes shape

3) Inactive G-protein binds to receptor which causes GTP to displace GDP

4) Activated G-protein dissociates from receptor and diffuses along membrane

5) G-protein binds to an enzyme, activates it = triggers cascade

6) G-protein hydrolyzes GTP to form GDP and returns to inactive state

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25
Q

G-Protein Active vs Inactive states

A

Active State = Bound to GTP

Inactive State = Bound to GDP

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26
Q

Enzyme Receptors

A

Receptors that function as BOTH a receptor and an enzyme

(Not linked to an enzyme, it IS an enzyme)

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27
Q

Tyrosine-Kinase Receptor

A

Protein kinase receptor that phosphorylates tyrosine

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28
Q

Tyrosine-kinase receptor has ______ subunits

A

2 subunits

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29
Q

Tyrosine-Kinase Receptor Process

A

1) Signals bind to receptors of the TKR subunits

2) The subunits dimerize (come together to form one unit)

3) Subunits phosphorylate each other (their tyrosine components)

4) TK receptor FULLY activates

5) Relay proteins bind to the TKR and become activated = begins cascade

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30
Q

Protein Kinase

A

An enzyme that catalyzes the transfer of phosphate groups from ATP to another protein

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31
Q

Where do protein kinases get their phosphate group from?

A

Take it from ATP to give to other molecule

32
Q

Tyrosine-Kinase Receptors are associated with what disease? Why?

A

Cancer

–> TKRs are involved with a lot of growth factors so any issues with these receptors could cause uncontrolled growth = cancer

33
Q

Ligand-Gated Ion Channel

A

A type of membrane channel receptor which contains a region that can act as a “gate”

–> Channel “opens” when ligand binds

–> Channel is “closed” when no ligand binds

34
Q

How does Ligand-Gated Ion Channel lead to a cell response?

A

The channel allows for the passage of ions (if activated)

–> So a change in ion concentration when activated leads to the cellular response mechanisms

35
Q

Internal Receptors

A

(AKA intracellular receptors)

–> Receptors found INSIDE the cell

36
Q

Internal receptors only work if…

A

the signal can get INTO the cell

37
Q

Internal receptor signals include: (2)

A

1) Hydrophobic molecules (Ex: steroids/hormones)
2) Small gaseous molecules (Ex: ethylene)

38
Q

Testosterone signaling is an example of what…

A

Internal Receptor Signaling

–> Testosterone is a hormone that can enter the cell

–> Its receptor is found within specific cells which when activated lead to the development of male sex characteristics

39
Q

Transduction

A

Change to the receptor due to the binding of a signal which begins a sequence of biochemical events (pathway/cascade) which ultimately leads to a cellular response

40
Q

Analogy for transduction

A

Signal = Mailman

–> Signal “knocks on the door, leaves a letter, and then goes away”

41
Q

Relay Molecules

A

The molecules that relay a signal from a signal-receptor to the response

42
Q

2 main types of transduction pathways:

A

1) Membrane receptors
2) Internal receptors

43
Q

Membrane receptors vs internal receptors (transduction differences)

A

Membrane Receptors = Multi-step pathway that carries info from outside to inside the cell (usually contains a longer cascade)

Internal Receptors = Can carry out the transduction THEMSELVES (as they are already in the cell)
–> Usually less steps in the cascade

44
Q

Advantages of multi-step signal-transduction pathways

A

1) Amplification of signal = 1 signal can transmit info to multiple molecules at each step of the cascade

2) Regulation = Provide more opportunities for control and coordination (“more checkpoints”)

45
Q

Transduction mechanism =

A

= Conformational change: Signal causes switch between active and inactive forms of cellular proteins

46
Q

One main mechanism of transduction is… (most common)

A

phosphorylation

47
Q

The 2 potential substrates of protein kinases are…

A

1) The protein kinase itself (autophosphorylation)
2) Other proteins

48
Q

Phosphorylation Cascade

A

1) Signal binds to receptor
2) Activates relay molecule
3) Activates 1st protein kinase
4) Activates 2nd protein kinase
…
5) Final protein kinase activates a cell response

49
Q

Protein Phosphatases

A

THE INHIBITORS of phosphorylation

They DE-phosphorylate –> Remove phosphate groups

(Undo the work of protein kinases)

