Topic 4&10 - Genetics

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Topic 4&10 - Genetics
2013-10-24 15:20:33
IB DP BIO Genetics core HL

IB DP BIO Genetics (core) and AHL
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  1. CORE: What is the order of cell division (in mitosis)
    • Interphase - Prophase - Metaphase - Anaphase - Telophase
    • OR can be remembered by...
    • I Picked My A** Today
  2. CORE: Explain the consequence of a base substitution when thinking about sickle-cell anemia.
    GAG (glutamic acid) is changed (mutated) to GTG (valine)

    The change in ONE base substitution means that another amino acid is made, which then completely stuffs up the protein and makes it fold badly.
  3. CORE:What is a reduction division?
    Where the genetic information is reduced by half (i.e. meiosis)
  4. AHL: What is Mendel’s Law of Segregation
    The characteristics of a diploid organisms are determined by alleles which occur in pairs. Of a pair of such alleles, only one can be carried in a single gamete.
  5. CORE: What is Monohybrid inheritance
    Inheritance of 1 trait. 2 alleles – one from either parent.
  6. CORE: What method/process can be used to amplify a small amount of DNA (maybe taken from a crime scene)?
    PCR = polymerase chain reaction
  7. CORE: How can you separate DNA fragments once they have been cut up?
    • Gel electrophoresis
  8. CORE: What is this an example of? Sometimes there are 3 or more alleles for the same gene.
    Multiple alleles
  9. AHL: What is this?
    A characteristic that is influenced by more than one gene.
    Polygenic inheritance
  10. AHL: What kind of variation (continuous or discontinous) do you have with polygenic inheritance?

    Most examples of polygenic inheritance involve more than two genes with codominant alleles. As number of genes increases the number of possible phenotypes increases. The variation in the population is continuous and not discontinous (or discrete).
  11. AHL: Give 2 examples of polygenic inheritance
    • Skin colour
    • Grain colour in wheat
  12. AHL: Give 2 examples of polygenic inheritance
    Each of a pair of alleles for a particular gene can combine randomly with either of another pair of alleles for a different gene.
  13. AHL: What is this?
    Where 2 traits are equally dominant and both are expressed.
  14. AHL: What gene determines sex?
    SRY gene (sex related Y gene)
  15. AHL: How does SRY determine sex?
    • SRY codes for a protein – testis determining factor.
    • This switches on other genes causing embryo to devleop male features.
    • SRY gene supresses female structures by activating a gene on chromosome 19.
    • This gene produces protein Mullerian-inhibiting substance which destroys female structures.
  16. AHL: What is inheritance of 2 traits?
    Dihybrid inheritance
  17. AHL: If genes are UNLINKED...what does that mean?
    They are on different chromosomes.
  18. AHL: If you get strange ratios when doing dihybrid crosses (i.e. not 1:1:1:1 or 9:3:3:1) what can you assume?
    They are LINKED (on same chromosome)
  19. AHL: What is gene linkage?
    • This means two genes are on the same chromosome. They tend to be inherited together…because they are linked.
    • They do not follow law of independent assortment. They do not produce the 9:3:3:1 ratio when heterozygous parents are crossed (as they do in unlinked genes).
  20. AHL: What can you say if you know that the genes are close together on a chromosome?
    That they are more likely to be inherited together. The further apart they are, the more likely they are to have a chiasmata (crossing over between them)
  21. CORE: What is a karyotype?
    • The number and appearance of the chromosomes in an organism is the karyotype.
  22. CORE: How and when can you make a karyotype?
    Cells are grown, and then stopped in metaphase of mitosis and an image taken. Chromosomes are ‘cut out’ and ordered by size. Sex chromosomes last. Cells can be examined for any abnormalities. Cells can be taken by Amniocentesis (week 15-16) or Chorionic villus sampling (week 8-12)
  23. CORE: What is a test cross (sometimes called a back cross)?
    Always cross with a homozygous recessive individual (for either one trait if in monohybrid, or in both traits if in dihybrid inheritance).
  24. CORE: What is sex linkage?
    When a gene is carried on the sex chromosomes. Pattern of inheritance is different for males and females.
  25. CORE: What causes sickle cell anemia?
    • A single base mutation
    • On Chromosome 11
    • GAG (at 6th amino acid position) is changed to GTG
  26. CORE: What are the genetics of sickle cell anemia?
    • Problem occurs on Chromosome 11
    • GAG (at 6th amino acid position) is changed to GTG
    • GAG gives negatively charged Glutamic acid
    • GTG (the mutation) gives a neutral charged Valine
    • This gives the allele HbS
    • This produces the sickle shaped red blood cells
  27. CORE: What is the amino acid change in sickle cell anemia?
    • Glutamic acid GAG (normal) to¬†Valine GUG (mutation)
    • GREAT ACID to Very Awful
  28. What are eukaryote chromosomes made from?
    DNA and proteins.
  29. CORE: What are the stages of the cell cycle?
    • Interphase
    • 1.G1
    • 2. S
    • 3. G2
    • Mitosis and cytokinesis
    • Prophase
    • Metaphase
    • Anaphase
    • Telophase
  30. CORE: What happens in S phase of the cell cycle?
    Period during which the DNA in the nucleus is replicated (Synthesis)
  31. CORE: What happens in G2 of the cell cycle?
    A period when the cell prepares for division.
  32. CORE: Which pair represents homologous chromosomes?
    Pair 4 and 6
  33. CORE: What kind of diagram/chart is this?
    Pedigree chart
  34. CORE: Give 2 examples of sex linked traits
    Hemophilia and color blindness
  35. CORE: Which enzymes are needed to produce recombinant plasmids to be used in gene transfer?
    Restriction enzymes to cut

    and DNA ligase to glue the DNA back together.
  36. CORE: What happens in G1 of the cell cycle?
    Growth of organelles and cytoplasm.