Metaphase II, Prophase II
Metaphase I, Metaphase II
Anaphase I, Anaphase II
Prophase II, Metaphase II
Formation of tetrads
Crossing over of non-sister chromatids
Chromosomes line up on the metaphase plate independently, not in pairs
Sister chromatids separating during anaphase
2 diploid daughter cells
4 diploid daughter cells
2 haploid daughter cells
4 haploid daughter cells
Identical strands of DNA
Since the maternal and paternal gametes fuse, they must be produced as diploid cells by meiosis, or the ploidy number will be cut in half each generation.
A large number of gametes are needed, so producing four daughter cells is more efficient.
Since the maternal and paternal gametes fuse, they must be produced as haploid cells by meiosis, or the ploidy number will double each generation.
Crossing over and independent assortment during meiosis II create a high degree of genetic variability, ensuring that at least some progeny will be successful.
They are archaic processes.
It allows for populations to adapt to environmental changes.
They produce offspring extremely quickly.
They will almost always have different offspring arise.
Anaphase produces haploid daughter cells and anaphase II results in diploid daughter cells.
Sister chromatids separated in anaphase II are different while they are identical in anaphase.
The ploidy level will be reduced in anaphase II.
Spindle fibers separate the kinetochores in chromosomes in anaphase.
Sister chromatids are on the metaphase plate in meiosis I and tetrads are on the metaphase plate in meiosis II.
Homologous chromosomes line up in meiosis I and duplicated chromosomes line up in meiosis II.
All chromatids are the exact same in meiosis I and differ in meiosis II due to independent assortment.
The ploidy level remains the same in meiosis I but will be reduced in meiosis II.
Meiosis but not mitosis.
Mitosis but not meiosis.
Both mitosis and meiosis.
Neither mitosis or meiosis.
Independent assortment of chromosomes during anaphase I creates 2^23 (greater than 8 million) possible combinations of chromosomes, plus there is added variety from crossover events.
With high DNA mutation rates, each oocyte is likely to carry at least one unique base-pair mutation.
Random deletions of chromosome arms during chiasmata formation result in 2^46 different possible combinations of deletions.
The ovary lacks DNA damage checkpoints for gametes produced during mitosis.
None. Any chromosome from my grandmother become recombined with a chromosome from my grandfather in my mother's gonad during meiosis II of gamete formation.
About 11 or 12 (1/4 of the total) since I have four grandparents.
None. Any chromosome from my grandmother become recombined with a chromosome from my grandfather in my mother's gonad during meiosis I of gamete formation.
Anywhere from 0 to 23 of my chromosomes may be those from my maternal grandmother - there is no way to predict.
Separation of chromosomes
Lengthening of newly formed daughter cells
Formation of the cleavage furrow
Alignment of the chromosomes on the metaphase plate
After DNA replication during the S phase of the cell cycle.
Once the origin of replication is complete and the septum has formed.
During crossing over in prophase I of meiosis.
When gametes fuse during fertilization.
Pairing of homologous chromosomes, crossover, sister chromatids staying together in anaphase II, and supression of DNA replication before meiosis I.
Pairing of homologous chromosomes, crossover, sister chromatids separating during anaphase II, and kinetochore microtubules.
Pairing of sister chromatids, crossover between sister chromatids, centrosomes containing centrioles, and chiasmata connecting the kinetochores to the centrosome.
Pairing of homologous chromosomes, crossover, sister chromatids staying together in anaphase I, and suppression of DNA replication during interphase between meiosis I and II.
Alternation of generations
The X and Y chromosome
A grandparent's chromosome 16 and the one which was passed down to his grandson
Mitosis lacks crossing over between homologous chromosomes and since both chromosomes are partitioned to daughters, also lacks independent assortment.
DNA damage checkpoints are more vigilant during mitosis than during meiosis.
The chromosomes are less exposed to damaging UV rays during mitosis than during meiosis.
Mitosis does add genetic diversity by similar mechanisms, but the results are less apparent since an individual organism doesn't arise from the mitotic daughter cells.
Alternation of generations
All three genes are equally likely to be separated by a crossover event, since these are randomly distributed.
The maternal chromosome will be transmitted as it is to half of the progeny.
The maternal chromosome will be transmitted as it is to all of the progeny.
Genes A and B are likely to stay together, but they are more likely to become separated from gene C since a crossover is more likely to occur in the longer space between them.
Organisms live a solitary lifestyle
When the parent organism have been successful in their habitat
Mutation rates are high
The environment is changing