Bell Work 3/5

1. Bell Work 3/5 In humans, dimples are dominant over no dimples. A father has dimples, the mother does not have dimples, all the children have dimples. Give the probable genotypes of all persons concerned. SET UP PUNNETT SQUARE!

2. Bell Work 3/6 The following genotypes are written incorrectly: AabB and ABAb. Write them correctly.

3. 1-3. In horses, some of the genes for hair color are incompletely dominant. Genotypes are as follows: brown horses are BB, white horses are bb and a Bb genotype creates a yellow-tannish colored horse with a white mane and tail, which is called “palomino”. Show the genetic crosses between the following horses and record the genotypic and phenotypic percentages: a. brown x white b. brown x palomino c. palomino x palomino Bell Work 3/7 Genotypic Genotypic Genotypic %: ________________ %: ________________ %: ________________ Phenotypic Phenotypic Phenotypic %: ________________ %: ________________ %: ________________ 4. Can palominos be considered a purebred line of horses? Why or why not?

4. Bell Work 3/8 A segment of DNA shows bases in this order AGT CAC GCA, complete the corresponding DNA strand: TCA GTG? • ACG • CGT • GCA • TGC

5. Modes of inheritance A) Autosomal when genes are on NON sex chromosomes (autosomes) 1. Mendelian – 1 allele dom over another

6. 2. Incomplete dominance – neither allele is fully dominant, results in blended phenotype Ex: In flowers, red color is incompletely dominant to white. If a homozygous red flower is crossed with a homozygous white flower… R = Red W = White (in incdom use diff letter!) RR x WW W W RW RW R Phenotypic ratio: _0__:_4_:_0_ (Red)(Pink)(White) RW RW R

7. 3. Co-dominance – 2 alleles are equally dominant, both show up! Ex: Roan horses. Black (B) is codominant with white(W); If a black horse mates with a white horse…. B B Phenotypic ratio: __0_ : _4_ : __0_ W BW BW BW BW W

9. 4. Multiple alleles – more than 2 allele forms for 1 gene example blood types in humans. • In humans, blood type ‘A’ (IA) is codominant with blood type ‘B’ (IB) . BOTH are dominant to blood type ‘O’ (i)

10. Multiple Allele Traits • What are the two possible genotypes for a person with A blood? • What genotype does a person with AB blood have? • What genotype does a person with O blood have? • What are the two possible genotypes for a person with B blood?

11. Practice#1 If you were to cross a female with an AB blood type with a male with O blood type, could you end up with a child that has an O blood type?

12. Practice 2: If you were to cross a female with A blood type with a male whose blood type is B, could you end up with a child who has an O blood type?

13. Practice 3: A woman with type A blood is claiming that a man with type AB blood is the father of her child who is type B. Could this man be the father of the child? Assuming that he is the father , what must the mother’s genotype be?

14. Practice 4:Coat color in rabbits is inherited as a series of multiple alleles. In the case of rabbits, there are four alleles and each one is expressed with a different phenotype. Look over the summary

15. C) Sex-linked traits – when gene is located on a sex chromosome (allosomes) 1. Y chromosome genes determine testes development 2. Gender determination in humans a) XX = Female (♀) b) XY = Male (♂)

17. 3. X-linked; genes are on X, females get 2 copies (XX), male only get 1 (XY) a) Traits passed from mother b) show sex chromosomes when doing cross c) Separate phenotypic ratio by gender

18. c) Ex – Duchenne’s muscular dystrophy is a recessive disorder which is X-linked. A woman who is heterozygous for the trait marries a healthy man: D – Healthy d-Duchenne’s MD (Mother) XDXd x ___XDY__ (Father) Y XD Females: __2__:__0__ XD XDXD XDY Males: __1__:__1__ Xd XDXd XdY

19. Practice: Red-Green color blindness shows X-linked recessive inheritance. If a woman who was a carrier married a male that does not have the disease, what could you expect in offspring?

20. F) Polygenic inheritance – multiple GENES control 1 trait, may interact. Ex: Height has many genes. Skin color. Also, fur color and or pattern in many animals Height is controlled by many genes. Example Recessive epistasis in Labs AABbCc You receive 1 allele for each height gene from each Parent. In epistasis, 1 gene depend on another.

21. Pedigrees – way to track traits through generations A) Symbols Normal male Normal female Affected male Affected female Carrier (Heterozygous {Recessive ONLY}) Death due to trait Marriage

22. B) Determining inheritance 1. Autosomal dominant – A=affected, a=normal a) USUALLY every generation b) EVERY affected offspring has at least 1 affected parent

23. 2 Autosomal recessive a) MAY skip generations b) If affected offspring with 2 healthy parents MUST BE RECESSIVE

24. 3. Sex-linked recessive a) Males affected MUCH more than females! b) MUST SHOW sex chromosomes when labeling

25. Warm up:

26. C) Assigning genotypes 1. WRITE SYMBOLS 2. Begin w/homozygous recessive individuals! 3. Work your way through 4. Label carriers for recessive diseases

28. Chromosomal abnormalities A) Mutations (change in a gene or portion of chromosome) 1. Affects MANY genes!!!!!!!!!!!!!!!!!!!!!!! 2. Effects typically severe

29. Duplication – Part of chromosome copied too many times Deletion: Part of chromosome skipped when copied

30. B)Nondisjunction – Chromosomes don’t split evenly during meiosis 1. If during Meiosis I – 0% chance of normal gametes 2. If during Meiosis II, 50% normal, 50% abnormal

31. C) Detecting nondisjunction 1. Post natal – cells analyzed 2. Prenatal: Amniocentesis – cells extracted from fetus prior to birth 3. Karyotype/karyogram Chromosomes stained, photographed thru microscope, enlarged, analyzed

32. Slight increase in frequency of nondisjunction in older males but not as significant

33. D) Effects of nondisjunction 1. Most result in miscarriage/stillbirth 2. Down’s syndrome a) Cause: Trisomy 21 (3 copies of the 21st chromosome pair)

34. b) Lifespan is improving http://grownmannow.com/wp-content/uploads/2011/05/down-syndrome-increasing-longevity.jpg

36. 3. Klinefelter’s syndrome Trisomy of the sex chromosomes (XXY) 4. Turner’s syndrome (Monosomy X) (X_)