2.1 Nuclear Matters

• DNA


  Deoxyribonucleic acid
• Location of DNA in a human cell

  Cell nucleus
• Cells in the body that are not sex cells

  Somatic cells
• Double set of genetic instructions

  Genotype (chromosomes in pairs)
• Chromosomes are stained with dyes as they may be more difficult to see without it and the contrast helps details become distinguishable
• Chromosomes are not always visible in a cell, they are only visible when the cell is about to divide as the DNA is compacted, when not dividing the DNA is spread throughout the cell
• A human somatic cell should expect to find 46 chromosomes
• Gametes have half the number of chromosomes (23)
• Ovum


  Female gamete
• Sperm


  Male gamete
• Chromosome


  Genetic material organised into structures
• Sex chromosomes


  Determine an individual's sex and sexual dimorphism
• Autosomes


  Chromosomes not directly involved in determining sex
• Somatic cells


  Cells found in the body except for gametes, have 46 chromosomes, diploid
• Sex cells (gametes)


  Haploid, have half the number of chromosomes (23)
• Mitosis


  Cell division for somatic cells
• Meiosis


  Cell division for gametes
• Homologous chromosomes


  Matching pairs of chromosomes
• Non-homologous chromosomes


  Chromosomes that do not match
• Gene


  Unit of genetic material
• DNA


  Genetic material that genes are made of
• Staining


  The process of applying a dye to enhance the visibility of chromosomes.