1. Gene Interaction Review Unit 8B

2. What is the difference between a genotype and a phenotype? Genotype is the alleles that are paired. Phenotype is the physical trait that is expressed. Example: Aa would be a genotype while free earlobes would be a phenotype.

3. Are blue eyes a genotype or phenotype? phenotype

4. What is the difference between homozygous and heterozygous? Homozygous is the pairing of two alleles that are the same. Ex. AA, aa Heterozygous is the pairing of two alleles that are different. Ex. Aa

5. Free earlobes are dominant over attached lobes. Cross a heterozyous person with a person who has attached lobes. What percentage of the offspring would have attached earlobes? 50% A a a Aa aa

6. Free earlobes are dominant over attached lobes. Cross a heterozyous person with a person who has attached lobes. What is the genotypic ratio of the offspring? Aa:aa 1:1

7. What is the difference between a monohybrid and dihybrid cross? Monohybrid involves one trait. Ex. Aaxaa Dihybrid involves two traits. Ex. AaCcxAAcc

8. Body evidence containing DNA (fluids,etc.) are analyzed using electrophoresis and some of the DNA is matched to the DNA of a crime suspect. DNA fingerprinting. Can also be used to determine paternity of a child.

9. How many squares would the Punnett square for the following cross have? AaBbxAaBb 16 It is a dihybrid cross.

10. Diagnosing disease by staining, arranging and comparing chromosomes according to staining patterns, size and shape. What is this called. Chromosomal analysis A karyotype is a picture of the chromosomes that can be used for analysis.

11. What is the function of mitois? Mitosis produces 2 diploid daughter cells, each with a full set (diploid) of chromosomes. Ex. Skin cells, liver cells.

12. What is the function of meiosis? Meiosis produces 4 daughter cells that have half (haploid) the number of chromosomes of a normal body cell. Ex. Germ cells like sperm and ova. Meiosis occurs in the reproductive structures of the organism.

13. How many squares are required for a Punnett square of this cross? AAxaa 4 It is a monohybrid cross.

14. When chromotid pairs exchange genes during meiosis it is called… Crossing over. Crossing over increases the genetic variability of the offspring.

15. How many times does DNA replication occur in meiosis? Mitosis? Once in both

16. How many times does cell division occur in meiosis? Mitosis? twice once

17. In humans, free earlobes are dominant over attached lobes and dark hair is dominant over light hair. Cross a person who is homozygous for free lobes and dark hair with a person who is heterozygous for lobes and hair color. What are the genotypic and phenotypic percentages of the offspring. Parent cross AABB x AaBb AB AB AB AB AB AABB Ab AABb aB AaBB ab AaBb AABB-25%, AABb-25%, AaBB-25%, AaBb-25% Free lobes and dark hair 100%

18. In cats, coat color is determined by a sex linked trait. Black and orange coat color are codominant. A cat with both colors produces a multicolored pattern called calico. Cross a heterozygous female with a male who is orange. What are the genotypes and phenotypes of the offspring? Why can’t males be calico? B-black R- orange XB XR XR XBXR XBXR Y XBY XRY XBXR- 50% Calico females XBY- 25% Black males XRY- 25% Orange males Males cannot be calico because they only inherit one X and the coat color trait is not located on the Y chromosome.

19. Describe this individual: Aa Heterozygous dominant

20. Describe this individual: aa Homozygous recessive

21. Recessive traits can skip a generation. Describe the parent cross that would not express the recessive trait in it’s phenotype but would express it in the next generation. AaxAa A a A AA Aa a Aa aa 25% recessive phenotype aa

22. Color blindness is the result of a sex linked recessive trait. Describe the phenotype for this genotype: XHXh Female Normal Carrier

23. Does Aa represent a genotype or phenotype? genotype