Bio 1A03 Test 3
Binary Fission steps
-Initiated when proteins attach DNA to plasma membrane
-Begins along ORI region
-Newly synthesized DNA also anchored to membrane
-Cell elongates until ~2 times its original size and two has two chromosomes on
opposite ends of the cell
-Cell splits in two
Quiescent stem cells, function
Permanently arrested in G0 phase. In adults: can replace non-reproducing
specialized cells) ex adult skeletal muscle/myofiber)
Steps of quiescent stem cell to myofiber
-Activated (reenter cell cycle)
-Proliferative (look over this one)
-Commitment to differentiation
-Fusion into myotube (precursor of myofiber)
-Myofiber
steps of cell cycle
G1 phase
S phase
G2 phase
M phase
~G0 phase~ perhaps
G1 phase
growth phase, prepares cell for dna synthesis
s phase
cell undergoes dna replication
g2 phase
growth phase, cell prepares for division
M phase
mitosis and cytokinesis
,cells in permanent g0 phase
eye lens, nerve, mature muscle cells
binary fission is common to
bacteria, archaea, mitochondria, chloroplasts
Satellite Stem Cells
quiescent stem cells that specifically are activated to replace injured muscle fibers
Walter Flemming
Discovered stages of mitosis from salamanders
During interphase, the genetic material of a typical eukaryotic cell is
chromatin fiber
genetic material during s phase
sister chromatids are synthesized (including centromere) but chromosomes don't
actually compact until M phase (46 X-shaped not linear chromosomes / 92
chromatids)
chromatids
chromosome in duplicated state
# chromosomes and chromatids in human before & after mitosis, meiosis I, and
meiosis II
Mitosis
Before: 46, 92
After: 46, 46
Meiosis I
Before: 46, 92,
After: 23, 46
Meiosis II
Before: 23, 46
After: 23, 23
https://datbootcamp.com/biology-strategy/chromosome-and-chromatid-numbers-duri
ng-mitosis-and-meiosis/
genetic material during interphase
chromatin fiber, can't identify specific chromosomes
prophase (mitosis)
identical sister chromatids apparent
centrosomes (microtubules) form mitotic spindle and positioned at opposite ends of
the cell
, centromere vs centrosome
centromere: holds together two sister chromatids into 1 chromosome
centrosome: hold together mitotic spindles
prometaphase
fragmentation of nuclear envelope allows mitotic spindle to attach to kinetochores on
centromeres
kinetochores
The structures on sister chromatids where microtubules attach
1) some microtubules attach directly and pull
2) some k.c are polar and repel the sides of the cell from each other
metaphase (mitosis)
chromosomes line up along middle of metaphase plate, facilitated by kinetochore
microtubules attaching to the kinetochores of each sister chromatid
anaphase (mitosis)
kinetochore microtubules shorten and pull apart chromosomes
polar microtubules repel each other and help elongate the cell
equal segregation of chromosomes (or stop)
telophase (mitosis)
nuclear envelope reforms giving 2 new daughter nuclei within the cell
chromosomes decondense
spindle microtubules depolymerized
end of mitosis
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