Cell division - reps

Question 1

What are 3 differences between Meiosis and Mitosis

Answer 1

Mitosis makes two daughter cells with an identical number of chromosomes (2n) to the parent (2n). In comparison, Meiosis makes 4 daughter cells genetically different from each other that only have a haploid number of chromosomes (n).

Mitosis makes somatic (body) cells while meiosis makes germ (gametes) cells

Mitosis is a cycle, Meiosis is not and makes daughter cells for reproduction

Question 2

Think hard on this one: Crossing over occurs during what phase?

Answer 2

Prophase I of Meiosis I

Question 3

Does crossover happen in Meiosis, Mitosis, or both?

Answer 3

Meiosis

Question 4

Stages in Mitosis

Answer 4

Mitotic phase - prophase, metaphase, anaphase and telophase,
Cytokinesis - cytoplasm divides

Question 5

Stages in Meiosis

Answer 5

Meiosis I:
Prophase I
Metaphase I
Anaphase I
Telophase I

Meiosis II:
Prophase II
Metaphase II
Anaphase II
Telophase II

Question 6

Prophase I

Answer 6

Chromosomes condense and become visible, nuclear envelope fragments. Homologous chromosomes form a tetrad. Crossing over occurs and chiasmata forms between non-sister chromatids. Spindle fibers emerge from centrosome.

Question 7

Prometaphase I

Answer 7

Spindle fibers attach to the chromosomes at points along the chromosomes called centromeres. While this is happening, the chromosomes continue to condense.

Question 8

Metaphase I

Answer 8

Maternal and paternal versions of the same chromosome (homologous chromosomes) align along the equator of the cell. A process called independent assortment occurs – this is when maternal and paternal chromosomes line up and randomly align themselves on either side of the equator. This in turn determines which gamete chromosomes are allocated to, which leads to genetic diversity among offspring.

Question 9

Anaphase I

Answer 9

In anaphase I, the homologues are pulled apart and move apart to opposite ends of the cell. The sister chromatids of each chromosome, however, remain attached to one another and don’t come apart.

Question 10

Telophase I

Answer 10

Finally, in telophase I, the chromosomes arrive at opposite poles of the cell. In some organisms, the nuclear membrane re-forms and the chromosomes decondense, although in others, this step is skipped—since cells will soon go through another round of division, meiosis II
Cytokinesis usually occurs at the same time as telophase I, forming two haploid daughter cells.

Question 11

Prophase II

Answer 11

During prophase II, chromosomes condense and the nuclear envelope breaks down, if needed. The centrosomes move apart, the spindle forms between them, and the spindle microtubules begin to capture chromosomes.

Question 12

Metaphase II

Answer 12

In metaphase II, the chromosomes line up individually along the metaphase plate.

Question 13

Anaphase II

Answer 13

In anaphase II, the sister chromatids separate and are pulled towards opposite poles of the cell.

Question 14

Telophase II

Answer 14

In telophase II, nuclear membranes form around each set of chromosomes, and the chromosomes decondense. Cytokinesis splits the chromosome sets into new cells, forming the final products of meiosis: four haploid cells in which each chromosome has just one chromatid. In humans, the products of meiosis are sperm or egg cells.

Question 15

Two ways that Meiosis mixes and matches genes

Answer 15

Crossing over: Homologues connect and exchange genetic material randomly

Random orientation of homologue pairs: The random orientation of homologue pairs in metaphase I allows for the production of gametes with many different assortments of homologous chromosomes.