1. Define haploid cell
    • Cell containing only 1 set of chromosomes
    • ie gametes
  2. Define diploid cell
    • Cell containing two sets of chromosomes
    • ie somatic cells
  3. Define aneuploidy
    • Incorrect number of a specific chromosome in a cell. Can affect multiple chromosomes
    • ie Down syndrome
  4. Define a monosomic cell
    Cell resulting from a gamete without a specific chromosome. Resulting cell has only one of a specific chromosome
  5. Define trisomic cell
    • Cell with 3 of a certain chromosome. 
    • i.e Down syndrome
  6. Define nondisjunction
    • Where homologous chromosomes fail to separate during meiosis I OR
    • Sister chromatids fail to separate during meiosis II resulting in aneuploid gametes
  7. What is Klinefelter syndrome? Symptoms?
    • Where somatic cells contain an extra X chromosome - XXY.
    • Males who are taller, feminine, sterile, may see breast development
  8. What is Turner syndrome? Symptoms?
    • Where somatic cells contain only an X chromosome - XO.
    • Females who are shorter, sterile, may exhibit brown spots on skin
  9. What is a Barr body? How does it arise?
    Barr body is a region of hetero-chromatin close to the nuclear envelope found in females following X inactivation.
  10. List n, number of cells and number of chromosomes at each step of meiosis.
    • Prophase I - 2n=46, duplicated, 1 diploid cell
    • Telophase I - n=23, duplicated, 2 haploid cells
    • Telophase II n=23, unduplicated, 4 haploid cells
  11. Define deletion.
    Removal/loss of a chromosomal segment
  12. Define Duplication.
    Repeat of a chromosomal segment on a chromosome
  13. Define Inversion.
    Reversal of a chromosomal segment on a chromosome
  14. Define Translocation.
    Segment transferred from one chromosome to another.
  15. Define reciprocal translocation.
    Exchange of chromosomal segments between two chromosomes
  16. Define polyploidy.
    • Possession of multiple ENTIRE sets of of chromosomes.
    • i.e a tetraploid has 4 sets of chromosomes
  17. Define incomplete dominance.
    • Where both alleles in a heterozygous sample are shown in phenotype AT REDUCED LEVELS
    • ie Snap dragon flower shows reduced red pigment in RW heterozygote
  18. Define Co-dominance.
    Where phenotypes of both alleles are seen in a heterozygous sample
  19. Define Epistasis.
    • Gene at one locus affects another. 
    • i.e Labradors can have black or brown hair pigment - only if gene for hair pigment is present at another locus
  20. Define Polymorphism.
    • Where there are multiple alleles for a gene.
    • i.e eye colour - blue, brown, green - however, each human only has two alleles.
  21. Define Pleiotropy.
    • Ability of a gene to have multiple effects
    • i.e sickle cell anemia
  22. Describe how environmental factors can contribute to variation in ratios predicted by Mendelian genetics.
    • Environment can cause phenotypic variation in individuals with same genotype
    • i.e, hydrangea flowers with same genotype are different colours depending on soil pH
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