Chapter 15 Quiz; The Chromosomal Basis of Inheritance

DNA methylation that silences particular genes and DNA methylation that activates particular genes

What appears to be the mechanism for genomic imprinting?

trisomic; aneuploidy

When an individual has an additional chromosome, that chromosome set is called ____________, and the condition is known as _________________.

genes occupy specific positions on chromosomes, homologous chromosomes segregate from each other during meiosis, and chromosomes assort independently during meiosis

The chromosome theory of inheritance states that ____________.

unlinked

You perform a testcross using F1 dihybrid flies. If, in the resulting offspring, the percentages of parental and recombinant offspring are about the same this would indicate that the two genes are _________________.

two; Barr body; random

X inactivation occurs when there is/are at least _____________ X chromosomes present in an individual, forming a structure called a _________________ by a _____________ event.

orders genes on a chromosome based in recombination frequencies

A linkage map ______________.

To express an X-linked recessive allele, a female must have two copies of the allele.

Duchenne muscular dystrophy is caused by a sex-linked recessive allele. Its victims are almost invariably boys, who usually die before the age of 20. Why is this disorder almost never seen in girls?

50%

In werewolves (hypothetically), point ear (P) are dominant over round ears (p). The gene is on the X chromosome. (Sex determination in werewolves is the same as for 'other' humans). A certain female werewolf has pointy ears even though her father had round ears.

What percentage of her sons will have round ears if she mates with a werewolf with round ears?

embryonic development

Genomic imprinting in mammals appears to primarily affect genes involved in ________________.

male white-eyed; Morgan

Compared to peas, fruit files were through to have no variations, until the discovery of a _______________ fly by _____________.

a mosaic

Female mammals have two X chromosomes, one from their mothers and one from their fathers. During X inactivation, one X chromosome in each embryonic cell is randomly inactivated; therefore, all of the tissues that arise from that cell have the same inactivated X chromosome. Female mammals are therefore considered to be _____________ of the maternal and paternal cells.

Matings of soft ray males and bony ray females give different results from the matings of bony ray males and soft ray females

In certain fish, fin rays (supporting structure for the fins) can be either bony or soft in adult fish. Sex linkage in a fish is similar to that in humans. What evidence would most strongly support the idea that the ray locus is on the X chromosome?

the most common phenotype thought to be found in the natural population

Wild type refers to ___________.

two; X; Y; one; haploid

In humans, a normal male's somatic cells will have __________ set(s) of chromosomes and sex chromosomes designated as _______________ and _______________, while in bees and ants, a normal male's somatic cells have ____________ set(s) of chromosomes, which are ______________.

Aneuploidy

In Klinefelter syndrome, individuals are phenotypically male, but have reduced sperm production and may have some breast development in adolescence. The cells of Klinefelter individuals have two X chromosomes and on Y (they are XXY instead of XY)

This occurs because of what meiotic error?

chromosomal theory of inheritance ; segregation; independent assortment

The ____________ states that genes have specific positions on chromosomes and that chromosomes undergo both _____________ and ________________.

red; red

In a cross between wild-type (red-eyed) female flies and mutant white-eyed male flies, the F1 generation should always produce females with ___________ eyes and males with _________eyes.

the mother

In an X-linked, or sex-linked, trait, it is the contribution of ___________ that determines whether a son will display the trait.

be greater than

When crossing over occurs between two linked genes in an F1 dihybrid testcross, the frequency of the parental types will always __________ the frequency of the recombinant types when compared to Mendel's unlinked genes

are located near each other on the same chromosome.

Linked genes ___________.

A single mating can produce many offspring and Drosophila chromosomes can be easily distinguishable under a light microscope.

Why did Morgan choose Drosophila for his genetics experiments?

aneuploidy

Example of alteractions of chromosomal structures include all of the following expect ___________.

-translocation

-dupulications

-aneuploidy

-deletions

-inversions

Non-disjunction; homologous chromosomes; sister chromatids

______________ is the failure of ________________ to separate in meiosis I or the failure of ______________ to separate in meiosis II.

genomic imprinting

Gene silencing is called_____________.

may have subnormal intelligence or be at risk for learning disabilities

Individuals with an extra X chromosome _____________.

aneuploidy; trisomic

Down syndrome is an example of _________, and the child is _____________ for chromosome 21.

segregation; homologous pairs; independent assortment; alleles; independently

The ability to observe meiosis in gamete production supported Mendel's first law of ________________, which applies when __________ separate and supported Mendel's second law of _______________, which applies when ___________ sort ____________.

She is XXX

With a microscope, you examine some somatic cells from a woman and notice that each nucleus has two Barr bodies. What can you infer abut the sex chromosomes in this individual?

fathers pass X-linked alleles only to their daughters, and mothers pass X-linked alleles to bother their daughters and their sons

In X-linked patterns of inheritance, ______________.

Either her mother was a carrier or her father had hemophilia

Queen Victoria was a carrier of a recessive sex-linked allele for hemophilia. Which of the following possibilities could explain the presence of the hemophilia allele in her genotype?

-Either her mother was a carrier or her father had hemophilia.

-Either her mother was homozygous dominant or her father had hemophilia.

-Either her mother was a carrier or her father had a dominant allele.

-Both her mother and her father had hemophilia.

none of the above