Chapter 19.2 Flashcards
What parts of cell cycle make up interphase
G1, S, G2
what happens in G1
cell increases in size, nucleus moves to middle of cell, organelles divide
what is G0
when arrested cells stay in G1 (neurons are example of this)
what happens in S phase
DNA is replicated
what happens in G2 phase
structures necessary for mitosis are produced
steps of mitosis
prophase, prometaphse, metaphase, anaphase, telophase
parts of prophase
chromosomes condense
cytoskeleton begins to disassemble
centomere
constricted region of each chromatid where the sisters are attached
centrosome
microtubule organizing center
hallmarks of prometaphase
nuclear envelop disappears
nucleolus disappears
kinetochores develop
centrosomes move apart and spindle fibers appear
Kinetochore MT
attach to chromosomes at kinetochores
kinetochore
proteins associated with the centromere that acts as a handle for the spindle fibers
Polar MT
interact with spindles from opposite pole
Astral MT
form the asters at each pole which anchor centrosomes in place
Features of metaphase
chromosomes are maximally condensed
chromatids line up on metaphase plate
cell seems to pause
specifics of anaphase
sister chromatids separate at centromeres
move toward poles
anaphase A movement
chromosomes pulled apart (toward centrosomes)
anaphase B movement
poles themselves move apart
steps of telophase
daughter chromosomes reach opposite poles chromosomes uncoil (elongate) nucleoli develop spindle disassembles nuclear envelopes form cell undergoes cytokinesis
Roles of mitotic motors
move chromosomes
movement of spindle poles
exert a pull on spindle poles
how do mitotic motors work
use energy from ATP to change shape
basic steps of cytokinesis in animal cells
formation of cleavage furrows in early anaphase
belt-like bundle of actin microfilaments make a contractile ring
ring closes separating the cells
what makes up the contractile ring during cytokinesis
actin microfilaments
basic steps of cytokinesis in plant cells
microtubules organized into phragmoplast
directs cell wall material to form cell plate
made of vesicles from the golgi
formation of cell plate
what is phragmosome
zone of cytoplasm between nuclei
where cell plate is formed
what is phragmoplast
barrel shaped structure that directs cell wall material to form cell plate
restriction point
checkpoint in late G1 that checks for specific nutrients and growth factor
G2-M transition
commitment to mitosis once passed
checks for cell size and DNA replication
metaphase-anaphase transition
commitment to separate chromosomes
checks for chromosome attachment to spindle
maturation promoting factor (MPF)
induces meiotic cell division
aka mitotic CdK-cyclin complex
what type of cells are karyotypes taken from
metaphase arrested
what drug is used to make karyotypes
colchine
interferes with metaphse-anaphase transition by hindering MT
function of mitotic cyclin
regulates progression through euk cell cycle
increased levels lead to activation of MPF and mitosis
which is stable and which cycles
stable is CdK
cyclin cycles
steps of activation of CdK-cyclin complex
- mitotic CdK and cyclin form an incactive complex
- inhibiting kinase adds 2 Phosphates which block active site
- activating kinase adds third phosphate
- phosphatase removes the 2 inhibiting Pi
- CdK-cyclin becomes active
- stimulates phosphatase to produce more active complexes
why must cyclin be degraded after mitosis
otherwise it would induce the cell to go through mitosis before it is ready
what happens to cyclin levels during interphase
increases at a steady rate
