Chromosomes and Cell division

• Cell cycle


  Interphase: G1, G0, S phase, G2 | Mitotic phase: Prophase, Metaphase, Anaphase, Telophase, Cytokinesis
• Checkpoints

  • Regulate the cell cycle | Determine if the cell is ready to divide (no errors likely to happen) | Determine if the internal and external cell environment is "good" for division
• DNA replication


  Unwinding and separation | Reconstruction and elongation | Removal of primers and joining of DNA
• Leading strand


  DNA strand synthesized continuously in the direction of the replication fork
• Lagging strand


  DNA strand synthesized in fragments in the opposite direction of the replication fork
• Telomeres


  Repetitive DNA sequences at the ends of chromosomes
• Telomerase


  Enzyme that lengthens the ends of telomeres
• Haploid


  Having one copy of each chromosome
• Diploid


  Having two copies of each chromosome
• Homologous chromosomes


  Chromosomes carrying the same genes in the same order
• Mitosis


  Prophase | Metaphase | Anaphase | Telophase | Cytokinesis
• Cytokinesis


  The division of the cytoplasm at the end of mitosis/meiosis
• Purpose of mitosis


  • Organism growth/development | Repair (replacement of cells)
• Cancer


  Unregulated cell growth resulting in tumors that spread throughout the body
• Characteristics of cancer cells

  • Lack contact inhibition | Checkpoints do not regulate cell cycle | Divide indefinitely | Lack anchorage dependence
• Proto-oncogenes


  Genes that assist in cell growth and survival
• Oncogenes


  Genes with potential to cause cancer
• Benign tumor


  Abnormal cells that stay localized
• Malignant tumor


  Abnormal cells that move through the body
• Metastasis


  Secondary cancer growth separate from the original tumor
• Meiosis


  Meiosis I: Prophase I, Metaphase I, Anaphase I, Telophase I & Cytokinesis | Meiosis II: Prophase II, Metaphase II, Anaphase II, Telophase II & Cytokinesis
• Sources of genetic variation in meiosis and fertilization

  • Crossing over | Independent assortment | Random fertilization
• Crossing over


  The exchange of gene alleles between homologous chromosomes
• Independent assortment


  Separation of homologous chromosomes (maternal and paternal) is random
• Oogenesis


  The process of producing egg cells in females
• Spermatogenesis


  The process of producing sperm cells in males
• Gametes


  Reproductive cells (sperm and egg)
• Internal fertilization


  Fertilization that occurs within the body
• External fertilization


  Fertilization that occurs outside the body
• Pollination


  The transfer of pollen from the anther of a plant to the stigma of a plant
• In vitro fertilization


  Fertilization of eggs by sperm in a laboratory setting
• Asexual reproduction


  The production of genetically identical offspring by a single parent
• Nondisjunction


  Failure of chromosomes to separate during cell division, leading to aneuploidy
• Aneuploidy


  An abnormal number of chromosomes
• Monosomy


  The absence of one member of a pair of chromosomes
• Trisomy


  The presence of an extra copy of a chromosome
• Amniocentesis


  A diagnostic test for prenatal diagnosis of chromosomal abnormalities
• Chorionic Villus Sampling (CVS)


  A diagnostic test for prenatal diagnosis of chromosomal abnormalities