Exam 8: Chromosome Mutations: Variation in Number and Arrangement

Trisomy 21,or Down syndrome,occurs when there is a normal diploid chromosomal complement but one extra)chromosome 21.While there is reduced fertility in both sexes,females have higher fertility than males.Van Dyke et al.1995; Down Syndrome Research and Practice 32 : 65- 69 summarize data involving children born of Down syndrome individuals.Given the fact that conceptuses with 48 chromosomes four #21 chromosomes are not likely to survive early development,what percentage of surviving offspring would be expected to have Down syndrome if both parents have Down syndrome?

Inversion heterokaryotypes are often characterized as having reduced crossing over and reduced fertility.Assume that you were examining a strain of organisms you knew to be inversion heterokaryotypes and saw a relatively high number of double chromatid bridges extending between anaphase I nuclei,as indicated in the following drawing.What is the product of this type of inversion loop?

Colchicine is an alkaloid derived from plants.What is its effect on chromosome behavior?

Assume that an organism has a haploid chromosome number of 7.There would be ____chromosomes in a monoploid individual of that species.

Recently,a gene located on chromosome 3 in humans,FHIT,has been shown to be associated with the significant human malady known as ____ .

Describe double Bar mutations in Drosophila melanogaster.

A son is born with Kleinfelter's syndrome and hemophilia.His father was normal and his mother was a carrier for the recessive X- linked blood clotting disorder.What occurred in meiosis to produce this genetic outcome?

What is formed when meiosis occurs in an individual who is heterozygous for an intercalary deletion?

Assume that an organism has a diploid chromosome number of 14.There would be ____chromosomes in a tetraploid.

Gene amplification is the basis for____ .

Noninvasive prenatal genetic diagnosis is sometimes preferred to amniocentesis because ____

Which of the following is an example of an endopolyploid?

Which of the following statements is TRUE?

What is the outcome of nondisjunction in meiosis I?

A genomic condition that may be responsible for some forms of fragile X syndrome,as well as Huntington disease,involves____ .

What experiment led to the identification of the DSCR Down Syndrome Critical Region ?

The condition that exists when an organism gains or loses one or more chromosomes but not a complete haploid set is known as____ .

What is NOT a potential consequence of a copy number variation?

Although the most frequent forms of Down syndrome are caused by a random error,nondisjunction of chromosome 21,Down syndrome occasionally runs in families.The cause of this form of familial Down syndrome is ____.

A ____ inversion is one whose breakpoints do not flank the centromere.