BIOL 222 Lecture Notes - Lecture 5: Rickets, X-Inactivation, Hypophosphatemia

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7 Sep 2016

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Biol 222 lecture 5 sex chromosomes. Xx/x0: females: 2 x chromosomes (xx) homogametic, males: 1 x chromosome (x) heterogametic. Meiosis in the male: of gametes get an x, the other half do not get a sex chromosome. Xx/xy: females: 2 x chromosomes (xx) homogametic, males: 1 x chromosome, 1 y chromosome (xy) heterogametic. Present in many animals, including humans and drosophila (fruit flies) Zz-zw: females: 1 z and 1 w chromosome (zw) - heterogametic sex, males: 2 z chromosomes (zz) - homogametic sex. Present in certain birds, reptiles, insects, amphibians, and fish. Genic sex determination: no sex chromosomes, specific genes on the autosomes determine the sex, present in some plants and protozoans. Environmental sex determination: environmental factors (eg. temperature) determine the sex. Example of differences: in drosophila the x:autosomal chromosome ratio dictates sex. Females have a ratio of 1 and males have a ratio of 0. 5.

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11) CIRCLE ALL CORRECT ANSWERS: Human males are hemizygous for

a) Sxl gene b) pseudoautosomal region of the Y c)SRY d) gene for testis determining factor e) Xist gene

12) The X inactivation center codes for

a) gonadal ridges to form ovaries b) gonadal ridges to form testes c) RNA d) testosterone e) protein enhancing transcription of sex linked genes

13) CIRCLE ALL CORRECT ANSWERS: The pseudoautosomal region is found on

a) autosomes in males b) autosomes in females c) X chromosome d) Y chromosome e) both the X and Y chromosome f) could occur in fruit flies

14) Comparing two monozygotic XX twins to two monozygotic XY twins

a) XX are more identical b) XY are more identical c) monozygotic twins do not occur

EXPLAIN YOUR ANSWER:

15) CIRCLE ALL CORRECT ANSWERS: Butterflies and Habrobracon differ in

a) which sex is homogametic b) which sex is monoploid c) one has sex chromosomes and the other does not d) one produces some gametes by mitosis, the other does not

1. If you had a fruitfly with phenotype A, what test would you make to determine if it was Aa or AA? Explain the different outcomes expected if the fly in question is AA or Aa.

2.The sex of birds, some insects, and other organisms is determined by a ZW chromosomal arrangement in which the males have like sex chromosomes (ZZ) and females are ZW (similar to XY in humans). Assume that a recessive lethal allele on the Z chromosome causes death of an embryo in birds. What sex ratio would result in the offspring if a cross were made between a male heterozygous for the lethal allele and a normal female?

3.A recessive gene for red-green color blindness is located on the X chromosome in humans. Assume that a woman with normal vision (her father is color-blind) marries a color-blind male. What is the likelihood that this couple's first son will be color-blind?

4. One form of hemophilia is caused by a sex-linked recessive gene. Assume that a man with hemophilia marries a phenotypically normal woman whose father had hemophilia. What is the probability that they will have a daughter with hemophilia? (Note: In this problem, you must include the probability of having a daughter in your computation of the final probability.)

5. One form of hemophilia is caused by a sex-linked recessive gene. Assume that a man with hemophilia marries a phenotypically normal woman whose father had hemophilia. What is the probability that their first son will have hemophilia?

amethystgnat408

1. A mother with blood type A has a child with blood type A. Give all possible blood types for the father of this child.

a.) O

b.) B, AB

c.) A, AB

d.) A, B, O

e.) A, B, AB, O

2.) In sesame, the one-pod condition (P) is dominant to three-pod (p), and normal leaf (W) is dominant to wrinkled (w). These characteristics assort independently. A one-pod, wrinkled leaf Ã one-pod, normal leaf cross gave a progeny of 654 one-pod, normal leaf plants and 224 three-pod, normal leaf plants. What are the likely genotypes of the parents in this cross?

		a.) Pp ww Ã Pp Ww
b.)		Pp Ww Ã Pp Ww
c.)		Pp ww Ã Pp WW
d.)		PP Ww Ã Pp ww
	e.)	PP ww Ã PpWw

3.) Honeybees have a haplo-diploid sex determination system where females develop from a fertilized egg (they are diploid, having one allele from the female queen and one allele from the male), and males develop from unfertilized eggs (they are haploid, having only one allele from the queen). Assuming that the queen is heterozygous for a particular gene, what is the probability that a female will inherit the recessive allele from her mother? What is the probability that a male will inherit a recessive allele from his mother?

		a.) The probability that a daughter will inherit a recessive allele from her mother is 50%; the probability that a son will inherit a recessive allele from his mother is 100%.
		b.) The probability that a daughter will inherit a recessive allele from her mother is 100%; the probability that a son will inherit a recessive allele from his mother is 50%.
		c.) The probability that a daughter will inherit a recessive allele from her mother is 50%; the probability that a son will inherit a recessive allele from his mother is 50%.
		d.) The probability that a daughter will inherit a recessive allele from her mother is 100%; the probability that a son will inherit a recessive allele from his mother is 100%.

4.) Human males, with XY chromosomes are _____ and produce two different kinds of gametes, whereas females with XX chromosomes are _____ and produce only one kind.

a.)		homogametic; heterogametic
		b.) pleiotropic: epistatic
		c.) heterogametic; homogametic
		d.) epistatic; pleiotropic

5.) A chi-square test is done to test the hypothesis that a set of data represents a F₂ ratio of 9:3:3:1. The degree(s) of freedom that should be used is:

		a.) 1
		b.) 2
		c.) 3
		d.) 4 I DON'T KNOW HOW TO DO THESE PROBLEMS, I WOULD REALLY APPRECIATE SOME HELP AND EXPLANATION ON HOW TO WORK OUT THESE PROBLEMS. THANK YOU VERY MUCH!!!

BIOL 222 Lecture Notes - Lecture 5: Rickets, X-Inactivation, Hypophosphatemia

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