Mitosis / Meiosis Beads Flashcards
what is the goal of mitosis
to make an exact copy of the nucleaus
MITOSIS
G1 Interphsse
the cell increases in mass in preparation for cell division. Note that the G in G1 represents gap and the 1 represents first, so the G1 phase is the first gap phase.
MITOSIS
S Interphase
The period during which DNA is synthesized. In most cells, there is a narrow window of time during which DNA is synthesized. Note that the S represents synthesis.
MITOSIS
end of S interphase - Sister Chromatids
at the end of the S Phase they have sister chromatids
MITOSIS
G2 Interphase
The period after DNA synthesis has occurred but prior to the start of prophase. The cell synthesizes proteins and continues to increase in size. Note that the G in G2 represents gap and the 2 represents second, so the G2 phase is the second gap phase.
In the latter part of interphase:
the cell still has _______ present.
the _______ is bound by a ________ _______ and the cell’s chromosomes are the form of __________
nuclei
nucleaus, nuclear envelope, chromatid
MITOSIS
Prophase
the chromatin condenses into discrete chromosomes. The nuclear envelope breaks down and spindles form at opposite “poles” of the cell. Many consider prophase (versus interphase) to be the first true step of the mitotic process.
Name some changes that occur during Mitosis Prophase
- chromatin fibers become coiled into chromosomes with each chromosome having two chromatids joined at centromere
- the mitotic spindle, composed of microtubules and proteins, forms in the cytoplasm
- the two pair of centrioles move away from one another toward opposite ends of the cell due to lengthening of the microtubules
MITOSIS
Metaphase
the spindle fully develops and the chromosomes align at the metaphase plate (a plane that is equally distant from the two spindle poles).
Changes that occur during Mitosis Metaphase
- nuclear membrane disappears complete
- polar fibers continue to extend from the poles to center of cell
- chromosomes move randomly until they attach to polar fibers from both sides of their centromers
- chromosomes align at the metaphse plate at right angles to the spindle poles
MITOSIS
Anaphase
the paired chromosomes (sister chromatids) separate and begin moving to opposite ends (poles) of the cell. Spindle fibers not connected to chromatids lengthen and elongate the cell. At the end of anaphase, each pole contains a complete compilation of chromosomes.
MITOSIS
Telophase
the chromosomes are cordoned off into distinct new nuclei in the emerging daughter cells.
what is the goal of Meiosis
to make genetically different cells
MEIOSIS
Meiosis Interphase
Cell has grown and made copies of each chromosome
MEIOSIS
End of Interphase
same as Mitosis
MEIOSIS
Prophase I
MOST IMPORTANT STAGE
genes get mixed up (randomized) called genetic recombination. chromosomes have two sister chromatids. they cross and overlap.
MEIOSIS
Metaphase I
Tetrads align at the metaphase plate.
Note that the centromeres of homologous chromosomes are oriented toward the opposite cell poles.
MEIOSIS
Anaphase I
Chromosomes move to the opposite cell poles. Similar to mitosis, the microtubules and the kinetochore fibers interact to cause the movement.
Unlike in mitosis, the homologous chromosomes move to opposite poles yet the sister chromatids remain together.
MEIOSIS
Telophase I
The spindles continue to move the homologous chromosomes to the poles.
Once movement is complete, each pole has a haploid number of chromosomes.
In most cases, cytokinesis occurs at the same time as telophase I.
At the end of telophase I and cytokinesis, two daughter cells are produced, each with one half the number of chromosomes of the original parent cell.
MEIOSIS
INTERPHASE
NONE DUH!!
MEOSIS
Prophase 2
The nuclear membrane and nuclei break up while the spindle network appears.
The chromosomes begin migrating to the metaphase II plate (at the cell’s equator).
MEIOSIS
Metaphase 2
The chromosomes line up at the metaphase II plate at the cell’s center.
The kinetochores of the sister chromatids point toward opposite poles.
MEIOSIS
Anaphase 2
The sister chromatids separate and move toward the opposite cell poles.
MEIOSIS
Telophase 2
Distinct nuclei form at the opposite poles and cytokinesis occurs.
At the end of meiosis II, there are four daughter cells each with one half the number of chromosomes of the original parent cell.
Different from mitosis: reduced number of chromosoems (2 in each one).
Each nucleai has different chromosome in it.
MITOSIS: the cytoplasm divides, and the cell contents are seperated into two cells.
cytokinesis
MITOSIS: chromosomes become aligned along the equatorial plane of the cell
metaphase
MITOSIS: chromosome replication occurs
S Phase of interphase
MITOSIS: Migration of the daughter chromosomes to the two poles is complete
telophase
MITOSIS: what happens in anaphase?
sister chromatids seperate, and the now-daughter chromosomes move to oppsotite poles of the cell
MEIOSIS: a nuclear envelope forms around each set of chromosomes and cytokinesis occurs, prducing 4 daughter cells, each with a haploid set of chromosomes
telophase 2
the two chromosomes in each bivalent sepeate and migrate toward opposite poles
anaphase I
MEIOSIS: the maternal and paternal chromosomes of each homologous pair seperate and reach the poles of the cell, nuclear envelopes form around them, and cytokinesis follows to produce two cells
telophase I
MEIOSIS: what is the state during which the pairs of chromosomes become arranged on a plane equidistant from the poles
metaphase I
what are the mechanisms by which genetic variation is produced by meiosis
through the way the paternal and maternal chromosomes segregate; and by the process of crossing over
Name the stages of Meioss
Name the stages of Mitosis
