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Glossary of Life 210 Final

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The difference between Kinesins and Dyneins is...
Kinesins walk toward the + end and dyneins walk toward the - end of microtubules
Kinesins and Dyneins
often move in opposite directions of each other
Myosins and Kinesins
Both bind cargo directly with their tails, while dyneins often bind through adapters.
Myosin I and Myosin II
Both bind actin filaments
"Rigor" and "rigor-like" refers to
the most tightly actin filament or microtubule bound states of motor proteins
ATP binding and hydrolysis and ADP release on motor proteins
causes swiveling and swinging of the head groups
myosins
form contractile rings with actin in dividing cells AND have heads which contact actin filaments
The mechanism of motor protein movement along filaments
involves using the energy of ATP hydrolysis by the head to drive conformational changes.
The mechanism of myosin motor protein movement along filaments
includes a "rigor" state where the head is bond tightly to the filament, but not by ATP or ADP
Molecular motor proteins
function to pull cargo or other filaments along actin filaments and microtubules
Dyneins and kinesins
Both bind microtubules
The type of cytoskeletal filament that does not have associated motor proteins is
intermediate filaments
Which is more processive, Myosins or dyneins?
Dyneins
Lamellipodia
are two-dimensional sheet-like protrusions
Filopodia
contain long, thin bundles of parallel actin filaments similar to microvilli
cellular crawling
can be broken down into protrusion, attachment, and traction/contraction
Non diffusible chemical cues
trigger cell adhesion and actin polymerization
During crawling actin filaments
treadmill through the actino of Arp2/3 complexes, ADF/cofilin, and profilin.
As part of the process of cellular movement and crawling (first step)
the plasma membrane is first extended forward in a process called protrusion.
Actin filament structures
form a loose two dimensional mesh-like sheet in lamellipodia
During cell crawling
actin filaments treadmill, pushing outward on the forward edge of the plasma membrane
Pseudopodia
are three dimensional projections
During treadmilling, the protein responsible for severing actin filaments is
ADF/cofilin
Nerve cell axons
contain neurofilaments that determine the axon diameter
M phase
is when chromosome segregation and cell division occurs
Cell cycle checkpoints
often signal that a key cell process like DNA synthesis is incomplete or incorrect
Interphase is
all the steps in the cell cycle not included in M phase
Cell cycle checkpoints can
arrest cell cycle progression
Checkpoints in the cell cycle are important
to ensure that every step is correctly completed
In the most basic sense the cell cycle consists of all of the following except
cyclic changes in the concentration of Cdks
A structure that breaks into fragments prior to cell division is
the nuclear membrane
The cytoskeleton of an animal cell changes between G1 and prophase in that
the phosphorylation state of centrosomal proteins changes
The Gap phases, G1 and G2
are when cells grow and duplicate cell components
A serine to alanine mutation in the phophorylation site of a lamin protein will
stabilize the nuclear lamina and thereby prevent its disassembly
Cyclin-dependent kinases are regulated
positively through cyclin binding, CAK phosphorylation and removal of the phosphorylation put on by a CKI
The regulation of Cdks does not occur through
cyclic changes in the expression levels of the Cdk proteins
The cell cycle has four stages:
G1, S, G2, and M (mitosis and cytokinesis)
DNA is replicated during
S phase
The core cell cycle controllers
function as biochemical ON/OFF switches
Xenopus eggs have been useful for the study of cell cycle control
due to the extremely large cell size
An event preceding the reformation of the nuclear envelope during M phase is
formation of the contractile ring
S-Cdk
iniiates DNA replication and blocks rereplication
Cdks are
the core controllers of the cell cycle
Transcriptional activator protein E2F
is activated through Rb phosphorylation
Rb protein functions in...
G1 arrest
The first cyclin-Cdk complex that responds to growth factor signals is
G1-Cdk
Escape from G1 phase
is kept in check by p27 CKI and Hct1-APC in the absence of mitogens
The M phase checkpoint involving Mad2
sends a negative signal until all the centromeres are attached to mitotic spindles
Exit from M phase
occurs through M-Cdk activation of the M-cyclin ubiquitin ligase complex.
Cells in the G0 state
can remain in that state for a lifetime
The cell cycle checkpoint control that results in the phosphorylation and activation of p53 is
G1 phase DNA damage
The concentration of mitotic cyclin
falls during M phase due to ubiquitination
Four Cdk regulatory mechanisms do not include
ubiquitin ligase-mediated turnover of Cdk proteins

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