50
Q

Second Messengers

A

Small, non-protein, water soluble ions/molecules that cause relay proteins to react

(Second because “first messenger” is said to be the original signal)

51
Q

Major second messengers (4)

A

1) Ca2+
2) cAMP –> Cyclic AMP
2.1) IP3 –> Inositol Triphosphate
2.2) DAG –> Diacyl glycerol

52
Q

Cyclic AMP (cAMP)

A

A small molecule produced from ATP (second messenger of mainly G-Protein reception pathways)

53
Q

Adenylyl Cyclase

A

Enzyme that CREATES cAMP from ATP

(Closes ATP in on itself to create a cyclic molecule)

54
Q

Phosphodiesterase

A

Enzyme that breaks the third carbon bond of cAMP to get rid of the cyclic shape =

cAMP –> AMP

–> Deactivates cAMP

55
Q

cAMP in G-Protein Signal Pathway PROCESS

A

1) 1st messenger (signal) binds to G-Protein coupled receptor, activating it

2) Receptor binds to G-protein causing GTP to replace GDP, activating the protein

3) G-protein binds to Adenylyl Cyclase = triggers conversion of ATP –> cAMP

4) cAMP goes off and activates another protein = cascade begins

56
Q

Ca2+ Messenger

A

Functions in signaling through both G-protein and TKR reception

57
Q

Ca2+ cellular gradient

A

Inside cell [Ca2+] < Outside Cell [Ca2+]

–> cell wants less Ca2+ inside of it

58
Q

Processes that maintain the Ca2+ gradient

A

1) Cell is always pumping Ca2+ OUT of cell

2) Cell is always pumping Ca2+ INTO the ER

3) When [Ca2+] is suddenly greater inside cell: the cell will pump Ca2+ into MITOCHONDRIA

59
Q

The ER is a ________ for Ca2+

A

Repository for Ca2+ –>Stores it for when the cell needs it

60
Q

Ca2+ does not act alone, it uses assistance from…

A

1) IP3
2) DAG
3) Calmodulin

61
Q

Creation of IP3 and DAG

A

The signal activates the phospholipidase-C enzyme

–> Cleaves PIP2 (phospholipid) into IP3 and DAG

62
Q

Phospholipidase-C

A

Creates IP3 and DAG through cleaving PIP2

PIP2 –> IP3 + DAG

63
Q

DAG function

A

Remains in the membrane to activate a kinase

64
Q

IP3 function

A

Ligand for an ion-gate channel in the ER membrane

–> Causes the channel to open and begin releasing Ca2+ from the ER repositories

65
Q

Calmodulin function

A

Ca2+ binding protein –> Ca2+ binds to it and then this protein goes and binds to the next step of the cascade

66
Q

Ca2+ can activate the cascade in two ways:

A

1) Indirectly –> Using calmodulin
2) Directly –> Doing it itself

67
Q

Cellular Response

A

The “final destination” –> What the cell does due to transduction

68
Q

Two types of cell responses =

A

1) Cytoplasmic response

2) Nuclear response

69
Q

Cytoplasmic response

A

Regulates enzyme activity

–> Does not affect gene expression

70
Q

Nuclear response

A

Causes a change in gene expression

–> Activates/inactivates transcription factors

71
Q

Isolated pathway

A

Some signals only activate ONE specific cell/pathway

1 signal = 1 response

72
Q

Branched pathway

A

Some signals elicit MULTIPLE responses

1 signal = 2+ responses

73
Q

Crosstalk

A

Transduction pathways overlap: Interactions between pathways

–> DIFFERENT signals elicit the SAME response

74
Q

Glycogen Phosphorylase

A

Enzyme that breaks down glycogen

75
Q

Epinephrine induced breakdown of glycogen in liver pathway

A

Epinephrine –> Activates glycogen phosphorylase –> Breaks down glycogen = Energy production for body

76
Q

Epinephrine-glycogen pathway only occurs in LIVING CELLS: Why is this important?

A

Because it shows us that epinephrine does not directly activate glycogen phosphorylase (as when put into a test tube nothing happens) which signifies that there are other steps that occur in between to activate the pathway

BIO 202 (33 decks)

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