Organelles II Flashcards
______ are the most dynamic cytoskeleton.
Microtubules
_____ is the protein that makes up microfilaments
Actin
Actin binds to ____ to polymerized and form microfilaments. Unpolymerized actin monomer is soluble and called ____. Polymerized actin is called ___ and forms microfilaments. _____ ____ proteins are responsible for actin changes.
ATP
G actin
F actin
Actin associated
Microfilaments have ___. It is easier for G-actin (actin monomers) to be added to the ____ end and removed from the ____ end.
Polarity
Positive
Negative
Microfilaments are usually on the _____ of the cell and interacts with the plasma membrane. They participate in the formation of specialized epithelial cell appendages, such as ____ and ___.
Periphery
Microvilli
Filopodia
_____ is a meshwork formed from microfilaments found in specialized cells.
Lamellipodium
Microfilaments form a ____ in a dividing cell.
Cleavage furrow
Numerous actin associated proteins influence microfilament organization and function. For example ____ cross links microfilaments into parallel bundles. _____ cross links filaments to allow for 3D network formation.
Fimbrin
Filamin
Microfilament-membrane linkages play a key role in cell function. _____ proteins and ____ link microfilaments to the plasma membrane. _____ links microfilaments with the plasma membranes in muscle cells
ERM
Vinculin
Dystophrin
Linking/anchoring proteins are usually _____ proteins.
Transmembrane
_____ family GTPases are master regulators of the actin cytoskeleton. They modulate the activity of numerous _____ ____ proteins, including a number of protein kinases.
Rho
Actin associated
_____ ____ polymerize to form bipolar fibers, there long tails wrap around each other in an antiparallel orientation. This allows them to pull microfilaments past each other, used in ____ contraction. Unconventional myosin’s bind to different ____ in the cytoplasm and participate in vesicular trafficking.
Type II myosins
Muscle
Cargo
What are the main functions of microfilaments?
- Support plasma membrane
- strengthens cell to cell adhesion
- support microvilli
- physically interconnects the plasma membrane, cytoplasm, extra cellular matrix, and nucleus
- Interacts with myosin
- Drives cytokinesis during cell division
_____ has GTPase activity and polymerizes into microtubules. ____ and ____ tubulin bind to form dimers which then polymerize into microtubules. The beta end forms the _____ side of the tubule and the alpha end forms the ____ side.
Tubulin
Alpha
Beta
Positive
Negative
_____ _____ is the tendency for microtubules to polymerize and depolymerize
Dynamic instability
It is easier for tubulin to add to the ____ end and be removed from the _____ end.
Positive
Negative
A _____ protects and anchors the microtubules negative end, leaving the positive end free in the cytoplasm. This is the dominant factor in the _____ of microtubules.
Centrosome
Organization
When _____ binds to the heterodimer, it will be added to the microtubule. When _____ binds to the heterodimer, it will be released.
GTP
GDP
Centrosomes are composed of _____, a short cylinder composed of 9 microtubules. The _______ _____ surrounds the centrioles, contains TURCs which nucleate microtubule polymerization.
Centrioles
Pericentriolar material (PCM)
____ ____ is a form of centrosome during cell replication.
Spindle poles
A ____ ____ is a specialized centriole that migrate to the apical region of a cell and form cilia and flagellae
Basal bodies
Cilia and flagellae are motile and supported by a bundle of microtubules called an _____, that exert a bending force on their neighbors via ____ motor bridges which powers their motion.
Axoneme
Dynein
Axoneme are a cylinder with ____ doublets surrounding ____ central microtubules
9
2
MT organization is regulated by structural proteins including ____ and ____. _____ interconnects microtubules with other cytoskeletal elements
MAPs
Tau
Plectin
Two categories of microtubule motor proteins are ____ and ___, they move cargo to the - and + end respectively
Dyneins
Kinesins
Phosphorylation promotes _____ of intermediate filaments. Dephosphorylation promotes _____.
Depolymerization
Polymerization
In intermediate filaments, two monomers form a ____ ___ dimer, followed by tetramer and octamers
Coiled coil
Unlike MF and MT, IF do not have _____.
Polarity
______ is a common site of phosphorylation in intermediate filaments.
Serine
There are categories of IF including ____ , ____, ____ ,_____.
Nuclear lamins
Vimentin-like
Keratins
Neurons and ganglia
How are IF organized in the cell?
In the cytoplasm, around the nucleus, attach to plasma membrane, cell adhesion junctions, and the extra cellular membrane space
______ are critical in epithelial cells to resist mechanical forces through the formation of cell to cell and cell to extra cellular matrix adhesions. _____ are cell to cell IF adhesions. _____ are cell to ECM IF adhesions.
Intermediate filaments
Desmosomes
Hemidesmosomes
What are the major functions of intermediate filaments?
- Strengthen the cytoplasm and nucleus
- Strengthen mechanical integrity of epithelial cells
- Protect from the environment
- Provide warmth and defense
____ ____ ____ is the migration of single cells. _____ ____ ___ is the migration of clusters or sheets of cells.
Single cell motility
Collective cell motility
Two major type of single cell motility are _______ and _____ motility.
Mesenchymal
Ameboid
Compare and contrast mesenchymal and ameoboid motility:
G proteins, ____, promote actin polymerization at the front of the cell, pushing the plasma membrane forward, driving mesenchymal motility. ______ interacts with actin at the rear of the cell to pull the back end forward.
Rac
Myosin II
____ ____ provide for necessary traction points for mesenchymal motility. They are bundles of microfilaments linked to the extra cellular matrix
Focal adhesions
Focal adhesions are associated with signaling functions via ____ ____ ____ and ____ which are both non-receptor tyrosine kinases.
Focal adhesion kinase (FAK)
Src
Signaling functions of focal adhesions picture:
Mutations in dystrophin, a linking protein between actin filaments and the plasma membrane weakens the muscle membrane and can lead to cell death. This disease is called ____ ____ ___.
Duchenne muscular dystrophy
______ is involved in formation of neurofibrillary tangles which are toxic to neurons causing diseases such as Alzheimer’s.
Tau protein
_____ is a clinically useful cancer chemotherapeutic agent. It binds to MT in dividing cells and stabilizes them, preventing chromosome separation, causing cell death. Targets cancer cells
Taxol (Paclitaxel)
____ _____ ____ is a genetic blistering disease caused by mutations in keratins.
Epidermolysis bullosa simlex (EBS)
_______ is a disease of accelerated aging caused by perturbations in lamin.
Progeria
_____ _____ _____ involves a loss of epithelial characteristics and a gain of mesenchymal characteristics, therefore interconnected cells break loose and become mobile. This is normal in embryonic development. However, this process is used in cancer cells to gain motility and become _____.
Epithelial mesenchymal transition (EMT).
Metastatic
