cell biology

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sweetlu
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100744
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cell biology
Updated:
2011-12-08 13:13:31
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ross semster mini cell bio
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cel bio for mini 1
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  1. Ran
    a small GTPase that regulates cargo binding and release on exprtins and importans, based on whether it is in GTP or GDP from
  2. basic unit of DNA packaging
    nucleosome
  3. composed of intermediate filaments and provides mechanical support for the nuclear membrane
    nuclear lamina
  4. these 3 sequences are required to produce a eukaryotic chromosome that can be replicated and the seperated during mitosis
    telomere, replication origin and centromere
  5. targetting signal
    unique N terminal AA sequence required for a protein to be directed to a specific organele
  6. these recognize targetting signals on proteins, bind them and shuttle them to the nuclear pore complex for export or import
    importins and exportins
  7. How do ribosomal proteins that were shuttled into the nucleus get back out after ribosomal assembly
    during assembly the NLSs are 'hidden' inside the structure of the ribosome
  8. phospholipid composition
    glycerol backbone, 2 non polar FA hydrocarbon tails and a phosphate containing head group
  9. coline containing phospholipids
    sphingomyelin and phophotidylcholine
  10. molecules made in the smooth er
    • -all cholesterol
    • -most phospholipids (initally on the cytoplasmic half because enzymes ans substrates are in the cytoplasm)
    • -also involved heavily in detox reactions (50% with peroxisomes handling the other 50%)
  11. intergral proteins
    • -require an alpha helical domain of hydrophobic amino acids(at least 20 to pass all the way thru membrane)
    • -can pass through once or multiple times
    • CAN ONLY BE ROMOVED WITH THE USE OF A DETERGENT
  12. covalently tethered integral membrane proteins
    largely exposed and are COVALENTLY tehterd to either a phospholipid or glycolipid
  13. glycosylation
    • -occurs in the lumen of the er(N) and golgi(N and O)
    • -CHO is always found is outer leaflet of the plasma membrane (because enzymes that add the carb are inside the lumen of said organelles)
  14. lipid rafts
    -compostion
    -size
    • c-mostly sphingomyelin (choline containing) and cholesterol, also some phosphotidylcholine
    • s- thicker than the phospholipid bilayer
  15. lipofuscin
    bodies present in many undividing cells made up of residual bodies of lysosomal degredation
  16. intermediate filaments
    function
    structure
    pathology
    • f-mechanical strength
    • s- thought to be 8 tetramer filaments woven into a rope like structure
    • p- can be used to determine origin of tumor cells because different cell types have different IF
  17. IF types and cell types (6)
    • Keratins Epithelium
    • Vimentin Mesenchymal cells
    • Desmin Muscle
    • Gilial fibrillary Glial cells
    • Neurofilaments Neurons
    • Nuclear lamins surrounding internal NM NUCLEAR LAMINS ARE FOUND IN ALL CELLS TYPES
  18. centrosome
    • microtubule organzing center
    • anchors minus end of a microtubule
    • has a pair of centrioles perpendicular to eachother
  19. kinesin
    • MT motor that moves toward the + end of a MT (away from centrosome)
    • ATP driven
  20. Dynesin
    • MT motor that moves toward the - end of a MT (toward centrosome)
    • ATP driven
  21. microtubule
    function
    structure
    construction
    • f-determines postion of organelles and directs transport
    • s- 13 profilaments form a hollow MT
    • c- gamma tubulin provides nucleus and starts negative end, beta/alpha subunits attach(GTP) and detach(GDP) only at positive end
  22. cilia and flagella
    structure
    construction
    function
    • -made of MT in a (9+2) arrangement
    • -anchored to cell membrane by a basal body (which has same structure as centrioles- 9 sets of triplets)
    • f- movement- DYNEIN, using ATP, slides one doublet past another creating bend
  23. microfilaments
    • determine cell shape
    • made of actin, the most abundant protein inside cells
    • grows and shrinks at - and + ends
    • goverened by ARPs
  24. spectrin
    actin binding protein that forms supporting network for plasma membrane of RBC
  25. Taxol
    • defects mitotic spindle
    • prevents mitosis by stabalizing MT polymer and preventing dissasembly and thus cell division
    • binding site on beta tubulin
  26. cytochrome c
    • mobile in the intermembrane space of a mtch
    • its release will signal apoptosis
  27. mitochondrial dna
    • 37 genes
    • 2 rRNA, 22 tRNA and 13 protein
  28. cardiolipin
    • combo of 2 phopholipds that are combined in the mtch to strengthen the IMM to withstand the PMF
    • -an example of a PL not made in the ER
  29. 3 special structures of lysosomal membrane
    • -H+ pump- to keep acidic inner environmetn required to activate enzymes
    • -glycoprotein coat- protects inner membrane from acidic environment
    • -transport channels- eject broken down molecules
  30. Tay Sachs
    results from a absence of hexosaminidase A, which breaks down glycolipids in the lysosome
  31. peroxisomes
    -ez
    -function (3)
    -structure
    -abundance
    -O2 requirement
    • -contain catalase
    • -beta oxidize FA (as do mtch), syn bile, syn
    • PLASMOLAGENS USED IN MYELIN
    • -have a single membrane(not present in neurons)
    • -can adapt very fast to change in conditions (ie ingestion of EtOH)
    • -2nd major O2 user next to mtch
  32. checkpoints in cell division
    G1/S - (before replication) environment is assessed for favorable conditions, is DNA intact

