Genetics

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Genetics
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Heredity passing of traits from parents to
offspring.

• Genetics science of heredity
• Mendel 1860 studied cross-pollination.
  Conclusions
• 1. heredity traits are passed during
  reproduction.
• 2. each trait has two gene factors, one from
  mother one from father

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• 3. the two factors may be alike (purebred)
  or unalike (hybrid).
• 4. In hybrid, gene that is seen is
  dominant, gene hidden is recessive.
• Heredity Gene Factor
• Mitosis Cell Division all regular cells go
  through this type of division. Chromosomes
  replicate.
• 46 chromosomes? 46/46 (2 cells)

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• Meiosis Cell division that makes reproductive
  cells contain ½ the chromosomes of regular cell.
• 46 ? 23/23/23/23 (4 cells)
• F. DNA Makes up genes deoxyribonucleic acid.
  Has nucleotides Adenine, Thymine, Cytosine,
  Guanine

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Punnett Square for flower color in pea plants

• P(purple) p(white)
• P PP Pp
• p Pp pp

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Other Genetic Patterns

1. Incomplete Dominance Neither trait is dominant
   and two forms of a trait combine (blend).
   Example red white flowers ? pink flowers
2. Codominance two forms of a trait show at the
   same time without blending. Example black
   chicken white chicken ? chickens with some
   black some white feathers

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• Sex Chromosome X Y chromosome. X female Y
  male
• 1. Sex-linked Trait carried on the X
  chromosome only
• a. gene for hemophilia
• h (H normal gene)

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Punnett Square

• XH Y
• XH XHXH XHY
• Xh XHXh XhY ? hemophiliac

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• b. Color Blindness sex linked
• Genetic Diseases in offspring who is purebred
  for the recessive problem gene.
• 1) Tay Sachs cant break down fat
• 2) Sickle Cell Anemia red blood cells cant
  carry oxygen.

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Parents 1 2 are carriers but have normal
phenotype

• T t
• T TT Tt
• t Tt tt ? tay sachs
  (recessive)