ch. 9 cell communication Flashcards

1
Q

what two things are required for communication between cells?

A

a ligand and a receptor

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2
Q

what is a ligand?

A

a signaling molecule

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3
Q

what is a receptor?

A

a protein to which the ligand binds

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4
Q

where are receptors located?

A

may be on the plasma membrane or within the cell

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5
Q

what are the four basic mechanisms for cellular communication?

A
  1. direct contact
  2. paracrine signaling
  3. endocrine signaling
  4. synaptic signaling
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6
Q

what is direct contact?

A

when ligand molecules on the surface of one cell are recognized by receptor molecules on an adjacent cell

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7
Q

what is paracrine signaling?

A

when ligands released from a secretory cell bind to receptors on adjacent cells.

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8
Q

what is endocrine signaling?

A

when special ligands called hormones are released from secretory cells and bind to receptors on or within cells throughout the body

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9
Q

what is synaptic signaling?

A

when nerve cells release the signal ligands (neurotransmitters) which binds to receptors on nearby nerve or muscle cells.

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10
Q

what happens when a ligand binds to a receptor?

A

the cell “responds” chemically

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11
Q

what is signal transduction?

A

the series of chemical reactions that occur following the binding of a ligand to a receptor

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12
Q

what can different cell types respond differently to?

A

the same signaling ligand

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13
Q

what does signal transduction often involve?

A

activating or inactivating proteins

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14
Q

what is kinase?

A

an enzyme that adds a phosphate to a protein, thus activating it

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15
Q

what is phosphatase?

A

an enzyme that removes a phosphate from a protein, thus deactivating it

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16
Q

what happens during protein phosphorylation?

A

a phosphate group (PO4-3 ) is added by a kinase to residues of the amino acids serine, threonine, and tyrosine. This can activate the protein.

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17
Q

what are the two receptor locations?

A

cell surface and inside the cell

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18
Q

what is an intracellular receptor?

A

a receptor located inside the cell

19
Q

what are the three classes of membrane receptors?

A
  1. channel linked/gated receptors
  2. enzymatic receptors
  3. G protein-coupled receptors
20
Q

what are Channel linked or gated receptors?

A

class of membrane receptor where an ion channel opens in response to ligand binding

21
Q

when do receptors fall into the enzymatic class?

A

when the receptor is an enzyme that is activated by ligand binding

22
Q

what happens with G protein-coupled receptors?

A

a G-protein (protein bound to GTP) assists in transmitting the signal

23
Q

what is receptor tyrosine kinase?

A

an enzyme receptor

24
Q

what happens to the membrane bound receptor when signal ligand binds?

A

it is dimerized and autophosphorylated- activated receptor then adds a phosphate to tyrosine on a response protein

25
what is an example of receptor tyrosine kinase signaling?
epidermal growth factor receptor
26
what is a kinase cascade?
a series of protein kinases that phosphorylate each other in succession, amplifing the signal
27
what is the purpose of a kinase cascade?
So, a few signal ligand molecules can elicit a large cell response
28
what is a G protein?
protein bound to GTP
29
what is a G protein coupled receptor?
receptors bound to G proteins
30
_________ is a switch turned on by the ________.
G protein; G protein coupled receptor
31
when a signal ligand binds receptor, what does G-protein activate?
an effector protein
32
what can activate effector proteins?
G-protein coupled receptors
33
what does the effector protein produce once activated?
a second messenger
34
what does a second messenger do?
generates the cellular response
35
what is an example of a common effector protein?
adenylyl cyclase
36
what does adenylyl cyclase do?
converts ATP to cAMP, which then acts as a second messenger
37
what is the function of a cyclic AMP?
serves as a second messenger to activate or inactivate proteins
38
are steroid hormones polar or non-polar?
non-polar/lipid soluble
39
why are steroid hormones nonpolar?
so that they can cross the plasma membrane to a steroid receptor
40
what is the function of steroid hormones?
Usually regulate gene expression: an inhibitor blocks the steroid receptor from binding to DNA until the hormone is present.
41
what are the three functional domains of a steroid receptor?
1. Hormone-binding domain 2. DNA binding domain 3. Domain that interacts with coactivators to affect gene expression (activating or deactivating transcription)
42
what are autoinducers?
small molecules produced by bacteria that regulate gene expression
43
what type of receptor are steroid hormones?
intracellular