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63 Cards in this Set
- Front
- Back
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Microtubules are non-branching rigid HOLLOW tubes of proteins --- the walls are made up of ?
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Dimers of α-TUBULIN and β-TUBULIN
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One turn of a mircotubule is composed of how many Dimers?
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13 dimers
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PLUS (growing end) of a dimer/microtubule is the ? end
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β-TUBULIN
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MINUS (non-growing end) of a dimer/microtubule is the ? end
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α-TUBULIN
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? are Linear Structures produced by LONGitudinal contacts between dimers
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Protofilaments
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type of structure compose--
Cilia? Flagella? CENTRIOLES? Mitotic Spindle Elongating cell processes? |
Microtubules
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True or False
FREE DIMERS in the cytoplasm are in EQUILIBRIUM with dimers in the microtubules |
True
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What is DYNAMIC INSTABILITY?
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MICROTUBULES rapidly Assemble and Disassemble
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Microtubules grow from ? which is located on the ?
growth direction goes from Nucleus toward the Cell Periphery |
Microtubule Organizing Center (MTOC)
found on CENTROSOME |
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? molecules are assembled in the MTOC with the help of ?
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PROTOFILAMENT
GTP-TUBULIN (has GTP-ase activity) |
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? serves as the NUCLEATION SITE for Microtubule assembly
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γ-tubulin
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STABILIZES and REGULATE microtubule assembly and ANCHOR microtubules to specific organelles.
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Microtubule-Associated Proteins (MAPs)
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what are the 3 Molecular Motor Proteins (special MAPs) ?
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Kinesins
Cytoplasmic Dyneins Axonemal Dynein |
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What is the difference between CYTOPLASMIC and AXONEMAL DYNEIN?
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cytoplasmic Dynein ---> transport towards the MINUS end
axonemal Dynein ---> cause cilia/flagella movement |
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True or False
Hydrolysis of ATP is required for Molecular Motor Proteins (Kinesins and Dynein) to work. |
True
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Kartagener's Syndrome
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male / female INFERTILITY caused by DYSFUNCTIONAL MICROTUBULES affecting sperm motility and ciliary movement through the oviduct
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Vinblastine and Vincristine
--from PERIWINKLE plant cause the inhibition of ? useful for treating ? |
MICROTUBULIN POLYMERIZATION
treat cancer such as LEUKEMIA |
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What is TAXOL?
useful for treating ? |
INHIBIT DEPOLYMERIZATION OF MICROTUBULIN
--breast cancer |
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Contractile activity in cells is caused by ?
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ACTIN with MYOSIN
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Free cytoplasmic actin molecules
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G-Actin (globular)
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Polymerized Actin filaments are called?
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F-Actin (filamentous)
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True or false
Actin has GTP-ase activity. |
FALSE
--Microtubules = GTP-ase --Actin = ATP-ase |
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What are ACTIN-BINDING PROTEINS (ABP) ?
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REGULATE function and polymerization
induce BRANCHING prevent or enhance polymerization of actin filaments from G-ACTIN |
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Compare and Contrast
Plus and Minus end for Microtubules and Actin |
microtubules
PLUS --> growing β-tubulin MINUS --> no growth α-tubulin actin PLUS ---> fast growing MINUS ---> slow growing |
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What structure helps Anchor and Move MEMBRANE PROTEINS?
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Actin Filaments (Microfilaments)
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What forms the CORE OF MICROVILLI?
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Actin Filaments (Microfilaments)
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What helps maintain the shape of APICAL cell surface?
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Actin Filaments (Microfilaments)
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What helps in the LOCOMOTION OF CELLS such as lamellipodia and filopodia?
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Actin Filaments (Microfilaments)
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Which of the 3 structural proteins does not posses ENZYMATIC activity
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Intermediate Filaments
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Which of the 3 structural proteins does not have polarity?
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Intermediate filaments
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Intermediate Filament found in MESODERM DERIVED CELLS (CT, muscle, neuroglia)
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Vimentin
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A vimentin-like filament found in muscle
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Desmin
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True or False
Glial Fibrillary acidic protein (GFAP) is a type of vimentin |
True
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What type of intermediate filament would you find in NEURONS?
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Neurofilaments
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What type of structural protein is associated with the nuclear envelope?
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Lamins (Lamin A/B ---intermediate filament)
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What causes disassembly of Lamins in the nuclear envelope?
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PHOSPHORYLATION by protein kinases
dephosphorylation causes REASSEMBLE |
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Desmosomes and Hemidesmosomes are associated with what type of structural protein?
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Intermediate Filaments
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Cell-to-Cell attachment involve what intermediate filament-associated proteins?
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desmoPLAKIN
PLAKOglobins |
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What is the CENTRIOLE structure composed of?
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9 MICROTUBULE triplets
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? is the region of the cell containing the centrioles and surrounding material also called the MTOC
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Centrosome
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MTOC depends on the presence of ?
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centrioles
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? of microtubule remains ATTACHED to MTOC and the ? grows AWAY
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MINUS END ---attached
PLUS END ---grows away |
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What are the 2 mechanisms that PROCENTRIOLES are generated by?
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ACENTRIOLAR -- no contact with existing centrioles (95%)
CENTRIOLAR -- duplication of existing centriole (5%) |
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PROCENTRIOLES migrate to cell surface to become ?
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Basal Bodies
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? serves as organizing centers for the assembly of microtubules of the cilium or flagellum.
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Basal Bodies
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the core structure of a cilium is called a ?
it is composed of ? |
AXONEME
(9+2) 9 Doublets -- 2 Central microtubules |
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when does CENTRIOLE REPLICATION and MITOTIC SPINDLE FORMATION occur in the cell cycle?
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DNA synthesis (S phase) of cell division
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when a centriole replicates ---
a small ? appears at the side of each centriole and enlarges to form a right angle appendage to the adult |
PROCENTRIOLE
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After centrioles have replicated what forms?
what does it produce that defines the poles? |
MITOTIC SPINDLE FORMATION
Astral Microtubule |
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DNA and associated proteins are called...
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Chromatin
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site of ribosomal RNA (rRNA) synthesis
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Nucleolus
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contents, other than chromatin and nucleolus, enclosed by the nuclear envelope
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Nucleoplasm
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condensed CHROMATIN, predominates in metabolically inactive cells (ex: lymphocytes)
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HETEROchromatin
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discrete bodies of irregular size and shape throughout nucleus
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karyosomes
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condensed DNA near centromeres,
--genes that are transcriptionally SILENT are recruited here |
pericentromeric heterochromatin
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what are the 3 locations of heterochromatin?
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marginal chromatin
karyosomes pericentromeric heterochromatin |
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? is lightly staining chromatin due to active DNA TRANSCRIPTION
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euchromatin
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chromatin prominent in metabolically active cells (ex: neurons, liver)
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Euchromatin
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What on the euchromatin are responsible for the BASOPHILIA?
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phosphate groups
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proteins associated with all chromatin
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histones
non-histone proteins |
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Describe the basic structure for a Intermediate Filament
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intermediate filament protein has::
-Variable Rod-Shaped Domain -Conserved Globular Domain pair of helical MONOMERS >> coiled-coil DIMERS >> antiparallel fashion >> staggered TETRAMERS >> link to form FILAMENTS |
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What structural protein has the greatest tensile strength?
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Intermediate Filaments
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Intermediate Filament found in cells of EPITHELIAL ORIGIN
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Keratins
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