exam 3- lecture 11 Flashcards

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1
Q

what do all cells do from the environment

A

process information

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2
Q

what does a signal transduction pathway do

A

sequence of molecular events and chemical reactions that lead to a cells response to a signal

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3
Q

steps in cellular signalling

A
  1. the signal binds to a receptor, activates
  2. the signal is transmitted to the interior of the cell by a signal transduction pathway
  3. the cell responds by activating an enzyme or turning on the transcription of a gene
  4. the response is terminated so that new signals can be received
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4
Q

at low cell density

A

the concentration of the signaling peptide is too low to stimulate DNA uptake by bacteria

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5
Q

at high cell density

A

the concentration of the signaling peptide is high enough to stimulate the DNA- uptake response

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6
Q

types of cell signaling

A
  1. endocrine
  2. paracrine
  3. autocrine
  4. contact-dependant
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7
Q

endocrine signals do

A

travel to distant cells, by the circulatory system

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8
Q

paracrine signals affect

A

nearby cells, in the nervous system

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9
Q

autocrine signals affect

A

the cells made by them

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10
Q

contact dependant signals have

A

no diffusion and cells touch

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11
Q

what are the two types of cell signaling receptors

A

membrane
intracellular

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12
Q

membrane receptors are

A

in the plasma membrane and bind polar lignads
ex insulin (protein)

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13
Q

intracellular, or cytoplasmic, receptors are

A

in the cytoplasm and bind nonpolar ligands that can diffuse across the pm
ex estrogen, a steroid lipid

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14
Q

binding the ligand causes the receptor protein to

A

change chape or conform

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15
Q

what can also bind to receptor proteins

A

inhibitors or antagonists

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16
Q

how do signal receptors initiate a cellular response

A

G protein-coupled receptors
Heterotrimeric G proteins

17
Q

G protein-coupled receptors

A

bind heterotrimeric G proteins
ligand binding to GPCRs activates G proteins

18
Q

Heterotrimeric G proteins

A

Membrane-associated proteins with three subunits
Bind GDP (inactive) or GTP (active)

19
Q

GTP bound alpha subunit separates from the other subunits and encounters an

A

effector protein

20
Q

what does the enzyme adenylyl cyclase do

A

catalyzes the formation of cAMP from ATP

21
Q

how is the response to a signal transduced through the cell

A

first messenger
second messenger

22
Q

how does the first messenger go through the cell

A

ligand signal

23
Q

how does the second messenger go through the cell

A

small water soluble, non-protein molecule
relays the initial signal to target molecules inside the cell
amplify the signal

24
Q

1 molecule of adrenaline makes

A

1000s of glucose molecules

25
Q

the first step of termination of G protein signal

A

the signal molecule detaches from receptor, inactivating the receptor so it can no longer bind to the g protein

26
Q

the second step of termination

A

an activated G protein deactivates itself by converting GTP to GDP

27
Q

the third step of termination

A

enzymes specifically degrade cAMP which stops the phosphorylation and activation of target proteins by PKA

28
Q

the fourth step of termination

A

phosphatases remove phosphate groups from proteins, causing them to be inactive

29
Q

what do the protein kinase receptors catalyze

A

catalyze the phosphorylation of themselves and or other proteins

30
Q

protein kinase receptors catalyze

A

the phosphorylation of themselves and other proteins

31
Q

the insulin receptor

A

phosphorylates itself and other insulin response substrates

32
Q

some cancer cells have too many protein kinase receptors which results in

A

overactivation of the MAP kinase signaling pathway and increased cell division
Herceptin is used as a breast cancer treatment

33
Q

ion channel receptors are

A

channel proteins that allow ions to enter or leave a cell