Biology Chapter 13 Meiosis and Sexual Life Cycles
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| 353490906 | Genetics | The scientific study of heredity and variation | 0 | |
| 353490907 | Heredity | The transmission of traits from one generation to the next | 1 | |
| 353490908 | Variation | Differences between members of the same species | 2 | |
| 353490909 | Gene | A discreet unit of heredity information consisting of a specific nucleotide sequence in DNA (or RN, in some viruses) | 3 | |
| 353490910 | Locus | A specific place along the length of a chromosome where a given gene is located. A location on a certain chromosome. | 4 | |
| 353490911 | Asexual reproduction | A single individual passes genes to its offspring without the fusion of gametes. | 5 | |
| 353490912 | Clone | A group of genetically identical individuals from the same parent. A lineage of genetically identical individuals or cells. | 6 | |
| 353490913 | Sexual reproduction | Two parents give rise to offspring that have unique combinations of genes inherited from the two parents via the gametes. | 7 | |
| 353490914 | Somatic cells | 2n body - produce more somatic cells for growth and repair (mitosis). | 8 | |
| 353490915 | Germ cells | 2n reproductive - produce haploid (n) gametes to produce a new individual (meiosis). | 9 | |
| 353490916 | Life cycle | The generation to generation sequence of stages in the reproductive history of an organism. | 10 | |
| 353490917 | Human somatic cells | have 23 pairs of chromosomes | 11 | |
| 353490918 | Karyotype | An ordered display of the pairs of chromosomes from a cell. A display of the chromosome pairs of a cell arranged by size and shape. | 12 | |
| 353490919 | 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. Also called homologs. | 13 | |
| 353490920 | Sex chromosome | A chromosome responsible for determining the sex of an individual and are called X and Y. | 14 | |
| 353490921 | Human females | have a homologous pair of X chromosomes (XX). | 15 | |
| 353490922 | Human males | have one X and one Y chromosome (XY). | 16 | |
| 353490923 | Autosome | A chromosome that is not directly involved in determining sex, not a sex chromosome, the remaining 22 pairs of chromosomes. | 17 | |
| 353490924 | Diploid cell | A cell containing two sets of chromosomes (2n), one set from each parent. | 18 | |
| 353490925 | Humans | The diploid number is 46 (2n=46) and the haploid number is 23 (n=23). | 19 | |
| 353490926 | Haploid cell | A cell containing only one set of chromosomes (n). A gamete contains a single set of chromosomes. | 20 | |
| 353490927 | Ovum | An unfertilized female egg cell, the sex chromosome is X. | 21 | |
| 353490928 | Sperm | A male gamete, the sex chromosome may either be X or Y. | 22 | |
| 353490929 | Fertilization | The union of haploid gametes (sperm and egg) to produce a diploid zygote. | 23 | |
| 353490930 | Zygote | The diploid cell produced by the union of haploid gametes during fertilization; a fertilized egg. It has one set of chromosomes from each parent. | 24 | |
| 353490931 | Sexual maturity | The ovaries and testes produce haploid gametes. | 25 | |
| 353490932 | Sporophyte | In organisms (plants and some algae) that have alternation of generations, the multicellular diploid form that results from the union of gametes. The diploid organism makes haploid spores by meiosis. | 26 | |
| 353490933 | Gametophyte | In organisms (plants and some algae) that have alternation of generations, the multicellular haploid form that produces haploid gametes by mitosis. | 27 | |
| 353490934 | 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. | 28 | |
| 353490935 | Meiosis I | The first division of a two-stage process of cell division in sexually reproducing organisms that results in cells with half the number of chromosome sets as the original cell. Homologs pair up and separate, resulting in two haploid daughter cells with replicated chromosomes. | 29 | |
| 353490936 | Meiosis II | The second division of a two-stage process of cell division in sexually reproducing organisms that results in cells with half the number of chromosome sets as the original cell. Sister chromatids separate. | 30 | |
| 353490937 | Four haploid daughter cells | The result of meiosis I and meiosis II. | 31 | |
