Skip to main content
Back

anatomy lecture 4

Control buttons has been changed to "navigation" mode.
1/28

Terms in this set (28)

  • What is the chromosome composition after DNA replication in G2 phase?
    46 chromosomes, each with 2 sister chromatids, totaling 92 chromatids.
  • What occurs during the G2 phase of the cell cycle?
    Growth and metabolism with production of enzymes and proteins needed for cell division; centrosome replication completes.
  • What are the four phases of mitosis in order?
    Prophase, Metaphase, Anaphase, Telophase (PMAT).
  • What happens during prophase of mitosis?
    Chromosomes condense and become visible; centrosomes move to opposite poles; spindle microtubules attach to kinetochores.
  • Describe the metaphase stage of mitosis.
    Chromosomes line up single file along the cell equator, organized by the spindle apparatus.
  • What key event occurs during anaphase of mitosis?
    Sister chromatids separate as spindle microtubules shorten, pulling chromatids to opposite poles; cytokinesis begins.
  • What occurs during telophase of mitosis?
    Chromosomes uncoil into chromatin; nuclear envelope and nucleoli reappear; spindle disassembles; cytokinesis completes.
  • What is cytokinesis?
    Division of the cytoplasm that usually begins in anaphase and completes after telophase.
  • What is the result of mitosis and cytokinesis?
    Two diploid daughter cells identical to the original cell.
  • What is the purpose of meiosis?
    To produce haploid gametes (sperm and ova) with genetic variation.
  • How many genetically unique gametes are produced from one cell by meiosis?
    Four genetically unique gametes.
  • What happens during prophase I of meiosis that differs from mitosis?
    Homologous chromosomes pair to form tetrads, allowing crossing over and genetic recombination.
  • Describe metaphase I of meiosis.
    23 tetrads line up along the cell equator.
  • What occurs during anaphase I of meiosis?
    Homologous chromosomes separate and move to opposite poles; sister chromatids remain attached.
  • How does meiosis II differ from mitosis?
    It starts with haploid cells (23 chromosomes) and separates sister chromatids like mitosis.
  • What is the chromosome number change during meiosis I?
    From diploid (2n) to haploid (n).
  • What is a zygote?
    A diploid (2n) cell formed by the fusion of haploid sperm and egg.
  • What are the stages of the pre-embryonic period?
    Fertilization, cleavage divisions forming morula, blastocyst formation, and implantation.
  • What is a morula?
    A solid ball of 16-32 cells formed about 72 hours after fertilization, same size as the zygote.
  • What are the main parts of the blastocyst?
    Blastocoel (fluid cavity), embryoblast (inner cell mass), and trophoblast (outer layer forming chorion).
  • What is the role of the trophoblast?
    Forms the chorion, which provides nutrients to the developing embryo and contributes to placenta formation.
  • What are the two layers of the bilaminar embryonic disc?
    Epiblast (upper layer) and hypoblast (lower layer).
  • What germ layers form from the epiblast?
    Ectoderm, mesoderm, and endoderm.
  • What does the ectoderm form?
    Nervous system and epidermis of the skin.
  • What does the mesoderm form?
    Muscles, cardiovascular system, dermis, and most bones.
  • What does the endoderm form?
    Epithelial lining of digestive, respiratory, urinary, and reproductive systems and their glands.
  • What is the chorion and its function?
    An extraembryonic membrane derived from trophoblast cells; forms chorionic villi for nutrient and gas exchange in the placenta.
  • What occurs during the fetal period?
    Growth and maturation of organs from the 9th week to birth (around 40 weeks).