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chapter eleven Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

eukaryotic example of single-celled organisms communicating

A

Baker’s yeast - uses chemical signaling when producing sexually, then shape/fuse toward each other
- 2 sexes: a and alpha

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2
Q

prokaryotic example of single-celled organisms communicating

A

Bacterial cells - secrete signaling molecules, cell density monitored by quorum sensing, biofilms

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3
Q

biofilms

A

aggregation of bacterial cells attached to surface by molecules secreted by cells
- only after cells have reached certain density
- protects and provides nutrition

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4
Q

need for cell communication in eukaryotic multicellular organisms

A

embryonic development, immune response, adult stem pop. maintenance

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5
Q

external signals (primary messenger)

A
  • steroid molecules, proteins/glycoproteins, dipeptides, amino acids, gases
  • lead to response within cell
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6
Q

signal transduction pathway

A

sequence of changes in series of different molecules
1. signal reception
2. signal transduction
3. cellular response

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7
Q

examples of local distance signaling

A

paracrine, synaptic, autocrine

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8
Q

examples of long distance signaling

A

endocrine

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9
Q

paracrine signaling

A

signals/molecules only travel short distance to neighboring cells
- local regulators
- fast (just into ECF)
- handful of target cells
- growth factors

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10
Q

synaptic signaling

A

nerve cell releases neurotransmitter into synapse of target cell
- very targeted
- like subset of paracrine
- super fast (1 cell to 1 target across synaptic cleft)

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11
Q

autocrine signaling

A

cell secretes signal, but cell has receptors for own signal
- subset of paracrine

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12
Q

endocrine signaling

A

hormones secreted into fluids, only bounded by and affect some cells
- travels through blood
- slow-ish
- large number of possible target cells, but can only respond if it has receptors

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13
Q

what signaling molecules use receptors in the cytoplasm?

A

steroids and gases
- can diffuse through membrane
- hydrophobic/smal molecules

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14
Q

what signaling molecules use receptors on the plasma membrane?

A

proteins, dipeptides, amino acids
- most water-soluble molecules

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15
Q

3 stages of cell signaling

A
  1. reception - target cell receives signaling molecule, which binds to receptor protein
  2. transduction - protein receptor changed
  3. response - transducer signal triggers cellular response
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16
Q

signal reception

A

signaling molecule acts as ligand (specifically binds to another molecule)

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17
Q

examples of plasma membrane receptors

A
  1. G-protein coupled receptors
  2. receptor tyrosine kinases
  3. ligand-gated ion channels
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18
Q

G-protein coupled receptors (GPCR)

A
  • 7 transmembrane alpha helices, provide binding sites for signaling molecule and G protein
  • G protein binds to GDP when inactive and GTP when active
  • GTP + G-protein go to enzyme
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19
Q

receptor tyrosine kinases

A
  • ligand binding pushes them together to form dimer
  • dimer autophosphorylates, transferring P group from ATP to another protein
  • an activate 10+ different transduction pathways
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20
Q

ion-channel receptors (ligand-gated ion channels)

A

after the ligand binds, channel opens/closes to allow/block specific ions
- ions will only go through w/ gradient

21
Q

ex. of steroid hormones

A

aldosterone, testosterone, progesterone, estrogen

22
Q

ex. of signaling gases

A

NO, CO

23
Q

what happens to cytoplasm receptors upon binding

A

active form of receptor protein enters nucleus and turns on specific genes
- acts as transcription factor for mRNA
- both receptor and transducer

24
Q

what is being transducer?

A

proteins

25
Q

what does protein phosphorylation and dephosphorylation do?

A

transduction and shape change of proteins

26
Q

kinases

A

phosphorylation - transfer P from ATP to protein
- can act on each other to produce phosphorylation cascade

27
Q

phosphatases

A

dephosphorylation - remove phosphate groups from proteins, inactivating kinases
- turn off signal transduction pathway when initial signal no longer present
- make kinases available for reuse

28
Q

second messengers

A

small, nonprotein, water-soluble molecules or ions used in pathways

29
Q

2 main types of second messengers

A
  1. cyclic AMP
  2. calcium ions
30
Q

cAMP

A
  • made from ATP
  • catalyzed by adenylyl cyclase
  • binding of signal molecule to receptor (sometimes GPCR)
31
Q

calcium ions

A
  • cytosol concentrations of Ca2+ increase
  • transported out of cell and into ER by protein pumps
  • both GPCR/RTK
32
Q

where are calcium ion concentrations kept low?

A

in the cytosol

33
Q

inositol triphosphate

A
  • hydrolysis of PIP2
  • soluble
  • generated by phospholipase C
  • diffuses through cytosol and binds to IP3 gated calcium channel in ER membrane to open it
34
Q

diacylglycerol

A
  • hydrolysis of PIP2
  • insoluble
  • generated by phospholipase C
  • stays within PM and goes to other pathways
35
Q

what second messengers lead to Ca2+ release?

A

inositol triphosphate and diacylglyercol
- produced by cleavage of certain kind of phospholipid in membrane

36
Q

why are there different cellular responses to signaling molecules?

A

different collections of proteins

37
Q

gene regulation via activated transcription factor controlling

A
  • synthesis of mRNA, which will be translated into specific proteins
38
Q

gene regulation via regulating activity of proteins

A
  • outside nucleus
  • uses both second messengers and kinases
  • epinephrine -> breakdown of glycogen
39
Q

scaffolding protein

A

large relay protein to which several other relay proteins are attached

40
Q

what does termination of the signal depend on?

A

reversible ligand binding
- external concentration of ligands falls, fewer receptors bound, unbound receptors revert to inactive form

41
Q

apoptosis

A

type of controlled/programmed cell suicide

42
Q

how does apoptosis occur

A

DNA and organelles chopped, cell shrinks and becomes lobed, parts packaged in vesicles and digested by scavenger cells

43
Q

what is apoptosis essential for

A

embryonic development, metamorphosis, maintenance, nervous system, immune system

44
Q

external signals for life/death of cells

A

come from other cells

45
Q

internal sources for life/death signals

A

series of protein-protein interactions, nucleus (DNA) damage, ER (excessive protein misfolding)

46
Q

blebs

A

membrane-bound cell fragments in apoptosis
- cytoskeleton breaks up and forms bulges

47
Q

main proteases of apoptosis

A

caspases

48
Q

secondary messenger

A

internal, small, non-enzymatic, usually soluble

Biology (35 decks)

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