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54 Cards in this Set

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Microvilli contain _____ that are important for _____.

Microvilli contain ACTIN that are important for ABSORPTION.

Cilia and flagella contain ______ that enable _________.

Cilia and flagella contain MICROTUBULES that enable MOVEMENT.

Inside cilia and flagella is a microtubule-based cytoskeletoncalled the ______

axoneme (a pair of singlets)




the central microtubule unit

What is the arrangement of microtubulesin cilia and flagella?

9+2 arrangement




9 doublets lining the circle + 2 singlets in the middle

What is the motor that powers microtubule movement?

What is the MTOC of cilia and flagella?

basal body




a triplet organization of microtubules

Nexin

A MAP that joins adjacentouter doublets




forms radial projections from Atubule towards centralpair.

Axonemal dynein

induces controlled sliding of outer doublets




branches from A tubule of each doublet




each has an outer-arm dynein and an inner-arm dynein

What happens if nexin is removed?

nexin is removed by protease




microtubules slide past one another



Cytoplasmic dynein?

Intraflagellar Transport

movement of cargos up and down the cilia and flagella

What are the two motors that areimportant for intraflagellar Transport?

Kinesin-2: anterograde transport for


tip-directed movement




Cytoplasmic dynein: retrograde transport for base-directed movement

What is the biological function ofcilia?

sensory perception

Cilia mechanoreceptors

Cilium extend from epithelial cells lining the kidney tubules and monitors the flow offluids.

Cilia chemoreceptors

Cilium of olfactory neurons help detectodors.

Cilia photoreceptors

outer segment of the rods in the vertebrate retinaderived from cilium

Whathappens to kidney function if IFT is disrupted?

Disease like Polycystic Kidney Disease (PKD)




decreased ability to monitor flow








How do cilia and flagella lengthen?

Activation of dyne causes microtubules to slide past one another

What is the biological function of flagella

cellular movement

Stages of the Cell

MItosis (cell division)


G1 (cell grows)


S (replication of DNA)


G2 (cell prepares to divide)

Phases of mitosis

[[ Interphase ]]




Prophase


Prometaphase


Metaphase


Anaphase


Telophase




[[ Cytokinesis ]]

Interphase

chromosome duplication and cohesion




centrosome duplication





Prophase

breakdown of interphase MT




mitotic aster separation




chromosome condensation

Prometaphase

nuclear envelope breakdown




chromosomes brought to spindle equator

Metaphase

chromosomes align

Anaphase

APC/C activated: cohesins degrade




chromosomes move toward poles




spindle poles separate



Telophase

nuclear envelope reassembly




assembly of contractile ring

Cytokinesis

reformation of interphase microtubules




contractile ring forms cleavage furrow

3 classes of microtubules in the mitotic spindle

polar


astral


kinetochore



Polar MTs

from one spindle pole to another

Astral MTs

from spindle pole to cell cortex

Kinetochore MTs

from spindle poles to kinetochore

Kinesin-13

depolymerizes MTs at the minus end




pulls microtubules to the poles



Kinesin-5

walks toward plus ends




pushes microtubules toward the poles

What does XMAP-215 do to kinesin-13?

cancels it out!




XMAP215 stabilizes microtubules

How do Kinesin-13 levels change


during mitosis?

Kinesin-13 activity stays the same throughout mitosis and interphase

How do XMAP-215 levels change


during mitosis?

XMAP-215 activity is high during interphase


and low during mitosis




inhibited by phosphorylation during mitosis

Aremicrotubules more or less dynamic during mitosis?

More!




Microtubules become more dynamicbecause XMAP215 is inhibited.

centromere

region of DNA typically found near themiddle of a chromosome where two identical sister chromatidscome closest in contact.




involved in cell division as thepoint of mitotic spindle attachment

kinetochore

proteinstructure on chromosomes




CAPTURES and transports chromosomes




where the spindle fibers attachduring cell division to pull the chromosomes apart.

cohesins

protein complex that regulates the separation ofsister chromatids during cell division

Microtubules connect to inner or outer kinetochore?

Outer

What does Ran GTPase do?

regulates chromosomal attachment to the


microtubules

Which end of the microtubule attaches to the kinetochore?

plus end



Kinesin-13 activity involving chromosomes

depolymerizes MT plus end, too!




MT depolymerization causes force directed at spindle pole

Dynein activity involving chromosomes

dynein walks the chromosomes toward the minus ends (spindle poles)

Where isdynein enriched during prometaphase and metaphase?

at the spindle equator

Kinesin-4 activity involving chromosomes

walks along MTs OPPOSITE the spindle poles and toward the polar plus ends

What is chromosome congression?

Chromosomes move to central point between spindle poles

Kinesin-7 activity during chromosome


congression

walks chromosome toward plus end, away from spindle pole, as MT grows

What are the microtubules doing duringmetaphase?

treadmilling




Microtubule polymerization isoccurring at the kinetochore




Microtubule depolymerization isoccurring at the spindle pole

What moves the chromatids to their spindle poles during Anaphase?

Kinesin-13 activity depolymerizing the MTs at both ends

What is Kinesin-5 doing during Anaphase?

pushing spindle poles further apart

What is dynein doing during Anaphase?

Pulling on spindle poles via the astral


microtubules