Gender

• Chromosomes


  Contain the genes which determine inherited characteristics
• Human chromosomes


  • 23 pairs
  • 22 pairs contain genes for inherited characteristics
  • 1 pair determines sex
• Sex chromosomes


  X and Y chromosomes
• Male sex chromosomes


  • X and Y
• Female sex chromosomes


  • X and X
• Inheritance of sex


  1. Woman's gametes have X chromosome

  2. Man's gametes have X or Y chromosome

  3. Offspring have XX (female) or XY (male)
• On average, 50% of offspring are female and 50% are male
• The sex ratio of 1:1 is just a probability, in reality a couple may have all male or all female offspring