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Student Impact!

Student Impact!. High Fives: What did you like about the genetics unit? What would you like to do again? Anything that you would like me to know 

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Student Impact!

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  1. Student Impact! • High Fives: What did you like about the genetics unit? What would you like to do again? Anything that you would like me to know  • Nudges For Next Time: What would you change? What didn’t you like? What would you suggest we do in the next unit? Any other things you want to mention 

  2. INCOMPLETE DOMINANCE, CODOMINANCE, MULTIPLE ALLELES, POLYGENIC TRAITS BEYOND DOMINANT & RECESSIVE ALLELES

  3. DOMINANT? RECESSIVE? NEITHER? • NOT ALL GENES SHOW SIMPLE PATTERNS OF DOMINANT AND RECESSIVE ALLELES. IN MOST ORGANISMS, GENETICS IS MORE COMPLICATED, BECAUSE THE MAJORITY OF GENES HAVE MORE THAN TWO ALLELES. MANY IMPORTANT TRAITS ARE CONTROLLED BY MORE THAN ONE GENE.

  4. INCOMPLETE DOMINANCE • PAIRS OF ALLELES PRODUCE A HETEROZYGOUS PHENOTYPE THAT RESULTS IN AN APPEARANCE IN BETWEEN THE PHENOTYPES OF THE TWO PARENTAL VARIETIES. • EXAMPLE: SNAPDRAGON COLOR

  5. INCOMPLETE DOMINANCE • With incomplete dominance, a cross between organisms with two different phenotypes produces offspring with a third phenotype that is a blending of the parental traits. 

  6. INCOMPLETE DOMINANCE - SNAPDRAGONS

  7. INCOMPLETE DOMINANCE – Humans • HYPERCHOLESTEROLEMIA – DANGEROUSLY HIGH LEVELS OF CHOLESTEROL IN THE BLOOD • NORMAL INDIVIDUALS ARE HH • HETEROZYGOTES ARE Hh (1 IN 500) • HOMOZYGOUS INDIVIDUALS WITH hh (1 IN 1,000,000) 5X NORMAL CHOLESTEROL LEVEL

  8. INCOMPLETE DOMINANCE PROBLEMS • YELLOW GUINEA PIGS CROSSED WITH WHITE GUINEA PIGS ALWAYS PRODUCE CREAM COLORED GUINEA PIGS. • A. COMPLETE THE PUNNETT SQUARE FOR THE CROSS BETWEEN A WHITE GUINEA PIG AND A YELLOW GUINEA PIG. • B. COMPLETE THE PUNNETT SQUARE FOR THE CROSS BETWEEN TWO CREAM-COLORED GUINEA PIGS. • C. GIVE THE PHENOTYPIC AND GENOTYPIC RATIO FOR THE OFFSPRING IN A AND B.

  9. CODOMINANCE • BOTH ALLELES CONTRIBUTE TO THE PHENOTYPE OF THE ORGANISM • EXAMPLE: IN HORSES, THE ALLELE FOR RED HAIR IS CODOMINANT WITH THE ALLELE FOR WHITE HAIR. HORSES WITH BOTH ALLELES ARE ROAN BECAUSE THEIR COATS ARE A MIXTURE OF BOTH RED AND WHITE HAIRS

  10. CODOMINANCE • With codominance, a cross between organisms with two different phenotypes produces offspring with a third phenotype in which both of the parental traits appear together. 

  11. CODOMINANCE PROBLEMS • 1. WHEN A RED BULL IS BRED TO A WHITE COW, THE COLOR OF THE CALF IS ROAN. • A. COMPLETE THE PUNNETT SQUARE FOR THE CROSS BETWEEN A RED BULL AND A WHITE COW • B. GIVE THE GENOTYPIC RATIO AND PHENOTYPIC RATIO OF THE OFFSPRING. • C. A ROAN BULL AND A ROAN COW ARE BRED. GIVE THE GENOTYPIC RATIO AND PHENOTYPIC RATIO OF THIS CROSS.

  12. What type of inheritance are each of these examples? CODOMINANCE Incomplete Dominance

  13. MULTIPLE ALLELES • MORE THAN TWO POSSIBLE ALLELES EXIST IN A POPULATION • EX. COAT COLOR IN RABBITS – DETERMINED BY A SINGLE GENE WITH AT LEAST 4 DIFFERENT ALLELES THAT CAN PRODUCE 4 POSSIBLE COAT COLORS • EX. HUMAN GENE FOR EYE COLOR

  14. Multiple Alleles

  15. MULTIPLE ALLELES • HUMAN BLOOD TYPES – CHROMOSOME 9 • ONE GENE, THREE ALLELES, PRODUCE 4 PHENOTYPES • A PERSON’S BLOOD GROUP MAY BE O, A, B OR AB • THESE LETTERS REFER TO 2 CARBOHYDRATES THAT MAY BE FOUND ON THE SURFACE OF RED BLOOD CELLS (RBC)

  16. ABO BLOOD GROUPS

  17. Blood Types: What do they look like?

  18. ABO BLOOD GROUPS

  19. ABO BLOOD GROUP PROBLEMS • COMPLETE A PUNNETT SQUARE FOR: • HOMOZYGOUS TYPE A x TYPE O • HETEROZYGOUS TYPE A x TYPE O • HOMOZYGOUS TYPE A x HOMOZYGOUS TYPE B • HETEROZYGOUS TYPE B x HOMOZYGOUS TYPE A • HETEROZYGOUS TYPE A x HETEROZYGOUS TYPE B • HETROZYGOUS TYPE B x TYPE O

  20. Practice problems • A TYPE AB MALE MARRIES A TYPE O FEMALE. • WHAT ARE THEIR GENOTYPES? • COMPLETE A PUNNETT SQUARE TO SHOW THE POSSIBLE GENOTYPES OF THEIR CHILDREN.

