Flashcards in Mitosis and Meiosis Questions Deck (33)
what is the process of mitosis?
During Mitosis, the pairs of chromatids condense and attach to fibers that pull sister chromatids to opposite side of the cell. The cell then divides during cytokinesis to produce 2 identical daughter cells.
What is the process of meiosis?
Each cell in the process of meiosis involves the cell growing, dividing, splitting, and dividing again in order to produce 4 haploid daughter cells in the end.
Which cells undergo Mitosis?
Autosomal cells (asexual reproduction) in animals, somatic cells divide by mitosis for the purpose of growth, repair, and replacement.
Which cells undergo meiosis?
germ cells only (sperm and egg) which is key to sexual reproduction.
Describe the parent cell in mitosis
The parent cells are diploid 2n
The daughter cells are also diploid and identical to the parent.
When is DNA replicated for mitosis and how many times does replication and nuclear division occur for mitosis?
Replication (chromosomes doubled)occurs during S phase of interphase. Like nuclear division, it only happens once.
What happens during nuclear division in mitosis?
The nucleus divides into 2 identical nuclei.
Describe the parent cell in meiosis
The parent cell is haploid, the daughter cells are 4 haploid and are different (half their parent)
Does meiosis reduce the number of chromosomes?
Yes, meiosis is a type of cell division that reduces the number of chromosomes in the parent cell by half and produce 4 gamete cells
Describe meiosis I
a diploid germ cell replicated its chromosomes and forms a tetrad (pairs of duplicated homo. chrom.); each duplicated homologous chromosomes is separated from its partner.
Describe Meiosis II
In meiosis II, two haploid cells divide; just like mitosis, sister chromatids are separated (reduction division)
What is the main difference between Mitosis and Meiosis?
Meiosis has two rounds of genetic separation and cellular division while mitosis only has one of each. In meiosis, homologous chromosomes separate leading to daughter cells that are not identical. In mitosis, the daughter cells are identical to the parent as well as to each other.
When is genetic variation introduced during meiosis?
Metaphase I & II
Mitosis in Prophase
Chromatin condenses down to form chromosomes. The nuclear envelope breaks down and disappears, centrosomes appear near the middle of the cell and move toward the poles of the cell. Spindle fibers form.
Mitosis in Metaphase
Where chromosomes line up in the middle of the cell.
Mitosis in Anaphase
Begins when the chromosomes begin to move apart, ends when the chromosomes reach the poles of the cell and stop moving
Mitosis in Telophase
Chromosomes de-condenses and unwinds back into chromatin, the nuclear envelope reforms, centrosomes break down, spindle fibers break down
What is cytokinesis?
Occurs during telophase and is when the cell splits into two daughter cells with identical genetic information
What are the 2 main purposes of meiosis I?
It is the reduction division, so it reduces the number of chromosomes in half making the daughter cells haploid (when the parent cells are diploid)
AND it is during meiosis I that most of the genetic recombination occurs
Meiosis I in Prophase I
Cross-over happens in the phase, similar to mitosis. The difference is what the chromosomes are doing with themselves.
Meiosis I in Metaphase I
Tetrads line up at the equator. The spindle has completely formed. (genetic variability introduced)
Meiosis I in Anaphase I
Tetrads pull apart and chromosomes with two chromatids move toward the poles.
(homologous pairs separate)
Meiosis I in Telophase I
Chromosomes with two chromatids de-condense and a nuclear envelope reforms around them. Each nucleus is now haploid.
Why go through meiosis II?
At the end of meiosis I, each chromosome still had two chromatids. That is double the amount of DNA that a cell should have. So the reason to go through meiosis II is to reduce the amount of DNA back to normal.
*each daughter cell has only one chromatid per chromosome*
Meiosis II in Prophase II
Chromosomes with 2 chromatids become visible as they condense
Meiosis II in Metaphase II
Chromosomes with two chromatids line up at the equator. The spindle is fully formed (genetic variability introduced)
Meiosis II in Anaphase II
Chromosomes spilt, so that a chromosome with only 1 chromatid head toward the each pole
Meiosis II in Telophase II
Chromosomes with only one chromatid de-condense and get surrounded by new nuclear envelopes.
End results of Meiosis II
The four daughter cells are now all haploid and have the right amount of DNA. They are ready to develop into sperm or eggs now