mitosis & meiosis Flashcards
What important events occur during interphase to set the cell up for successful M phase?
-advancement through check points
-duplication of centrosome
-DNA replication
-chromosomes begin being loosely packed
What is the G0 phase for?
it is a mechanism by which specialized tissues control where and when its cells divide. basically for cells that do not want to replicate
which checkpoint is critical for inhibiting cancer?
G2
biochemical circuits that can detect either external or internal problems and in response to these, will inhibit the cell cycle
checkpoints
the core components of the cell cycle clock and represent the cellular signals used to transition from one phase to the next
cyclins and cyclin dependent kinases
when does centrosome duplication begin and end?
begins in S phase but ends in G2
what are the 5 stages of mitosis?
prophase
prometaphase
metaphase
anaphase
telophase
what two proteins regulate the condensation of chromosomes?
-cohesin ties the sister chromatids together
-condesin packs the DNA coils tightly
at what point do the chromosomes condense into observable forms in the microscope?
prophase
what happens at prophase?
-chromosomes condense
-outside the nucleus, mitotic spindle assembles between the two centrosomes
what happens at prometaphase?
-the nuclear envelope breaks down
-chromosomes attach to spindle microtubules via their kinetochores and undergo active movement
what could cause a cell to arrest at prometaphase?
if the sister chromatids are not contacted by spindle fibers of BOTH pairs of centrosomes
what happens at metaphase?
-the chromosomes are aligned at the equator of the spindle, midway between the spindle poles
-the kinetochore microtubules attach sister chromatids to opposite poles of the spindle
what are the 3 classes of microtubules within the fully formed mitotic spindle and what are their functions?
-astral: anchor
-kinetochore: attach to chromatids and pull
-overlap: attach to each other and push
what happens during anaphase?
-sister chromatids separate to form two daughter chromosomes and each is pulled slowly toward the spindle pole it face
-kinetochore microtubules get shorter and spindle poles move apart
what triggers the metaphase to anaphase transition?
anaphase promoting complex
when are chromatids considered daughter chromosomes?
once they are separated
coordinated disassembly of kinetochore microtubules and action of ________________allow progression of chromosomes toward spindle poles?
Dyneins
Kin1 acts as a ?
microtubule disassemblase
a component of kinetochores that is +end directed motor critical for initial metaphase chromosomal alignment
Centromere protein E (CENP-E)
+end directed motors associated with the chromosomal arms and drive the arms away from the pole, producing the chromosomal ejection force
chromokinesins
what happens at telophase?
-the two sets of daughter chromosomes arrive at the poles of the spindle and decondense
-a new nuclear envelope assembles around each set, completing the formation of two nuclei and marking the end of mitosis
the division of cytoplasm begins with the assembly of what?
the contractile ring
what happens during cytokinesis?
the cytoplasm is divided in two by a contractile ring of actin and myosin filaments, which pinches the cell in two to create two daughters with one nucleus
