Meiosis Flashcards
(34 cards)
Anaphase I
The phase during Meiosis I when homologous pairs move to opposite poles of the cell.
Anaphase II
The phase during Meiosis II when enzymes dissolve the centromeres and sister chromatids are pulled apart to opposite poles of the cell.
Asexual vs. Sexual Reproduction
Asexual reproduction occurs more quickly, requires less energy, and has less genetic variation than sexual reproduction. Organisms produced by asexual reproduction are also more likely to be subject to extinction due to environmental changes.
Centrioles, Spindle Fibers, Centromeres, and Kinetochores
Centrioles are organelles that aid in cell division by producing spindle fibers, which are microtubules that pull tetrads and sister chromatids apart. The centromere is the point at which sister chromatids are attached, and the kinetochore is the point on the centromere to which the spindle fibers connect.
Crossing Over
The exchange of corresponding pieces of DNA on homologous chromosomes (maternal and paternal DNA mix).
Cytokinesis I
The phase during Meiosis I when the cell’s cytoplasm splits into two and two separate cells are produced.
Cytokinesis II
The phase during Meiosis II when each of the two cells produced by Meiosis I split into two separate cells, forming an end total of 4 haploid cells.
Diploid - 2n
Having 2 chromosomes for each trait, one from each parent. n represents the number of traits, and n = 23 in humans.
Haploid - n
Having 1 chromosomes for each trait.
Fertilization
The process of combining the nucleus of the sperm cell with the nucleus of the ova, forming a diploid cell.
Fetus
A mass of cells that is an unborn organism out of sexual reproduction. A fetus is formed after fertilization occurs and a zygote forms. The zygote divides rapidly by mitosis to form a fetus.
Gametes
Sex cells, including sperm cells and egg cells (ova) in male humans and female humans, respectively. Gametes are haploid.
Gametogenesis
The process that cells undergo in order to produce sex cells (gametes) by meiosis.
Genetic Diversity
The variability in the phenotypes of a species, or set of organisms. These differences are necessary for the survival of the species, as a good number have to always be prepared for environmental changes.
Genetic Variation
Differences genetic variation that strengthen a species by helping it better prepare for environmental changes.
Homologous Chromosomes
Chromosomes that are the same size and length, pair with each other, and code for the same genes, but with a variety of expressions.
Independent Assortment
A source of genetic variation during metaphase I. Homologous chromosomes line up independently of each other, producing about 8 million different possibilities in humans.
Interphase
A large part of the cell cycle made up of G1 Phase, S Phase, and G2 Phase. During Interphase, the cell is growing and preparing for division in M Phase and Cytokinesis.
Mitosis vs. Meiosis
Mitosis has one division, while meiosis has two. The former produces two daughter cells, while the latter produces four. Mitosis daughter cells have the same number of chromosomes as the parent cell, while meiosis daughter cells have half the number. Mitosis cells are genetically identical, while, in meiosis, cells are not identical, producing genetic variation.
Meiosis I
The first round of division in meiosis, containing prophase I, metaphase I, anaphase I, telophase I, and cytokinesis I (PMATC1).
Meiosis II
The second round of division in meiosis, containing prophase II, metaphase II, anaphase II, telophase II, and cytokinesis II (PMATC2).
Metaphase I
The phase of meiosis I during which homologous pairs line up on the metaphase plate 2x2.
Metaphase II
The phase of meiosis II during which chromosomes line up single file in the middle of the cell.
Non-Disjunction
The failure of one or more pairs of homologous chromosomes or sister chromatids to separate normally during nuclear division, usually resulting in an abnormal distribution of chromosomes in the daughter nuclei.
