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MBB 201 > Midterm 4 > Flashcards

Midterm 4 Flashcards

(71 cards)

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1
Q

cytosol

A

metabolic processes, protein synthesis, cytoskeleton

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2
Q

nucleus

A

contains main genome, DNA/RNA synthesis

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3
Q

ER

A

lipid and protein synthesis for distribution

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4
Q

golgi apparatus

A

modification, sorting, packaging of proteins/lipids for secretion or delivery to another organelle

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5
Q

lysosomes

A

intracellular degradation

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6
Q

endosomes

A

sorting of endocytosed material

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7
Q

mitochondria

A

ATP synthesis by oxidative phosphorylation

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7
Q

chloroplasts

A

ATP synthesis and carbon fixation by photosynthesis

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8
Q

peroxisomes

A

oxidation of toxic molecules

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9
Q

which organelles arose from invagination of the plasma membrane (6)

A
  • golgi
  • nuclear membrane
  • ER
  • peroxisomes
  • endosomes
  • lysosomes
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10
Q

which 2 organelles originated when aerobic prokaryotes were engulfed by pre-eukaryotic cells

A
  • mitochondria
  • chloroplasts
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11
Q

3 mechanisms by which proteins are transported into membrane-enclosed organelles

A
  • transport through nuclear pores
  • transport across membranes
  • transport by vesicles
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12
Q

signal sequences

A

necessary and sufficient to direct protein to a particular destination

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13
Q

nuclear pores (3)

A
  • span inner and outer membrane
  • composed of 30 unstructured proteins
  • fibril mesh
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14
Q

transport in/out of nucleus (3)

A
  • must contain nuclear localization signal which are recognized by nuclear import receptors
  • direct protein through pore by disrupting interactions btwn nuclear fibrils
  • nuclear import receptors require GTPase Ran
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15
Q

mRNA molec remains attached to the membrane independent to other ribosomes due to

A

signal recognition particles and receptors

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16
Q

membrane orientation of a protein given the start/stop signals in the AA acid

A

C, then N side with stop/start in membrane

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17
Q

clathrin-coated vesicle budding steps (6)

A
  1. vesicle begins as a clathrin-coated pit
  2. clathrin creates a network on the cytosolic surface of the membrane
  3. adaptins secure the clathrin to the vesicle and select cargo molecules by binding to cargo receptors
  4. cargo proteins have transport signals that can be recognized by the cargo receptors
  5. dynamin assembles a ring around the neck of the pit, pinching it off
  6. once complete, coat proteins are removed and the vesicle fuses with its target membrane
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18
Q

dock and fusion of vesicles on the correct recipient membrane (2)

A
  • possible due to Rab GTPases/proteins which are recognized and bound by tethering proteins
  • fusion occurs when v and t-snare wrap tightly around each other; energetically favourable
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19
Q

glycosylation (2)

A
  • covalent attachment of short branched oligosaccharides bunches
  • protect proteins from degradation, holds proteins in the ER, recognition by proteins for packaging or cell-to-cell interactions
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20
Q

Exit from the ER is controlled by (2)

A
  • signal sequence alerts receptors
  • retained by binding to chaperone proteins
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21
Q

unfolded protein response

A

chaperones/quality-control pros produced which inhibit pro synth

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22
Q

cisternae

A

flattened membrane-enclosed sacs

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23
Q

cis and trans

A

cis - adjacent to the ER, trans - plasma membrane; enter thru cis side exit thru trans

