Test 3. Lecture 29 Flashcards
__________ are MICROTUBULE BASED PROJECTIONS of the plasma
membrane, responsible for
movement of a variety of eukaryotic
cells.
cilia and flagella
Some bacteria have______, but they
are protein filaments projecting
from the cell surface.
flagella`
_________beat in a coordinated back-andforth
motion, which either moves
the cell through fluid or moves fluid
over the surface of the cell.
__________ are longer, and have a
wavelike pattern of beating.
Cilia
flagella`
Structure of cilia and flagella is similar:
The ________ consists of microtubules in a “9 + 2” pattern: a central pair
surrounded by 9 outer doublets.
Each doublet is a complete A tubule fused to an incomplete B tubule.
______links the tubules, and 2 arms of __________ are attached to each A
tubule.
axonemeaxoneme
Nexin
dynein
The microtubule minus ends are anchored in a __________, similar in
structure to a centriole.
It has _________ of microtubules.
Basal bodies initiate growth of axonemal microtubules and anchor cilia and
flagella to the surface of the cell.
basal body
9 triplets of microtubles
Movement of cilia and flagella results from sliding of outer microtubule
doublets relative to one another, powered by motor activity of
__________________.
Dynein BASES BIND TO A TUBULES, while the HEAD GROUPS BIND TO B TUBULES
of adjacent doublets.
axonemal dyneins
Microtubules completely reorganize
during ___________
mitosis
Interphase microtubule array
disassembles and free tubulin
subunits are reassembled into
the ____________
mitotic spindle.
The centrosome is duplicated in
_________
interphase.
During __________, the centrosomes
migrate to form the two poles of
the mitotic spindle.
prophase
As the cell enters \_\_\_\_\_\_\_\_\_\_\_, the rate of microtubule disassembly increases, resulting in shrinkage of microtubules. But the number of microtubules emanating from the two centrosomes increases.
mitosis
What four types of microtubules make up the mitotic spindle?:
1. _____________ attach to the condensed chromosomes at
the centromeres, stabilizing them.
2. ____________ connect to chromosome ends via
chromokinesin.
3._____________ are not attached to chromosomes but are stabilized
by overlapping with each other in the center of the cell.
4. __________- extend outward from the centrosomes with the
plus ends anchored in the cell cortex.
- Kinetochore microtubules
- Chromosomal microtubules
3 Polar microtubules
4 Astral
________________________
- Kinetochore microtubules attach to the condensed chromosomes at
the centromeres, stabilizing them. - Chromosomal microtubules connect to chromosome ends via
chromokinesin. - Polar microtubules are not attached to chromosomes but are stabilized
by overlapping with each other in the center of the cell. - Astral microtubules extend outward from the centrosomes with the
plus ends anchored in the cell cortex.
After the centrosomes move to opposite sides of the cell, the duplicated
chromosomes attach to kinetochore and chromosomal microtubules,
and align on the metaphase plate.
Then the links between the sister chromatids are severed and anaphase
begins.
Chromosome movement occurs by what two movements?
- Anaphase A
2. Anaphase B
describe Anaphase A-
chromosomes move toward spindle poles along kinetochore microtubules, driven by kinesins that depolymerize and shorten the tubules.
This is coupled to disassembly and shortening of KINETOCHORE AND CHROMOSOMAL MICROTUBULES, mediated by KINESIN that act as microtubule-depolymerizing enzymes
describe Anaphase B-
spindle poles separate,
accompanied by elongation of polar
microtubules.
The overlapping polar microtubules slide
against one another to push the
spindle poles apart.
Plus-end-directed KINESINS cross-link
polar microtubules and move them
toward the plus end.
Spindle poles are pulled apart by the
astral microtubules.
Cytoplasmic DYNEIN anchored to the cell
cortex moves along astral
microtubules in the minus-end
direction.
Simultaneous depolymerization of astral
microtubules by middle motor
kinesins leads to separation of the
spindle poles.