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EBIO 1030 Lecture Notes - Lecture 11: X-Inactivation, Punnett Square, Y Chromosome

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lemongnu981
30 Jan 2019
School
CU-Boulder
Department
Ecology & Evolutionary Biology
Course
EBIO 1030
Professor
Caitlin Kelly

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Document Summary

Sperm cells with an x or a y determine the genetic sex of human offspring. Sry gene on y chromosome leads to testes development. In each female cell, one x-chromosome is inactivated and is condensed into a. Ensure s an equal expression of genes from the sex chromosomes since females have 2 x-chromosomes and males have only 1. Most sex-linked disorders are recessive ( x linked recessive) Less likely to express trait: must have two defective x chromosomes. Men are more likely to express the trait. One x chromosome - will express whatever is on that chromosome, even a single recessive allele. Y chromosome is small and missing a lot of genes. Example of an x linked recessive disorder. Red green color blindness: altered structure of photoreceptors in the eyes. Affects 8 percent of men and less than 1 percent of women\ Diseases caused by recessive, sex-linked alleles should be more commonly expressed in.

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Related Questions

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. What is the chromosome theory of inheritance?
2. Understand how independent assortment can cause gametes to have four combinations of alleles when an individual is heterozygous for two genes on two different chromosomes.
3. What are linked characters and linked genes? Understand why linked genes will not independently assort.
4. How can crossing over affect linked genes?
5. What are recombinant gametes?
6. Define recombinant frequency. Be able to use the recombinant frequency to determine how close two genes are on a chromosome.
7. What is a linkage map?
8. What is the function of the SRY gene on the Y chromosome? What happens if you don't have this gene?
9. Know how sex is determined in mammals, birds, bees and ants, and reptiles.
10. How many autosomes and sex chromosomes do normal human haploid and diploid cells have?
11. What does it mean for a gene to be X-linked or Y-linked?
12. Be able to answer word problems and fill out a Punnet square involving an X-linked recessive trait.
13. Which sex is more likely to have an X-linked recessive disorder? Understand why.

P.s The most simple answer would be preferable. I would be copping the notes over that you will provide to my noteb book and add my details to it.
According to the multiplication rule of probability, the chance of crossing two pea plants that are heterozygous for height and have none of four offspring showing the recessive short phenotype is:A. ¼ × ¼ × ¼ × ¼.

B. ¾ × ¾ × ¾ × ¾.

C. (¼ × ¼ × ¼ × ¼) + (¾ × ¾ × ¾ × ¾).

D. ¼ + ¼ + ¼ + ¼.

E. None of the above.

What characteristic is exhibited by an X-linked trait?

a) Only females have the trait.
b) Females inherit X-linked traits from their maternal parent only.
c) Females can inherit a gene for an X-linked trait from either parent.

d) Males inherit X-linked traits from their paternal parent only.

e) Males can inherit a gene for an X-linked trait from either parent but normally inherit it from their fathers.
What characteristic is exhibited by a Y-linked trait?
a) Y-linked traits appear only in male offspring of men with the trait.
b)Y-linked traits are only passed from father to son.
c) Y-linked traits can be passed from mother to son.
d) Both A and B are characteristics of Y-linked traits.
e) Both A and C are characteristics of Y-linked traits.
Which of the following codes for a phenotypic human male?
a) XO with a copy of SRY gene on an autosomal chromosome?
b) XXYY with one copy of the SRY gene deleted?
c) XX with a copy of SRY gene on an autosomal chromosome?
d) All of the above sex compliments results in a person with a sex phenotype of male.
e) XY with the SRY gene located on an autosomal chromosome?
In Drosophila, yellow body is due to an X-linked gene (Xy) that is recessive to the gene for gray body (X+). A homozygous gray female is crossed with a yellow male. What are the genotypes of the F1 progeny?
In some goats, the presence of horns is produced by an autosomal gene that is dominant in males and recessive in females. A horned female is crossed with a hornless male. The F1 offspring are intercrossed to produce the F2. What proportion of the F2 females will have horns?
a)1/2
b)3/4
c)1/4
d) All
None
a) Females are X+X+; males are X+Y.
b)Females are X+X+; males are XyXy.
c)Females are X+X+; males are XyY.
d) Females are X+Xy; males are XyY.
e) Females are X+Xy; males are X+Y.

Females inherit X-linked traits from their maternal parent only.
Females can inherit a gene for an X-linked trait from either parent.
Males inherit X-linked traits from their paternal parent only.
Males can inherit a gene for an X-linked trait from either parent but normally inherit it from their fathers.
Males can inherit a gene for an X-linked trait from either parent but normally inherit it from their fathers.