Chapter 5: Sex Determining and Sex Chromosome Flashcards
True or False. The continuity of a sexually reproducing species depends on an efficient union of gametes during fertilization. In turn, successful fertilization depends on some forms of sexual differentiation.
True
He identified nuclear structure in the sperm of certain insects, which he labeled the X-body.
Hermann Henking
He showed that some of the sperm in grasshoppers contain an unusual genetic structure, called a heterochromosome.
Clarence Mclung
Sex determination in Protenor butterfly.
- Female diploid = 14; gametes = 7 (six somatic and 1 X)
- Males diploid = 13; gametes = either 6 (all somatic) or 7 (6 somatic, 1 X)
- Fertilization by X-bearing sperm results in female offspring, and fertilization by X-deficient sperm results in male offspring.
Sex determination in Lygaeus turcicus.
- Female diploid = 14; gametes = 7 (six somatic and 1 X)
- Males diploid = 14; gametes = 7 (6 somatic 1 X or Y))
- Fertilization by Y-bearing sperm results in female offspring, and fertilization by X-bearing sperm results in male offspring.
The sex that produces unlike gametes. Their gametes determine the sex of the progeny.
Heterogametic sex
Manifestation of secondary characteristics of both sexes in one individual.
Intersexuality
Additional copy of the X chromosome in addition to the normal diploid set (46, XY)
Klinefelter syndrome (47, XXY)
True or False. The presence of at least one Y chromosome is sufficient to express human maleness.
True
Individuals with this syndrome most often have only 45 chromosomes, including just a single X chromosome.
Turner syndrome (45, X)
True or False. Individuals with Klinefelter syndrome are genetically females and individuals with Turner syndrome are genetically male.
False. Klinefelter individuals are males due to the presence of the Y chromosomes and Turner individuals are female due to the absence of the Y chromosome.
Individuals whose somatic cells display two different genetic cell lines, each exhibiting a different karyotype.
Mosaic
Two possible karyotypes of mosaic individuals.
45, X/46, XY
45, X/46, XX
Karyotype of triplo-X individual.
47, XXX
Karyotype of tetra-X individual.
48, XXXX
What condition do mosaic individuals have?
Turner syndrome
Above-normal height, subnormal intelligence, suffered personality disorder.
47, XYY condition
True or False. Additional Y chromosome predisposes males to behavioral problems.
True
Precursor tissue of the gonadal organs.
Gonadal primordia
Gonadal primordia arise as a pair of what structure associated with each embryonic kidney during the fifth week of gestation?
Gonadal ridges
True or False. During the early stages of fetal development, the sex of the embryo is male.
False. The sex of the embryo is hermaphroditic since reproductive structures cannot be distinguished, and the gonadal ridge tissue can develop to form male or female gonads.
As development progresses, primordial germ cells migrate to these ridges forming what structures.
Cortex and Medulla
The outer layer of tissues in an organ.
Cortex
The inner layer of tissues in an organ.
Medulla
The cortex is capable of developing into what structure?
Ovary
The medulla may develop into what structure?
Testis
Which undifferentiated duct differentiates into other organs of the male reproductive tract.
Wolffian ducts
Which undifferentiated duct differentiates into other organs of the female reproductive tract.
Mullerian ducts
Gonadal ridges are called what because they can form either ovaries or testis?
Bipotential gonads
True or False. The presence of the Y chromosome in the cells of the gonadal ridge does not interfere with the development of female reproductive organs.
False.