CH 22 - Developmental Genetics & Immunogenetics - Reading notes

  • 22.1 : Development Takes Place Through Cell Determination

    • Multicellular organism begins as unicellular fertilized egg, which undergoes repeated cell divisions

    • Totipotent - The potential to develop into any cell type

      • each cell in early development is totipotent

    • A cell becomes committed via a process called determination - process by which a cell becomes committed to developing into a particular cell type

  • Antibody production - lect notes

    • lymphocytes (white blood cells) involved in immune response

    • Small lymphocytes include B and T cells

    • B cells devleop in bone marrow, when activated by antigen (foreign protein on virus/bacteria) they form plasma cells that make antibodies after a few days

    • Antibodies attach to antigens, mount the body’s defense system

    • We develop immunity over time from clonal selection — cells with antibodies to an antigen are stimulated to proliferate and make more antibodies

      • each antibody binds to a specific antigen

    • Antibodies are proteins called immunoglobins, with 2 identical (L) light chains and 2 identical heavy (H) chains

      • Disulfide bonds (-S-S-) holds chains together

      • Two arms of Y-shaped antibody have antigen-binding sites, stimulate clonal selection

    • Antibody classes & Domains

      • IgG most abundant class in blood, IgM recognizes new antigens

      • Each polypeptide chain in an antibody is organized into domains of 110 amino acids each

      • H chains have 4 domains (3 constant regions, 1 variable region) L chains have 2 domains (1 constant, 1 variable)

    • Somatic recombination - random DNA rearrangements during B cell development that join different gene segments and exclude others

  • Heavy-Chain recombination

    • xx

  • Sex Determination in Mammals

    • Genes on Y chromosome (SRY) code for testis-determining factor (TDF), which causes testis formation