Cell cycle, meiosis, mitosis

• What are stem cells?

  Unspecialized cells that can differentiate
• What happens to cells as an organism develops?

  Cells differentiate to form specialized types
• Name three types of specialized cells.

  Sperm, nerve, and muscle cells
• What does totipotent mean?

  Can become any type of cell
• What are multipotent cells?

  Cells with limited potential to differentiate
• What are pluripotent cells capable of?

  Developing into most but not all cell types
• What does haploid mean?

  One complete set of chromosomes
• What does diploid mean?

  Two sets of chromosomes
• What are homologous chromosomes?

  A pair of chromosomes with the same genes
• What are somatic cells?

  Body cells
• What are gametes?

  Mature haploid male or female germ cells
• What is a gene?

  A segment of DNA coding for a polypeptide
• What is a locus?

  Location of a gene on a chromosome
• What is the cell cycle?

  A series of events for cell growth and division
• What occurs during the G1 phase?

  Cells grow and perform normal functions
• What happens during the S phase?

  DNA is replicated
• What occurs during the G2 phase?

  Cell duplicates its organelles
• What are cell cycle checkpoints?

  Mechanisms that monitor cell cycle preparedness
• What are alleles?

  Different forms of the same gene
• What are sister chromatids?

  Identical copies of a chromosome
• What is a centromere?

  Area where chromatids are attached
• What is a bivalence?

  A pair of homologous chromosomes
• What is mitosis?

  Cell division producing identical daughter cells
• What are the stages of mitosis?

  Prophase, metaphase, anaphase, telophase
• What happens during prophase?

  Chromosomes condense and become visible
• What occurs during metaphase?

  Chromosomes line up at the cell's equator
• What happens during anaphase?

  Sister chromatids separate to opposite ends
• What occurs during telophase?

  Chromosomes unwind and nuclear envelope reforms
• What is cytokinesis?

  Division of the cytoplasm
• What is meiosis?

  Nuclear division producing genetically different gametes
• How many nuclear divisions occur in meiosis?

  Two nuclear divisions
• Where does meiosis occur?

  In the testes and ovaries
• What is variation in meiosis achieved by?

  Crossing over and independent assortment
• What is fertilization?

  Fusion of two haploid gametes
• What happens during meiosis I?

  Homologous chromosomes separate
• What happens during meiosis II?

  Sister chromatids separate
• What is crossing over?

  Exchange of portions of chromatids during meiosis
• What occurs during prophase I?

  Crossing over and chromosomes become visible
• What happens during metaphase I?

  Homologous chromosomes line up at the cell's center
• What occurs during anaphase I?

  Homologous chromosomes separate