    G2/M- (before division)DNA is checked for completion and accuracy, is DNA intact
  33. prometaphase signals what
    disappearance of nuclear envelope
  34. metaphase plate
    when the chromosomes are lined up in the center of the cell
  35. cohesins
    hold sister chromatids together and are degraded at anaphase allowing SC to be pulled apart
  36. condensin
    condenses DNA, only active during M phase
  37. anaphase A
    • - MT shorten to pull SC apart by motor proteins on the kinetocore
    • - SC acually roll down MT toward pole with the help of a motor protein that is part of the kinetochore
  38. anaphase B
    mitotic spindles pulled apart toward the cell wall via motors on the centrosome and on the MT anchoring the centrosome to the periphery
  39. when do sister chromatids divide
    metaphase/ anaphase transition
  40. kinetochore
    proteins that attach to the centromere of a chromosome and connect to (+) MT during cell division
  41. actin role in mitosis
    form contractile ring during cytokinesis
  42. what triggers the dissasembly of the nuclear envelope
    phosphorylation of lamins

    NE disassembly happens at prometaphase
  43. this normal cellular process continues during mitosis even when all others have stopped
    ATP production in the mitochondria
  44. key differences between necrosis and apoptosis (4)
    • apoptosis- dying cell phagocytosed
    • no inflammation or damage to adjacent cells
    • PM stays intact through whole process
    • cell shrinks
  45. caspases (4)
    • -ALWAYS activated during apoptosis
    • - cys proteases that degrade the insides of the cell
    • -always around inactive, waitng to be activated
    • -can cause cascade, activating other caspases
  46. BCL2 proteins (2)
    • -REGULATE APOPTOSIS in a pro- and anti- manner
    • - when deprived can cause OMM to become permeable, thus releasing cyt c, which will activate caspases
  47. 'eat me' signal
    • phosphotidylSERINE on external leaflet of membrane, put there by a non-specific scramblase
    • -ALWAYS HAPPENS WITH APOPTOSIS
  48. how does mtch get its lipids and proteins
    • -via non specific transport proteins (non targetting)
    • -NO SNARES on mitochondria so there can be NO VESICULAR transport from ER or golgi
    • -mtch channels are only wide enough for UNFOLDED AA to go thorugh
  49. Protein folding for organelles
    always folded prior to intake into organelle except in the case of mtch
  50. how does the nuclear membrane get its lipids
    diffusion
  51. cyt p450
    enzyme in SER involved in detox reactions
  52. ER sequesters what
    intracellular Ca
  53. what forms the cis golgi
    ER vesicles
  54. ER signalling sequence
    required to enter the secratory pathway and is at least 8 hydrophobic aa long
  55. SRP
    • -recognizes ER signal sequence and shuttles ribosomes that are translating proteins with ER signal sequence to the ER and aid connections and opening translocon channels
    • -translation stops while SRP is bound
  56. glutathione
    prevents disulfide bonding from occuring in the cytosol
  57. GPI anchor
    added in ER, can act as a sorting signal to direct membrane proteins to specific areas of the PM(lipid raft, calveoli)
  58. cotranslational transport
    membrane proteins that enter the secratory pathway, mtch membane proteins do not go this route
  59. hsp-70 and BIP
    • -binding proteins that aid protein folding by binding temporarily to hydrophobic regions
    • -hsp-70 in cytosol
    • -BIP in lumen of the ER, release is required to exit ER
    • -will give up if protein wont properly fold and protein will be ubiquitinated
  60. CFTR
    transmembrane Cl- channel that is defective in cystic fibrosis. It is not that the channel is non-functional, rather it slightly misfolds and is never released from BIP and is stuck in the ER then degraded
  61. what acts as the sorting staion
    trans golgi
  62. clathrin
    -involved in endocytosis from PM and movement from trans golgi to the endosome

