Genetics and Inheritance

1. Genetics and Inheritance How do you relate these two terms?

2. Genetics • Is the study of heredity or the passing of traits from one generation to the next.

3. Homozygoussame 1. Assign a letter to a trait. TRAITLETTER Flower color R 2. Pink is the dominant color so use a big R 3. White is the recessive color so use a small r. 4. RR = HOMOZYGOUS DOMINANT (you see the dominant color)5. rr = HOMOZYGOUS RECESSIVE (you see the recessive color)

4. What is Dominant(R) vs. Recessive(r)? Dominant (R) – only one of the genes needs to be present for it to be expressed (become the phenotype). ONLY rr = RR = Rr = Recessive (r) – both genes must be present in order for this version of the gene to be expressed.

5. Heterozygous = different 1. Rr = HETEROZYGOUS DOMINANT 2. RR = ? 3. rr = ? 4. Can we have HETEROZYGOUS RECESSIVE??

6. Answer these questions If the trait HEIGHT has the dominant gene of TALL and the recessive gene of SHORT. What genotypes would you assign the following people (hint: one is not possible)? 1. Bart is heterozygous Tall. 2. Midge is homozygous Tall. 3. Homer is homozygous Short. 4. Lucy is heterozygous Short. 1. Hh 4. NOT POSSIBLE ;o) 2. HH 3. hh

7. THIS IS A PUNNETT SQUARE FOR A • HETEROZYGOUS DOMINANT (Rr) AND A Punnett Square r R 2. HOMOZYGOUSRECESSIVE (rr) CROSS. r r HOW DO YOU THINK WE SHOULD FILL IN THE SQUARES?

8. SET UP THE FOLLOWING PUNNET SQUARE • Heterozygous Dominant crossed with Homozygous Recessive. 2. What is the percentage of Dominant and recessive phenotypes (what you see)?

9. Dihybrid Cross • A cross involving parents that differ in two pairs of traits.

10. Co-dominance • Condition where BOTH alleles for a trait in an individual are expressed (PHENOTYPE). THE DOMINANT ALLELE IS RED THE RECESSIVE ALLELE IS WHITE THE OFFSPRING WILL SHOW BOTH AND BE RED AND WHITE!

11. Incomplete Dominance A BLEND of two different traits. x = WHITE FLOWER PINK FLOWER RED FLOWER

12. Incomplete Dominance A BLEND of two different traits. Ex. Hazel color eyes x = GREEN EYED DOG HAZEL EYED DOG BROWN EYED DOG

13. ANSWER THESE QUESTIONS Choose one of these answers for each question PLUS tell me if it is a DOMINANT or RECESSIVE phenotype. A.Regular B.CodominanceC.Incomplete Dominance 1. A red flower and a white flower make a red flower. 2. A red flower and a white flower make a white flower. 3. A red flower and a white flower make a red and white flower. 4. A red flower and a white flower make a pink flower.

14. Multiple Alleles • Three or more alleles for the same trait for instance the A,B,O blood groups.

15. Cystic Fibrosis • A recessive genetic disorder caused by the mutation in the gene that codes for a protein responsible for transporting chloride ions.

16. Down Syndrome • An example of a genetic disorder caused by an extra chromosome in pair number 21.

17. A neurological disorder that leads to progressive degeneration of brain cells. Huntington’s Disease is a recessive allele. Right is a pedigree that shows a family passing this trait. Huntington’s Disease • 7. What would be the phenotype and genotype of family member #7? • HH, Huntington’s b. Hh, Huntington’s • c. hh, No Huntington’s d. Hh, No Huntington’s • 8. Which genotype is not possible for family members #11 and #12? • a. HH b. Hh c. hh • d. All of these are possible White = Huntington’s (h) Black = No Huntington’s (H) Half = No Huntington’s (Hh) NUMBER FAMILY MEMBERS AND ASSIGN ALLELE STATUS.