Mitosis and Meiosis
Cell Cycle | a series of events that cells go through as they grow and divide. a cell grows, prepares for division, and divides to form two daughter cells, each of which then begins the cycle again |
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Interphase | phase of the cell cycle in which a typical cell spends most of its life. Interphase is the 'daily living' or metabolic phase of the cell, in which the cell obtains nutrients and metabolizes them, grows, replicates its DNA in preparation for mitosis, and conducts other "normal" cell functions |
S phase | stands for synthesis, DNA replication. To make DNA easier to move & replicate, the cell packages the DNA into chromosomes |
G1 phase | cells receive a signal and enter into a stage of growth. They also prepare to have their DNA replicated |
G2 phase | Preparation for Mitosis, growth |
Mitosis | The stage of the cell cycle where the cell divides. Starts with one diploid cell (two sets of chromosomes) (2n) and ends with two diploid cells (2n). Growth, development, and repair |
Homologous Chromosomes | Look alike and carry genes for the same trait. Same size, same shape, same organization |
Centromere | structure in a chromosome that holds together the two chromatids |
Asexual reproduction | involves one parent and produces offspring that are genetically identical to each other and to the parent. a mode of reproduction in which a new offspring is produced by a single parent |
Prophase | Chromosomes become visible. Spindle fibers appear. Nuclear membrane (envelope) disappears |
Metaphase | Spindle fibers have attached to all the chromosomes. Chromosomes line up in the middle of the cell (metaphase plate). Meta- “Middle”. Before proceeding there is a checkpoint to make sure all chromosomes are lined up correctly |
Anaphase | Sister chromosomes are separated and pulled to opposite ends of the cell. Microtubules push the cell apart, making it longer |
Telophase | Mitotic spindle disappears. Two new nuclei form. The chromosomes start to “decondense” |
Cytokinesis | Division of the cytoplasm. Overlaps with the final stages of replication (anaphase and telophase) |
Tumor | a disease caused when cells divide uncontrollably and spread into surrounding tissues. |
Tumor suppressor gene | normal genes that slow down cell division or tell cells to die at the right time (a process known as apoptosis or programmed cell death). When these genes don't work properly, cells can grow out of control, which can lead to cancer |
Proto-oncogene | a group of genes that cause normal cells to become cancerous when they are mutated |
G0 phase | Resting state- cell is outside of the cycle. Neurons are in a permanent state of this phase |
Sexual reproduction | the production of new organisms by the combination of genetic information of two individuals of different sexes. an organism combines the genetic information from each of its parents and is genetically unique |
Gametes | a reproductive cell of an animal or plant. sperm and egg cells |
Meiosis | The process of making sperm and egg cells. a type of cell division that reduces the number of chromosomes in the parent cell by half and produces four gamete cells. This process is required to produce egg and sperm cells for sexual reproduction. |
Fertilization | the union of two gametes, the process in which a new cell is formed when two gametes (sex cells) –sperm and ova fuse together |
Crossing over | the exchange of DNA between paired homologous chromosomes (one from each parent) that occurs during the development of egg and sperm cells (meiosis), Exchange of DNA between homologous chromosomes (one from each parent) |
Somatic cells | all the nonreproductive cells in an organism, tissue cells, nerve cells, and blood cells |
Binary Fission | How bacteria cells divide and reproduce. A form of asexual reproduction. Stages: Parent cell-> DNA duplicates-> Cytoplasm divides-> 2 daughter cells are formed |