  21. Practice problems • A TYPE A MALE MARRIES A TYPE B FEMALE. THEY HAVE TWO CHILDREN. ONE CHILD IS TYPE AB AND THE OTHER CHILD IS TYPE O. • WHAT ARE THE GENOTYPES OF THE PARENTS? • COMPLETE A PUNNETT SQUARE TO SHOW THE GENOTYPES OF THESE TWO CHILDREN AND FOR ANY FUTURE CHILDREN.

  22. Practice problems • A TYPE A MALE IS MARIED TO A TYPE O FEMALE. USING PUNNETT SQUARES, EXPLAIN HOW IT WOULD BE POSSIBLE FOR THEM TO HAVE A: • TYPE A CHILD. • TYPE B CHILD. • TYPE O CHILD.

  23. Practice problems • A TYPE AB MALE MARRIES A TYPE B FEMALE. USING PUNNETT SQUARES, EXPLAIN HOW IT WOULD BE POSSIBLE FOR THEM TO HAVE A: • TYPE AB CHILD • TYPE A CHILD • TYPE O CHILD • TYPE B CHILD

  24. Practice problems • A TYPE AB MALE MARRIES A TYPE AB FEMALE. USING PUNNETT SQUARES, EXPLAIN HOW IT WOULD BE POSSIBLE FOR THEM TO HAVE A: • TYPE AB CHILD • TYPE A CHILD • TYPE B CHILD • TYPE O CHILD

  25. Practice problems • A TYPE O MALE MARRIES A TYPE O FEMALE. • WHAT ARE THE POSSIBLE GENOTYPES OF THEIR CHILDREN?

  26. Practice problems • A TYPE A MALE, WHOSE FATHER IS TYPE O, MARRIES A TYPE O FEMALE. WHAT ARE THE POSSIBLE GENOTYPES OF THEIR CHILDREN? • THE MALE FROM THE PREVIOUS PROBLEM HAS A BROTHER WHO IS TYPE B. WHAT IS THEIR MOTHER’S BLOOD TYPE? • THE BROTHERS IN THE ABOVE PROBLEMS HAVE A SISTER WHOSE BLOOD TYPE IS O. IS THIS POSSIBLE?

  27. POLYGENIC TRAITS • TRAITS CONTROLLED BY TWO OR MORE GENES • EX. 3 GENES INVOLVED MAKING THE REDDISH-BROWN PIGMENT IN THE EYES OF FRUIT FLIES • EX. WIDE RANGE OF HUMAN SKIN COLOR DUE TO MORE THAN 4 DIFFERENT GENES CONTROLLING THE TRAIT

  28. POLYGENIC TRAIT – COAT COLOR IN MICE

  29. POLYGENIC TRAIT VIDEO Polygenic Traits

  30. SEX-LINKED TRAITS • IN HUMANS, SEX IS DETERMINED BY THE 23RD PAIR OF CHROMOSOMES – THE SEX CHROMOSOMES! • THE SEX CHROMOSOMES ARE THE X AND THE Y CHROMOSOMES • XX – FEMALE • XY – MALE

  31. SEX-LINKED TRAITS • MOST SEX-LINKED GENES ARE X-LINKED GENES. • WHY? THE X CHROMOSOMES ARE LONGER AND CONTAINS THOUSANDS MORE GENES THAN THE Y CHROMOSOME. • X CHROMOSOME CONTAINS 1098 GENES. • Y CHROMOSOME CONTAINS 26 GENES.

  32. KARYOTYPE

  33. SEX-LINKED TRAITS • FOR EACH GENE EXCLUSIVELY ON THE X CHROMOSOME, THERE ARE TWO ALLELES OF EACH GENE • MALES, XY, HAVE ONLY ONE ALLELE • A MALE, XY, WITH A RECESSIVE ALLELE ON THE X CHROMOSOME, WILL ALWAYS EXHIBIT THAT RECESSIVE TRAIT BECAUSE THERE IS NO CORRESPONDING ALLELE ON THE Y CHROMOSOME.

  34. EXAMPLES OF SEX-LINKED TRAITS • IN HUMANS: • Red-Green Color Blindness • Hemophilia • Duchenne Muscular Dystrophy • IN CATS • Calico coat color • IN FRUIT FLIES: • Eye Color

  35. WORKING PUNNETT SQUARES • IDENTIFY EACH INDIVIDUAL AS MALE OR FEMALE ACCORDING TO THEIR SEX CHROMOSOMES • EX. XX or XY • THE LETTERS REPRESENTING THE TRAIT ARE PLACED AS SUPERSCRIPTS ABOVE THE X CHROMOSOME • EXAMPLE: XR or Xr

  36. EYE COLOR IN FRUIT FLIES • THE GENE FOR EYE COLOR IS ON THE X CHROMOSOME. • THE ALLELE FOR RED EYES IS DOMINANT OVER WHITE EYES • PROBLEM: • IF A WHITE-EYED FEMALE FRUIT FLY IS MATED WITH A RED-EYED MALE, PREDICT THE POSSIBLE OFFSPRING

  37. SEX-LINKED TRAITS VIDEO SEX-LINKED TRAITS VIDEO

  38. COAT COLOR IN CATS • Coat color in cats is an X-linked gene, with alleles for black and orange-brown • XBXB and XBY cats will have a black coat • XOXO and XOY will have an orange-brown coat • female cats with XBXO are Calico!!

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