BIOL207 Lecture Notes - Lecture 12: Punnett Square, Chromosome, Organelle

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bronzesalmon403

13 Oct 2013

School

University of Alberta

Department

Biology (Biological Sciences)

Course

BIOL207

Professor

Mike Harrington

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Document Summary

Females are either heterozygous or homozygous: heterozygous: same gene different alleles. Males are hemizygous ( hemi- = half: the only have 1 x-chromosome out of the 2 sex chromosomes. The white eye gene in drosophila is x-linked and recessive: heterozygous females will have red eyes. Red eyed females and white eyed males will be the two exhibited phenotypes of the next generation. Here"s the punnet square to show how this comes about: There is an x-linked red gene: o = orange, o = black. Female cats that are heterozygous for this gene will exhibit orange and black spotted coats: homozygous for o" will give them orange coats, homozygous for o" will give then black coats. For males, though, it is one or the other because they only have one x chromosome. If x chromosome has o" allele, cat will be orange and vice versa if the allele is.

Related Questions

If the white-eye trait were X-linked dominant, rather than X-linked recessive, what result would you expect when crossing a heterozygoud white-eyed female with a white-eyed male?

Answer Choices

1) In each sex, half of the offspring will have red and half of the offspring will have white eyes.

2) all red-eyed progeny

3) all red-eyed males with half of the females having white and half of the females having red eyes.

4) all white-eyed females with half of the males having white and half of the males having red eyes.

5) all red-eyed females with half of the males having white and half of the males having red eyes

Thank you

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

In Drosophila, the X-linked recessive mutation vermillion (v) causes maroon colored eyes, in contrast to the bright red eyes of wild type. A separate autosomal recessive mutation, suppressor (s), causes flies to produce no eye pigmentation (white eyes) regardless of the vermillion genotype. You cross a true-breeding vermilion female with a true-breeding white-eyed male who is hemizygous (wild-type) for the vermillion gene.

A) What are the resulting F1 phenotypes for each sex?

B) What are the resulting F1 genotypes?

BIOL207 Lecture Notes - Lecture 12: Punnett Square, Chromosome, Organelle

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