    -a type of coat protein that will initiate budding, by covering outside and then must fall off to allow fusion

    -not part of constitutive p/w
  63. SNARES
    • -two types V(vesicle) and T(target)
    • -complimentary pairs, that excrude water when they bind and allow membranes to fuse
    • -targetting signals(and receptors) of vesicles
    • - no T-SNARES on mtch or mitochondria
  64. Rabs
    tethering proteins that aid connection of complimentary SNARE joining
  65. sialic acid
    • -groups on glycoproteins and glycolipids that give the outer leaftlet its negative charge
    • - added in the golgi
  66. where are glycolipids formed
    formed in the golgi
  67. glycocalyx
    thick layer of CHO that gives a 'cushion' to the PM
  68. M6P funciton and how is it attached and detached
    • mannose 6 phosphate- targetting signal for lysosome
    • -added to N linked sugar(which is added in the ER) on the acid hydrolase in the cis-golgi.
    • -in the trans glogi M6P binds a M6PR, which destines it for the lysosome
    • - acid hydrolase is disassociated from the M6PR in the low pH of the lysosome, M6PR is then recycled
  69. How are worn out organelles degrades
    by the lysosome in autophagosomes
  70. GPI-linked proteins cluster here
    • lipid rafts
    • (glycophphotidylinositol)
  71. adaptin
    binds cytosolic side of certain receptors as well as clarithrin, thus starting endocytosis
  72. LDL receptor
    internalization
    location
    • -internalized by receptor mediated endocytosis
    • - localized in the coated pits even before binding it ligand (LDL)
  73. ligand and EGF receptor(along with most other signalling receptors) fate after binding
    unlike LDLr, the ligand and EGFr(and most other signalling receptors) are targetted to the lysosome for degradation, this is one way to down regulate receptors, by not recycling them
  74. caveolae
    features
    function
    location
    • - NEVER FUSE WITH LYSOSOMES(think microbe entry, INDISTINGUISHABLE FROM LIPID RAFTS
    • -act as signalasomes
    • -small invaginations of PM, seen especially in endothelial cells, but absent in neurons
    • - maintained by caveolin
  75. ribosomes
    • made of rRNA(made in nucleolus)
    • large subunit- 3 rRNAs and proteins
    • small subunit- 1 rRNA and proteins (18s)
  76. MT
    • -start at gamma tubulin at - end of MT located in the MTOC
    • - grow and shrink on + end
    • - target of many anti cancer drugs(prevent mitotic spindle formation)
  77. actin
    • - grow at + end, shrink at - end
    • - shape PM
    • - form microvilli
    • - make lamellipodia
    • - contraction causes invagination during division
  78. chromosomes with rRNA knobs
    13, 14, 15, 21, 22
  79. kinetochore
    binding site for + ends of MT so sister chromatids can be pulled apart
  80. proteins translated in cytosol
    • - those destined for the cytosol, peroxisome and mitochondria
    • **mtch recieves NO vesicular transport**
  81. SNAPS
    - facilitate release of SNAREs for recycling
  82. KDEL
    ER retention signal
  83. chromosome numbers thru meiosis
    46(4n)-> meiosis 1-> 23(2n)-> meiosis 2-> 23(1n)

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