BISC 202 Lecture 6: Pedigrees Summary

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coffeegrasshopper724

10 Dec 2018

School

Simon Fraser University

Department

Biological Sciences

Course

BISC 202

Professor

Michael Hart

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Document Summary

Recessive: 2 normal parents with affected offspring. If both the parents are carriers (aa), the child will have a 25% chance to get 2 mutant recessive alleles and therefore be affected (aa) Dominant: 2 affected parents with normal offspring. If the both the parents are carriers (aa), the child will have a 25% chance to get 2 wildtype recessive alleles and therefore be normal (aa) If the mother is a carrier (xaxa), she will pass one of the x chromosomes to the son, therefore there is a 50% chance that the son will be affected (xay) If the father is affected (xay), he will pass the x chromosome to the daughter, but the daughter gets another x chromosome from her mother. The maternal x chromosome could give the daughter a backup as long as it carriers the wildtype dominant allele (xaxa)

Related Questions

The following question is a sex-linked trait. Review the patterns of inheritance of sex-linked traits before answering the following questions. Make sure to indicate chromosomes and alleles in your answers when necessary.

Hemophilia is a caused by a recessive mutation found on the X chromosome in humans. The recessive allele (X^h) is associated with abnormal blood clotting (hemophilia), while the dominant allele (X^N) causes normal blood clotting.

A man with normal blood clotting and woman who is heterozygous are going to have a child. What is the probability of an offspring who is a carrier of hemophilia, and if so, the sex(es) of the offspring?

A. Chances are 25% of a son who is a carrier

B. There is no chance of an offspring who is a carrier

C. Chances are 50% of either a son or a daughter who is a carrier

D. All offspring, male or female, will be carriers

E. Chances are 1 in 4 of a daughter who is a carrier

2. Two fruit flies, one with red eyes and one with white eyes mate and have an offspring with white eyes. Having red eyes is a dominant trait (R) while white eyes (w) is recessive. Based on this information, what must be the genotypes of the parental white-eyed fruit fly and the parental red-eyed fruit fly?

A. Red-Eyed fruit fly: Rw

White-eyed fruit fly: ww

B. Red-Eyed fruit fly: RR

White-eyed fruit fly: wR

C. Red-Eyed fruit fly: R

White-eyed fruit fly: w

D. Red-Eyed fruit fly: rr

White-eyed fruit fly: wr

E. Red-Eyed fruit fly: RR

White-eyed fruit fly: ww

A study of X-chromosome traits in pedigrees showing affected persons and both their parents provides some indication of the source of the X-chromosome in aneuploid individuals, individuals with abnormal chromosome numbers due to non-disjunction during gametogenesis. In one family, unaffected parents produce 4 children: two normal females, one normal male and one red-green color blind male. The affected male has an XXY chromosome constitution. Red-green color blindness is a recessive trait. Indicate the source of the X-chromosome in this male and diagram the meiotic event giving rise to the affected male. If possible, indicate whether the event occurred in meiosis I or meiosis II.

carmineclam925

18. Which of the following statements about a pedigree would be most definitive in differentiating an AD from an XLD pattern of inheritance?

	A.	Affected males and females are seen in all generations.
	B.	An affected male has only one daughter, and that daughter is affected.
	C.	There are two instances where an uaffected parent has an affected parent and an affected child.
	D.	An unaffected male with an affected father has three affected daugthers.
	E.	An unaffected mother with an affected mother has one affected daughter and one affected son.

20. If a man and his maternal uncle express an X-linked recessive disease, we can draw the following conclusion(s):

	A.	His maternal grandma was a carrier
	B.	All of his maternal uncles must be affected
	C.	All of his daughters will be carriers
	D.	All of his sisters are carriers
	E.	All of his maternal aunts are carriers
	F.	A and C
	G.	A and D

BISC 202 Lecture 6: Pedigrees Summary

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