Exam 4 Part 1 Flashcards
interphase
includes G1, S, G2 phases. Cell increases in size, DNA is replicated, and centrosome duplicated
prophase
duplicated chromosomes (each consisting of two closely associated sister chromatids), condense. The mitotic spindle assembles between the two centrosomes, which have begun to move apart.
prometaphase
breakdown of the nuclear envelope. Chromosomes can now attach to spindle microtubules via their kinetochores and undergo active movement
metaphase
chromosomes are aligned at the equator of the spindle, midway between the spindle poles. The kinetochore microtubules on each sister chromatid attach to opposite poles of the spindle
anaphase
sister chromatids synchronously separate and are pulled slowly toward the spindle pole to whichthey are attached. The kinetochore microtubules get shorter, and the spindle poles also move apart, both contributing to chromosome segreation
telophase
two sets of chromosomes arrive at the spindle poles. A new nuclear envelope reassembles around each set, completing the formation of two nuclei and marking the end of mitosis. The division of the cytoplasm begins with the assembly of the contractile ring
cytokinesis
cytoplasm is divided in two by a contractile ring of actin and myosin filaments, which pinches the cell into two daughters, each with one nucleus
quiescent
just living and functioning - when a cell is in G0 phase
G1
growing in size, increasing materials
S phase
synthesis phase - when DNA is replicated
G2
more growth, checking the cell before entering mitosis
what the cell cycle must accomplish
events associated with each phase must be performed in the correct time and sequence
must respond to extracellular and intracellular cues
each phase must be completed before the next begins
three major checkpoints
G1 - is environment favorable? is DNA damage free? (committed step)
G2 - DNA replicated? Damage reparied? Enough materials?
M- Are all chromosomes attached to spindle? Enough materials present?
How to study cell cycle genes when knocking them out disrupts cycle?
Can make temp sensitive mutants or an induced knockout (found a kinase involved)
can also examine the proteins and ID cell cycle promoting factors (xenopus eggs)
2 proteins important for mitosis
Cyclin dependant kinases (Cdk)
Cylins