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Genetics Test 1
Genetics Test 1 ppt 2
| Question | Answer |
|---|---|
| Chromatin | Complex of DNA with histone and nonhistone protein. Organized into discrete bodies called chromosomes |
| Karyotype | Number, size, and morphology of the chromosome set of a cell |
| Genome | Chromosomes in a haploid set, or all the chromosomes in a diploid nucleus |
| Centromere positions, from the middle to the end | Metacentric, submetacentric, acrocentric or sub-telocentric, telocentric |
| Fundamental difference between asexual and sexual reproduction | Sexual reproduction generates variation through genetic recombination |
| Cytokinesis | Division of cytoplasm |
| Cell cycle | Cycle of growth, mitosis, and cell division |
| Two phases of somatic cell cycle | Interphase and mitotic or dividing phase |
| What occurs during interphase? | DNA replication and synthesis of protein and nucleic acid components |
| What are the three stages of interphase? | G1, S, and G2 |
| S period | Synthesis or replication of DNA |
| G1 period | Synthesis of RNA, functional protein, and enzymes and substrates for DNA replication |
| G2 period | Synthesis of structural protein, and spindle and aster protein. High energy demand |
| Uses of cell division | Growth, replacement of cells, and wound healing |
| Five phases of mitosis | Prophase, prometaphase, metaphase, anaphase, telophase |
| Prophase | Chromatin condenses and chromosomes become visible |
| Prometaphase | Chromosomes continue condensing, nuclear membrane and nucleolus break down, centrioles migrate to poles of cell, spindle fibers extend |
| Metaphase | Spindle fibers pull chromosomes into line along metaphase plate. Order is important, and each sister chromatid is attached by spindle fibers to opposite poles of cell |
| Anaphase | Sister chromatids split and move to opposite poles of cell |
| Telophase | Fibers from centrioles break down and nuclear envelope forms around each set of chromosomes. Chromatin decondenses and nucleolus reappears |
| Spindle fibers | Microtubules consisting of proteins called tubulins. Form spindle between two pairs of centrioles |
| Aster | Microtubules radiating outward from centrioles |
| Kinetochore microtubules | Invade nuclear space and attach to kinetochores during prometaphase |
| Polar microtubules | Push against each other to move centrosomes apart |
| Kinetochore | Multiprotein disk located on the centromere that is specialized to interact with spindle fibers during mitosis |
| When does crossing over occur? | Prophase I of meiosis I |
| Synapsis | Two homologous chromosomes come into side-by-side contact to form a bivalent |
| Bivalent | Pair of homologous chromosomes held together by a complex |
| Tetrad | Two pairs of chromatids, so four future chromosomes |
| What are the 5 stages of prophase I | Leptonema, zygonema, pachynema, diplonema, and diakinesis |
| Leptonema | Chromosomes begin to coil. Pairing of homologous chromosomes |
| Zygonema | Yolk-thread. Synapsis, or the formation of the synaptonemal complex |
| Synaptonemal complex | Zipper-like structure along length of chromatids |
| Pachynema | Thick-thread. Synapsis is complete, crossing over occurs. Synapsis disassembles |
| Diplonema | Double-thread. Homologues begin to separate. Chiasma becomes apparent |
| Chiasma | Cross-shaped structure that is physical evidence of crossing over |
| Diakinesis | Across thread. Chiasmata often terminalize and tetrads become clearly visible |
| What are PARs? | Pseudoautosomal regions. Found on each end of Y chromosomes and allow sex chromosomes to pair and cross over even though they are not homologous. |
| What happens if the PAR is deleted from the short arm of the Y chromosome? | Pairing does not occur between X and Y chromosomes, so the male is fertile |
| Metaphase I of meiosis I | Tetrads align at metaphase plate |
| Anaphase I of meiosis I | Homologous chromosomes are pulled apart, but sister chromatids stay together |
| What do the daughter cells of meiosis I contain? | One of each of the homologous chromosomes. Sister chromatids are not identical |
| What does meiosis II result in? | Four unidentical haploid daughter cells |
| What does spermatogenisis result in? | Four spermatids that develop into spermatozoa |
| What does oogenisis result in? | One ovum and three polar bodies |
| Gametophyte | Haploid plant stage in which gametes are produced by meiosis (sexual) |
| Sporophyte | Diploid plant stage in which haploid spores are produced by mitosis (asexual) |
| Pistil | Female part of a flower. Includes stigma, style, and ovary |
| Stamen | Male part of a flower. Includes anther and filament |
| Megasporogenisis | Meiosis in female part of the flower that produces a megaspore |
| Megagametophyte | Cell with eight identical haploid nuclei in a common cytoplasm. Produced by megaspore undergoing three successive rounds of nuclear mitotic divisions |
| Embryo sac | Entire seven-celled megagametophyte structure. One cell becomes the egg |
| Microsporogenisis | Meiosis in male part of the flower that produces pollen grains |
| Process of microsporogenisis | Anther>four pollen sacs>diploid microspore mother cells>four haploid microspores (pollen) |
| Significance of sex | Generate genetic diversity through independent assortment, crossing over, and random fertilization |
Created by:
iragland
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