Cell division Flashcards
What is cell division?
- Cell division is the process by which new cells are
formed for growth, repair, and replacement in the
body.
What is the cell cycle?
- The cell cycle is an ordered sequence of events that
extends from the time a cell is first formed from a
dividing parent cell until its own division.
What is the purpose of mitosis and meiosis?
- The purpose of mitosis is cell regeneration,
growth, and asexual reproduction,while the
purpose of meiosis is the production of gametes
for sexual reproduction.
What’s the difference between meisosis and mitosis?
- There are two kinds of cell division: mitosis and
meiosis. What’s the Difference? Mitosis produces
two genetically identical “daughter” cells from a
single “parent” cell, whereas meiosis produces cells
that are genetically unique from the parent and
contain only half as much DNA.
What are haploid and diploid cells?
Haploid cells contain only one set of Chromosomes
(n). Diploid, as the name indicates, contains two sets
of chromosomes (2n). Haploid cells are formed by
the process of meiosis. Diploid cells undergo
mitosis. In the higher organism, such as humans,
haploid cells are only used for sex cells.
Whait is mitosis?
Mitosis consists of four basic phases: prophase,
metaphase, anaphase, and telophase. Some textbooks
list five, breaking prophase into an early phase (called
prophase) and a late phase (called prometaphase)
What are the phases of mitosis?
prophase, metaphase, anaphase and
telophase, and cytokinesis.
What is prophase in mitosis?
- During prophase, the chromosomes condense and
centrosomes move to opposite sides of the
nucleus, initiating formation of the mitotic spindle.
Breakdown of the nuclear envelope
What is metaphase in mitosis?
- In metaphase, the spindle has captured all the
chromosomes and lined them up at the middle of
the cell, ready to divide. All the chromosomes align
at the metaphase plate (not a physical structure,
just a term for the plane where the chromosomes
line up).
What is anaphase in mitosis?
In anaphase, the sister chromatids separate from each
other and are pulled towards opposite ends of the cell.
The protein “glue” that holds the sister chromatids
together is broken down, allowing them to separate.
Each is now its own chromosome. The chromosomes
of each pair are pulled towards opposite ends of the
cell.
What is telophase in mitosis?
In telophase, the cell is nearly done dividing, and it
starts to re-establish its normal structures as cytokinesis
(division of the cell contents) takes place. The mitotic
spindle is broken down into its building blocks. Two
new nuclei form, one for each set of chromosomes.
Nuclear membranes and nucleoli reappear.
What is cytokinesis?
Cytokinesis is the physical process of cell division,
which divides the cytoplasm of a parental cell into two
daughter cells. It occurs concurrently with two types of
nuclear division called mitosis and meiosis, which occur
in animal cells.
How is cytokinesis in animals versus plants?
Animals:
at equator, ring of actin filaments constrict.
plasma membrane starts to shrink forming cleavage furrow.
called contractile ring mechanism.
Plant:
vesicles cluster and fuse.
2 new membranes lengthen and cellulose is deposited between them.
cell walls begin to form.
called cell plate formation.
What is meiosis?
There are two divisions in meiosis; the first division is
meiosis I: the number of cells is doubled but the
number of chromosomes is not. This results in 1/2 as
many chromosomes per cell. The second division is
meiosis II: this division is like mitosis; the number of
chromosomes does not get reduced.
What is meiosis I and meiosis II?
Meiosis I begins with one diploid parent cell and ends
with two haploid daughter cells. This results in halving
the number of chromosomes in each cell. Meiosis II
starts with two haploid parent cells and ends with four
haploid daughter cells. This maintains the number of
chromosomes in each cell.