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24
constitutive secretion
supplies plasma membrane w/ lipids and proteins which are secreted - does not need signal seq; operates continually
25
regulated secretion
only in specialized cells - proteins sorted/packed in trans golgi network, in secretory vesicles near PM and wait for signal
26
phagocytosis (3)
- ingestion of large particles by specialized cells - food uptake and defense against infection - phagosome vesicles fuse with lysosomes for digestion
27
pinocytosis
- ingestion of fluid and molecs via small vesicles, all cells - receptor-mediated endocytosis pinocytosis allows selective uptake of macromolec using specific receptors
28
where does endocytosed material go? (3)
- recycling: returned to the PM - degradation: sent to lysosomes - transcytosis: move to another PM domain - early endosomes PM; late endosomes nucleus
29
lysosomes (2)
- acidic, hydrolytic enzymes to degrade macromolecs - membrane pros are highly glycosylated on the luminal side to protect from degrad - contains proton pump + transporters
30
autophagy (2)
- process by which a cell digests molecs/organelles that are damaged/obsolete - organelle enclosed by a double membrane, creating an autophagosome which fuses with a lysosome for destruction
31
signal transduction
Conversion of a signal or impulse from one form to another
32
steroid hormone
Hydrophobic molecules that can cross the plasma membrane
33
cells respond differently to the same signal
via receptors (survive, grow + divide, differentiate)
34
endocrine signalling
broadcast, hormones
35
paracrine signalling
local mediators to nearby cells
36
neuronal signalling
long distance targeted signalling to neurons - neurotransmitter
37
contact-dependent signalling
intimate/short name
38
fast conduction egs
kinase, GTP ase
39
slow conduction egs
making proteins
40
surface recceptors
large hydrophyllic
41
intracellular receptors
smaller, hydrophobic
42
phosphorylation activation/inactivation (2)
- involves protein kinases and protein phosphorylases - serine/theonine kinases or tyrosine kinases
43
GTP-binding proteins (2)
- active/inactive whether GTP or GDP bound - large, trimetric GTP-binding pros & monomeric GTP-ases
44
intracellular signalling pathways
amplify signals
45
cell surface signals (3)
1. ion-channel coupled receptors 2. g-protein coupled receptors 3. enzyme-coupled receptors
46
GPCR's activation (4)
- extracellular signal molec - changes conformation - G-protein results in the transmission of the signal and dec its affinity for GDP - GDP -> GTP - G proteins interact with target enzymes or ion channels
47
switching off G-proteins (2)
- alpha subunit contains a GTPase activity which hydrolyzes GTP -> GDP - alpha subunit reassembles the beta-y
48
process of producing cAMP-activated kinase
- generated from ATP, producing PPi - PKA inactivated by binding to a regulatory protein, binding cAMP to PKA relases the regulatory protein
49
CAMP slow vs fast
- PKA phosphorylates transcriptional regulators which can initiate transcription - PKA phosphorylate glycogen
50
inositol phospholipid pathway
- IP3 binds to and opens Ca2+ channels - DAG recruits a protein kinase C to the plasma membrane -> needs Ca to phosphorylate - GPCR
51
calmodulin
conformational changes of this Ca molec allow binding with helical peptides etc
52
GPCR signaling photoreceptors steps
1. light activtes GPCR rhodopsin 2. rhodopsin activates the G-protein transducin - alpha subunit of this activates cyclic GMP phosphodiesterase which reduces cGMP levels by converting it to GMP - affects cation channels, signal to brain - amplify in low light and adapt in high light (red Ca conc)
53
process by which RTKs propagate a signal (3)
1. signal molec from a dimer stimulate inactive RTKs 2. phosphorylated tyrosines 3. activation of downstream intracellular signalling pathways
54
RTK signal termination
protein phosphatases dephosphorylate the tyrosines
55
Ras in/activation
- activated by Ras-GEF (GDP for GTP) - inactivated by Ras-GAP (GTP -> GDP)
56
Ras & the MAP Kinase pathway (2)
- phosphorylation cascade (MAPK, MAPKK, MAPKKK etc) - pathway is involved in cell proliferation, survival, differentiation, cancer
57
PI 3-kinase-Akt pathway cell survival
Akt phosphorylates Bad and releases BCl2 which inhibits apoptosis
58
PI 3-kinase-Akt pathway cell growth
Akt activates Tor which enhances pro synth and inhibits pro degrad
59
contact dependent receptor eg
Delta notch
60
plant vs animal signaling (1s, 5d)
- similarity: transmembrane cell-surface receptors - differences: - diff serine/threonine kinases structural - no RTKs in plants - no steroid-hormone nuclear receptors - no cAMP - plants use very few GPCRs compared to animals
61
ethylene enables transcription of responsive genes in plants via
ethylene binds to receptor and pro kinase is inactivated, allowing transcription
62
intermediate filaments
- tensile strength, mechanical stress; strong and durable; internal reinforcement - euks - nucleus, plasma membrane at cell-cell junctions, nuclear lamina - no polarity
63
microtubules
- long, stiff, hollow tubes for transport of organelles - cell motility w/ cilia + flagella - polarity
64
actin filaments
- thinner flexible - polarity - microvilli, contraction, protrusions, pinch off during cell division
65
plectin
cross-links filaments into bundles and links them to microtubules/actin/desmosomes - allows to withstand mechanical stress
66
nuclear lamina
strengthen inner nuclear envelope and attachment sites
67
centrosome
microtubule organizing centre near animal cell nucleus - y-tubulin ring serves as the starting point for microtubule growth
68
dynamic instability
polymerization and depolymerization - grows and shrinks independent
69
dynamic instability stabilized by
binding to another molec or cell structure
70
drugs
affect de/polymerization of microtubules, which arrests cells during mitosis

MBB 201 (3 decks)

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