Chapter 24

T or F: Genetic recombination is a frequently observed event that is fairly predictable.

false

During meiosis I, _____ separate and move towards opposite ends of the poles.

homologous chromosomes

Nondisjunction can occur during ____________ I, when both members of a homologous pair are pulled into the same daughter cell.

meiosis

For this reason, it is more likely that ______ are afflicted with sex-linked diseases, because whatever allele is carried on their ____________ X chromosome(s) is expressed.

men; one

If an egg that contains 22 chromosomes instead of 23 chromosomes is fertilized by a normal sperm, _____ is said to have occurred.

monosomy

On the other hand, if an egg with 22 chromosomes is fertilized by a normal sperm, the result is a ____________ because one chromosome is present only in a single copy

monosomy

During meiosis I, if both members of a homologous pair go into the same daughter cell, _____ is said to occur and no normal gametes are produced.

nondisjunction

During meiosis II, if the sister chromatids fail to separate and both daughter chromosomes go into the same gamete, _____ is said to occur. Half the gametes have 2n+1 chromosomes while the other half have 2n-1 chromosomes.

nondisjunction

This is because on ____________ alleles, the allele is only carried on the ____________ chromosome and not the ____________ chromosome.

sex-linked; x; y

During meiosis II, _____ separate and move towards opposite ends of the poles.

sister chromatids

It can also occur during meiosis II if ____________ fail to separate, resulting in both daughter chromosomes entering the same gamete.

sister chromatids

Because too many chromosomes are tolerated more than a deficiency in chromosome number, there are more ____________ disorders than monosomy disorders in humans.

trisomy

If an egg that contains 24 chromosomes instead of 23 chromosomes is fertilized by a normal sperm, _____ is said to have occurred.

trisomy

If an egg with 24 chromosomes is fertilized by a normal sperm, the result is a _______ due to one chromosome being present in three copies.

trisomy

T or F: Once a cell undergoes X chromosome inactivation, all of its daughter cells will have the same X chromosome inactivated.

true

T or F: The closer genes are to one another on a chromosome, the more likely they are to be inherited together.

true

That means that females can pass down mutated alleles to offspring through ____________ X chromosome(s), while males can pass down alleles through ____________ X chromosome(s)

two; one

Females with only one X chromosome have the genotype _____ and are said to have _____ syndrome. They tend to have distinguishing physical characteristics and _____ reproductive organs. They will not undergo puberty or menstruate without _____ replacement therapy.

xo; turner; underdeveloped; sex hormone

Males with an extra Y chromosome have the genotype _____ and are said to have _____ syndrome. They tend to be tall, have persistant acne, and have speech and reading problems.

xxy; jacobs

Males with an extra X chromosome have the genotype _____ and are said to have _____ syndrome. Affected individuals often receive _____ supplements at puberty and would require further treatment in order to father children.

xxy; klinefelter; testosterone

Females with an extra X chromosome have the genotype _____ and are said to have _____ syndrome. They tend to be tall and lean and may have motor or language difficulties and/or menstrual issues, but more often there is no distinct phenotype.

XXX; poly x

Sex-linked alleles have a different pattern of inheritance compared to those found on ____________ chromosomes.

autosomal

A cell with three X chromosomes will contain _____.

2 barr bodies

In both cases, gametes are created that have either received an extra chromosome resulting in __ chromosomes present, or have lost a chromosome resulting in __ chromosomes present.

24; 22

Although humans normally possess _____ chromosomes, some individuals are born with too many or too few of these chromosomes, in many cases due to a process called _____.

46; nondisjunction