Mitosis Flashcards
Interphase
G1, S (DNA synthesis), G2
Mitotic (M) phase
Mitosis, cytokinesis
phases of the cell cycle
are an ordered series of events, promotes cell growth and division to produce daughter cells
Mitosis is
the division of the nucleuses that produces two identical daughter cells
Most of the time, the cell is in
Q0 or G0 phase (snoozing/sleeping, letting all the organelles do their jobs)
Interphase is
cell growth and copying of chromosomes in preparation for cell division (cell spends a lot of time here, 90% of the cell cycle)
Interphase is for
the cell to grow and replicate its DNA and check pre-existing DNA, and check for mutations of the cell
S phase is when
chromosomes/DNA is duplicated during this phase
Cytokinesis
the division of the cytoplasm
Mitosis includes
prophase, prometaphase, metaphase, anaphase, telophase
Cytokinesis is well underway by
telophase (DNA has split, now the cytoplasm needs to)
Kariokinesis
prophase through Telophase
Prophase, the first stage of mitosis
- chromosomes condense and become visible (chromatins wound very tightly)
- spindle fibers emerge from centrosomes
- nuclear envelope breaks down (disinigrates and put in vesicles)
- nucleus disappears
Prometaphase, second stage of mitosis
- chromosomes continue to condense
- Kinetochores appear at the centromeres
- Mitotic spindle microtubules attach to kinetochores
- centrosomes move towards opposite poles
Kinetochores are
a protein complex that sits on top of centrosomes. Generate attachments of sister chromatids to stay attached, is also where spindle fibers come out of, facing opposite poles
Metaphase, third stage in mitosis
- mitotic spindle in fully developed, centrosomes are at opposite poles of the cell
- chromosomes are lined up at the metaphase plate
- each sister chromatid is attached to a spindle fiber originating from opposite poles
metaphase plate
a section in the equatorial plane of the metaphase spindle having the chromosomes oriented upon it.
Anaphase, fourth step of mitosis
- cohesion proteins binding the sister chromatids together break down
- sister chromatids (now called chromosomes) are pulled toward opposite poles
- non-kinetochore spindle fibers lengthen, elongating the cell
- sister chromatids separate and move along the kinechore microtubules toward opposite ends of the cell
- the microtubules shorten by depolymerizing at their kinetochore ends
the cell needs to be elongated for
the cell to be ready to split into daughter cells
Telophase, fifth step in mitosis
- chromosomes arrive at opposite poles and begin to decondense
- nuclear enevelope material surrounds each set of chromosomes
- mitotic spindle fibers break down
Cytokinesis, sixth step in mitosis
- animal cells: a cleavage furrow separates the daughter cells
- plant cells: a cell plate separates the daughter cells
During cytokinesis in animal cells
a ring of actin filaments forms at the metaphase plate. the ring contracts, forming a cleavage furrow, which divides the cell in two.
During cytokinesis in plant cells
golgi vesicles coalesce at the former metaphase plate, forming a phragmoplast. A cell plate formed by the fusion of the vesicles of the phragmoplast grows from the center toward the cell walls, and the membranes of the vesicles fuse to form a plasma membrane that divides the cell in two.
