unit 4 Flashcards
cell communication & cell cycle (33 cards)
define the cell cycle
consists of many critical events: starting with the cell’s formation from the division of a parent cell and ending with its own division into two daughter cells
two main phases of the cell cycle:
interphase and mitotic phase (M phase)
the three subphases of interphase:
G1 phase (“first gap”), S phase (“synthesis”), and G2 phase (“second gap”)
define “interphase”
cell growth and copying of chromosomes in preparation for cell division
define “mitotic phase (M phase)”
the division of the cell into two identical daughter cells
define “G1 phase (‘first gap”)”
cell grows in size and begins doubling its number of organelles
define “S phase (“synthesis”)”
cells replicate their DNA, producing two copies of each chromosome. the two copies are attached to one another as sister chromatids
define “G2 phase (“second gap”)”
cell continues to grow and prepares for cell division (M phase)
at the end of interphase…
- nuclear envelope encloses the nucleus
- chromosomes, duplicated during S phase, cannot be seen individually because they have not yet condensed
- the centrosome has duplicated to form two centrosomes
- each centrosome is made up of a pair of centrioles
- centrosomes organize microtubules into the mitotic spindle, which controls many of the events that take place during mitosis
after interphase…
cells enter the mitotic (cell division) phase
mitotic phase consists of:
mitosis and cytokinesis
define “mitosis”
the division of the nucleus
define “cytokinsesis”
the division of the cytoplasm and the formation of two daughter cells
the five subphases of mitosis:
PMAT: prophase, metaphase, anaphase, and telophase
after mitosis…
the cell splits into two individual daughter cells via cytokinesis
during prophase…
the chromatin become tightly coiled and condense into discrete chromosomes
the duplicated chromosomes are attached to one another as…
two sister chromatids
the two sister chromatids are joined together at…
a narrow region of the chromosome called the centromere
each of the two sister chromatids contain a protein structure called..
a kinetochore found a opposite sides of each centromere
during prophase & prometaphase…
- chromosomes condense
- nuclear envelope surrounding the nucleus breaks down
- centrosomes move to opposite poles of the cell
- mitotic spindle begins to form and some of the microtubules attach to the kinetochores, becoming kinetochore microtubules
during metaphase…
the chromosomes align at the metaphase plate, a plane that is equidistant between the spindle’s two poles
during anaphase…
- kinetochore microtubules shorten, which pull apart the sister chromatids
- the two liberated daughter chromosomes move to opposite ends of the cell
during telophase…
- nuclear envelope reforms around each new set of chromosomes, creating two daughter nuclei
- chromosomes begin to uncondense
- spindle microtubules break down
during cytokinesis…
- in animal cells, a cleavage furrow forms and pinches the cell in two
- in plant cells, a cell plate forms and creates a cell wall that separates the cytoplasm of the two cells