| 353490938 | Synapsis | Homologous chromosomes loosely pair up, aligned gene by gene during prophase I of meiosis. | 32 | |
| 353490939 | Crossing over | The reciprocal exchange of genetic material between non-sister chromatids during prophase I of meiosis. It produces recombinant chromosomes, which combine DNA inherited from each parent. | 33 | |
| 353490940 | Tetrad | A group of four chromatids. | 34 | |
| 353490941 | Chiasmata | a cross-shaped configuration (X-shaped regions) of paired chromatids where crossing over occurred in prophase I of meiosis. | 35 | |
| 353490942 | Prophase I | Chromosomes begin to condense; synapsis occurs, crossing over occurs, and it occupies more than 90% of the time required for meiosis. | 36 | |
| 353490943 | Metaphase I | Homologous chromosomes randomly line up at the spindle equator in a process known as "random assortment"; this is another source of variation. | 37 | |
| 353490944 | Anaphase I | Pairs of homologous chromosomes separate, one chromosome moves toward each pole, guided by the spindle apparatus, sister chromatids remain attached at the centromere and move as one unit toward the pole. | 38 | |
| 353490945 | Telophase I and Cytokinesis | Each half of the cell has a haploid set of chromosomes; each chromosome still consists of two sister chromatids. No chromosome replication occurs between the end of meiosis I and the beginning of meiosis II because the chromosomes are already replicated. The result is two haploid cells. | 39 | |
| 353490946 | Prophase II | A spindle apparatus forms and the chromosomes (each still composed of two chromatids) move toward the metaphase plate. Chromosomes condense. | 40 | |
| 353490947 | Metaphase II | The sister chromatids (no longer genetically identical) are arranged at the metaphase plate and the kinetochores of sister chromatids attach to microtubules extending from opposite poles. | 41 | |
| 353490948 | Anaphase II | The sister chromatids separate and are now renamed daughter chromosomes. | 42 | |
| 353490949 | Telophase II and Cytokinesis | Nuclei form and the chromosomes begin decondensing. The cytoplasm separates. The result is four daughter cells each with a haploid set of unreplicated chromosomes. Each daughter cell is genetically distinct from the others and from the parent cell. | 43 | |
| 353490950 | Allele | Any of the alternative versions of a gene that may produce distinguishable phenotypic effects. Mutations of different versions of genes. | 44 | |
| 353490951 | Independent assortment of chromosomes, synapsis and crossing over, and random fertilization | Three mechanisms contribute to genetic variation. | 45 | |
| 353490952 | Independent assortment of chromosomes | Homologous pairs of chromosomes orient randomly at metaphase I of meiosis. Each pair of chromosomes sorts maternal and paternal homologues into daughter cells independently of other pairs. The number of combinations possible when chromosomes assort independently into gametes is 2ⁿ, where n is the haploid number. For humans, (n=23), there are more than 8 million possible combinations of chromosomes. | 46 | |
| 353490953 | 2 | If a cell undergoes Meiosis I, how many cells result? | 47 | |
| 353490954 | 4 | If a cell undergoes Meiosis II, how many cells result? | 48 | |
| 353490955 | Gametogenesis | The formation of male and female sex cells (n) or gametes from germ cells (2n). The process by which gametes are produced. Gamete formation. | 49 | |
| 353490956 | Oogenesis | The process in the ovary that results in the production of female gametes - one functional egg per oogonium. | 50 | |
| 353490957 | Spermatogenesis | The continuous and prolific production of mature sperm cells in the testis - four functional sperm per spermatogonium (diploid reproductive cell). | 51 | |
| 353490958 | Spermatogonium | A cell that divides mitotically to form spermatocytes. | 52 | |
| 353490959 | Oogonium | A cell that divides mitotically to form oocytes. | 53 | |
| 353490960 | Phenotype | The observable physical and physiological traits of an organism, which are determined by its genetic makeup. | 54 | |
| 353490961 | Cell number | 1 → 2 → 4 1 → meiosis I → meiosis II | 55 | |
| 353490962 | Chromosome number | 2n → n → n 2n → meiosis I → meiosis II | 56 |
