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LS LSAF Chapter 4
Mitosis, Meiosis
Term | Definition |
---|---|
Mitosis | The division of a nucleus during asexual reproduction. |
Prophase (Mitosis) | The first stage of mitosis. Nuclear membrane disappears. Chromatin is visible. Centrioles migrate to opposite sides of nucleus. Spindle forms. |
Metaphase (Mitosis) | The second phase of mitosis. Chromatin "x"s line up along the middle of the nuclear region; attached to spindle fibers. |
Anaphase (Mitosis) | The third phase of mitosis. Chromatin migrates toward centrioles along spindle fibers. |
Telophase (Mitosis) | The final step of mitosis. Nuclear membrane reappears. Chromatin becomes invisible. Centrioles and fibers dissolve. Cytokinesis. |
Cytokinesis | The division of cytoplasm at the end of mitosis. In plants, a cell plate is created which will become cell wall when division is complete. |
Sexual Reproduction | Reproduction which involves an exchange of DNA. Daughter cells are morphologically unique from parent cells. |
Asexual Reproduction | Reproduction which involves no exchange of DNA. Daughter cells are morphologically identical to parent cell. |
Morphology | Refers to the study of shape, form, genetic makeup, appearance, etc of an organism. |
S phase | "Stationary" phase. Cells carry out all life processes except reproduction. Near the end of the S phase, nuclear material is replicated. |
G1 Phase | "Growth" phase. Cells create many organelles after mitosis in order to grow to normal size. |
G2 Phase | "Growth" phase. Cells actively create many organelles before mitosis in order to prepare for division. |
Somatic Cells | Cells that have a diploid number of chromosomes. |
Gametes | Cells that are haploid. Gametes combine in fertilization to form a zygote. Also known as sperm and egg cells. |
Fertilization | The combination of haploid gametes to form a diploid zygote. |
Meiosis | The process by which chromosome number is cut in half. Diploid cells become haploid by the process of meiosis. Gametes are produced. |
Budding | A form of asexual reproduction in which an identical copy of an organism "buds" from some part of the parent structure. |
Binary Fission | A form of asexual reproduction in which a single cell divides to become two. |
Regeneration | A form of asexual reproduction in which an organism can re-create missing parts. Some creatures, like sea stars, can be cut into many pieces capable of growing into complete new stars. |
Centrosome | Organelle closely associated with the nucleus. Contains centrioles. Only found in animal cells. |
Centrioles | Produce spindle during mitosis. |
Centromere | The center point of chromosome X's seen during metaphase of mitosis. Chromosomes attach to spindle at the centromere. |
Zygote | A fertilized egg |
Haploid | Containing one half the full complement of DNA |
Diploid | Containing the full complement of DNA. Two forms for each gene. Homologous pairs. |
Independent Assortment (Independent Orientation) | During anaphase I, chromosomes split to opposite ends of the cell independent of each other. The number of possible assortments is given by 2 to the "n" power, where "n" is the number of chromosomes. Gives rise to genetic variation in gametes. |
Crossing Over | During prophase I, DNA is shared between replicated chromosomes. This gives rise to genetic variation in gametes. |