Cellular Division - AP Biology

Metaphase is the second phase of mitosis in which spindle fibers move the chromosomes to the center of the cell where they are aligned. Prophase is the first phase of mitosis, anaphase is the third phase, and telophase is the fourth and final phase.

Anaphase is the third phase of mitosis in which each sister chromatids of each chromosome toward the opposite poles of the cell. Prophase is the first phase of mitosis, metaphase is the second phase, and telophase is the fourth and final phase.

Gametes are haploid sex cells produced from germ line cells during mitosis. During human fertilization, male and female haploid gametes fuse to form a diploid zygote.

Gametes are haploid sex cells produced from germ line cells during mitosis. During human fertilization, male and female haploid gametes fuse to form a diploid zygote.

Interphase in the cell cycle encompasses the G1, S, and G2 phases, as it shows the period of growth and DNA replication that a cell must go through to prepare for mitosis. Cell division, which occurs during the M phase, is the only portion of the cell cycle that is not included in interphase.

Because they do not divide, central nervous system nerve cells do not need to experience growth (G1 and G2 phases), DNA replication (S phase), or mitosis (M phase). As a result, they spend most of their lives arrested in G0, a resting phase.

Gametes are haploid sex cells produced from germ line cells during mitosis. During human fertilization, male and female haploid gametes fuse to form a diploid zygote.

Prophase is the first phase of mitosis in which chromatin coils and forms chromosomes, the spindle apparatus begins to form, and the nuclear membrane breaks down. The second, third, and fourth phases are metaphase, anaphase, and telophase, respectively.

The laws of inheritance include the laws of segregation (each gamete receives only one copy of each gene from its parent), dominance (in a heterozygote individual, only the dominant allele will influence the phenotype), and independent assortment (inheritance of one gene does not influence inheritance of another gene)

The law of independent assortment states that inheritance of one gene does not influence inheritance of another gene. Thus, inheritance of seed color does not affect the inheritance of seed shape.

According to the Law of Segregation, each gamete receives one allele for each gene from each parent. During Meiosis, each parent’s two copies of each allele are separated from each other, then the gamete receives one copy of each allele from each parent (for a total of two alleles).

This is the definition of the law of independent assortment; during meiosis, the inheritance of one gene does not influence whether another, separate gene will also be inherited by that gamete.

According to the Law of Dominance, each individual has two alleles for each trait and only the dominant allele contributes to the phenotype.

According to the Law of Segregation, during Meiosis, homologous chromosomes segregate into different gametes.

Recombination or crossing over happens primarily in Prophase I. In anaphase and telophase, the DNA strands are separated and cannot recombine. In metaphase, homologous chromosomes line up with each other, but do not recombine.

Mitosis and meiosis share many procedural similarities, however, it is important to remember that mitosis makes identical cells while meiosis allows genetic variability between cells.

Meiosis takes place in sex cells, which are capable of creating millions of different variations of offspring. Mitosis takes place in normal cells involved in growth and regeneration within a single, uniform organism.

Meiosis includes two divisions, resulting in two pairs of haploid cells, while mitosis only involves a single division.

Both meiotic and mitotic divisions share the same phases, though there are some differences in the activity of these phases. Mutation can, and does, occur in both mitosis and meiosis. Crossing over, however, is unique to meiosis.

Crossing over ensures genetic variability as it results in daughter cells with different genetic material than their parent cells. This occurs during meiosis I, but is not seen in mitosis or meiosis II.

Both mitosis and meiosis occur in humans. Somatic cells (body cells) divide via mitosis, while gametes (sex cells) divide via meiosis. Because of actions such as crossing over, meiosis results in a higher genetic variability than mitosis.

Prokaryotes, such as bacteria, reproduce asexually, and are incapable of meiosis.