Chapter 13
Meiosis and Sexual Life Cycles
Vocabulary: heredity, variation, genetics, genes, gametes, asexual reproduction, clone, sexual reproduction, life cycle, karyotypes, homologous chromosomes, sex chromosomes, autosomes, diploid cell, haploid cell, zygote, fertilization, meiosis, alternation of generations, sporophyte, spores, gametophyte, meiosis I, meiosis II, synapsis, crossing over, chiasma, recombinant chromosomes, independent assortment
Objectives:
After attending lectures and studying the chapter, the student should be able to:
1. Relating to cell division involving meiosis (meiosis + cytokinesis):
a. Define meiosis.
b. Explain why meiosis is sometimes considered "reduction division".
c. State what 1 diploid cell becomes after meiosis plus cytokinesis.
d. State the gametes in the human male and human female and describe the role of gametes in the human life cycle.
e. State the reason humans undergo cell division involving meiosis.
f. Define gametogenesis and distinguish between human spermatogenesis and oogenesis.
g. State which cells in humans undergo cell division involving meiosis.
h. Describe the 4 stages of meiosis I and the 4 stages of meiosis II.
2. Define genetic recombination.
3. Explain how recombination leads to genetic variation in a population and how genetic variation relates to evolution.
4. Explain how mating leads to recombination in eukaryotic organisms.
5. Briefly distinguish between the three types of sexual life cycles (p. 252) and their major differences. Use the examples: animal, plants, and multicellular fungi
6. Relating to recombination that occurs as a result of meiosis in eukaryotic organisms:
a. Describe segregation, state when it occurs during meiosis, and explain how it can lead to recombination.
b. Describe independent assortment and explain how it can lead to recombination.
c. Describe the process of crossing over (including the formation of tetrads, the synaptonemal complex, and chiasmata), state when during meiosis crossing over occurs, and explain how crossing over causes recombination.
| 3358091842 | Heredity | The transmission of traits from one generation to the next | 0 | |
| 3358091843 | Variation | Differences between members of the same species | 1 | |
| 3358091844 | Genetics | The scientific study of heredity and hereditary variation | 2 | |
| 3358091845 | Genes | A discrete unit of hereditary information consisting of a specific nucleotide sequence in DNA (or RNA, in some viruses). | 3 | |
| 3358091846 | Gametes | A haploid reproductive cell, such as an egg or a sperm. They unite during sexual reproduction to produce a diploid zygote. | 4 | |
| 3358091847 | Somatic cells | Any cell in a multicellular organism except a sperm or egg or their precursor | 5 | |
| 3358091848 | Locus | A specific place along the length of a chromosome where a given gene is located | 6 | |
| 3358091849 | Asexual reproduction | Without the fusion of gametes. The generation of offspring from a single parent that occurs without the fusion of gametes. In most cases the offspring are genetically identical to the parent. | 7 | |
| 3358091850 | Clone | A lineage of genetically identical individuals or cells. | 8 | |
| 3358091851 | Sexual reproduction | A type of reproduction in which two parents give rise to offspring that have unique combinations of genes inherited from the gametes of the parents. | 9 | |
| 3358091852 | Life cycle | The generation-to-generation sequence of stages in the reproductive history of an organism.. | 10 | |
| 3358091853 | Karyotope | A display of the chromosome pairs of a cell arranged by size and shape. | 11 | |
| 3358091854 | Homologous chromosomes | A pair of chromosomes of the same length, centromere position, and staining pattern that possess genes for the same characters at corresponding loci. One homologous chromosome is inherited from the organism's father, the other from the mother. Also called homologs, or a homologous pair. | 12 | |
| 3358091855 | Sex chromosomes | A chromosome responsible for determining the sex of an individual | 13 | |
| 3358091856 | Autosomes | A chromosome that is not directly involved in determining sex; not a sex chromosome. | 14 | |
| 3358091857 | Diploid cells | A cell containing two sets of chromosomes (2n), one set inherited from each parent | 15 | |
| 3358091858 | Haploid cells | A cell containing only one set of chromosomes (n). | 16 | |
| 3358091859 | Zygote | The diploid product of the union of haploid gametes during fertilization; a fertilized egg. | 17 | |
| 3358091860 | Meiosis | A modified type of cell division in sexually reproducing organisms consisting of two rounds of cell division but only one round of DNA replication. It results in cells with half the number of chromosome sets as the original cell. | 18 | |
| 3358091861 | Alternation of generations | A life cycle in which there is both a multicellular diploid form, the sporophyte, and a multicellular haploid form, the gametophyte; characteristic of plants and some algae. | 19 | |
| 3358091862 | Meiosis I | Homologous chromosomes separate | 20 | |
| 3358091863 | Recombinant chromosomes | A chromosome created when crossing over combines DNA from two parents into a single chromsome | 21 | |
| 3358091864 | The diploid number for fruit flies is 8, and the diploid number for grasshoppers is 46. If no crossing over took place, would the genetic variation among offspring from a given pair of parents be greater in fruit flies or grasshoppers? | ... | 22 | |
| 3358091865 | Independent Assortment | ..., Independent segregation of genes during the formation of gametes | 23 | |
| 3358091866 | Independent assortment | One of Mendel's principles that states that genes for different traits can segregate independently during the formation of gametes | 24 | |
| 3358091867 | Meiosis II | sister chromatids separate | 25 | |
| 3358091868 | Haploid | A cell containing only one set of chromosomes (half) | 26 | |
| 3358091869 | Diploid | A cell containing two sets of chromosomes (2n), one set inherited from each parent | 27 | |
| 3358091870 | Mitosis | A cell splitting to form copies of itself | 28 | |
| 3358091871 | Which life cycle stage is found in plants but not animals? | multicellular haploid | 29 | |
| 3358091872 | Homologous chromosomes move toward opposite poles of a dividing cell during | meiosis I. | 30 | |
| 3358091873 | Meiosis II is similar to mitosis in that | sister chromatids separate during anaphase. | 31 | |
| 3358091874 | f the DNA content of a diploid cell in the G1 phase of the cell cycle is x, then the DNA content of the same cell at metaphase of meiosis I would be | 2x. | 32 | |
| 3358091875 | How many different combinations of maternal and paternal chromosomes can be packaged in gametes made by an organism with a diploid number of 8 (2n 5 8)? | 16 | 33 | |
| 3358091876 | chiasma | The X-shaped, microscopically visible region where homologous nonsister chromatids have exchanged genetic material through crossing over during meiosis, the two homologs remaining associated due to sister chromatid cohesion. | 34 | |
| 3358091877 | crossing over | The reciprocal exchange of genetic material between nonsister chromatids during prophase I of meiosis. | 35 | |
| 3358091878 | gametophyte | In organisms (plants and some algae) that have alternation of generations, the multicellular haploid form that produces haploid gametes by mitosis. The haploid gametes unite and develop into sporophytes. | 36 | |
| 3358091879 | spore | (1) In the life cycle of a plant or alga undergoing alternation of generations, a haploid cell produced in the sporophyte by meiosis. A ___can divide by mitosis to develop into a multicellular haploid individual, the gametophyte, without fusing with another cell. (2) In fungi, a haploid cell, produced either sexually or asexually, that produces a mycelium after germination. | 37 | |
| 3358091880 | sporohyte | In organisms (plants and some algae) that have alternation of generations, the multicellular diploid form that results from the union of gametes. The sporophyte produces haploid spores by meiosis that develop into gametophytes. | 38 | |
| 3358091881 | synapsis | The pairing and physical connection of replicated homologous chromosomes during prophase I of meiosis. | 39 |
