Exam 2 Flashcards
TDF
Testis Determining Factor
XX SRY+
-Male External Characteristics
-Shorter than average
-Small testes
-Infertile = Lack AZF gene (sperm production gene)
-Usually male gender identity
-May need additional testosterone at puberty
Swyer Syndrome
- XY SRY-
-Female external sex characteristics
-Usually female gender identity
Uterus and fallopian tubes develop normally
-Hormone supplementation required for proper breast development and uterine growth
-Gonads are undeveloped clumps of tissue
-can only become pregnant via a donated egg or embryo
What transcription factor is believed to behave as the master switch for controlling the genes involved in sexual differentiation?
TDF
Androgen Insensitivity Syndrome (AIS)
-XY AR-
- Mutant AR gene
-the androgen receptors don’t work properly and the cells are less responsive to testosterone
What does Complete AIS result in?
-Female external characteristics
-Usually female identity
-No uterus = infertile
-Undescended testes located in the pelvis or abdomen
What is the notation used when a female is the heterogametic sex?
Male = ZW
Female = ZZ
What is the process of G-banding?
-Colchine arrests cells in metaphase
-Then treaed with trypsin
-Lastly, Giemsa stained
Karyotype
Ordered array of the chromosomal complement of a cell
How are chromosomes arranged in a karyotype?
-Distinguished by size
-Centromere position
-Banding pattern
Arranged largest to smallest
Aneuploidy
Individual chromosomes are either missing, or present extra copies
Klinefelter Syndrome
-XXY
-Tall with long arms and legs with large feet and hands
-Testes are rudimentary and fail to produce sperm
-Slight breast enlargement and hips often rounded
-Intelligence below normal range
Turner Syndrome
-X
-Female external genitalia and internal ducts
-Ovaries are rudimentary
-Normal intelligence
-Short stature
-Flat underdeveloped breasts
-Broad, shieldlike chest
Triplo-XXX
-47,XXX
-Three X chromosomes along with a normal set of autosomes
-Female phenotype
-1/1000 live births
-Mild symptoms: taller than average and sometimes a slight learning delay
XYY Condition
-Males over 6 feet tall
-Subnormal Intelligence
-Some evidence of predisposition to violence
Lyon Hypothesis
-Mary A. Lyon, 1925-2014
-Inactivation and creation of Barr body is random and all descendant cells have same inactivation
What hypothesis best explains the fur color in calico and tortoiseshell cats?
Lyon Hypothesis
What is the mechanism of action for the inactivation of an X chromosome?
-X-inactive specific transcript (XIST) gene
-Located in end of X chromosome p arm in humans
-Critical to X inactivation
-only expressed on inactivated X chromosome
Euploidy
-Describes a cell that has an exact multiple of the haploid number (n) of chromosomes
Monosomy
2n-1
-loss of one member of a homologous pair
Disomy
2n
Trisomy
2n+1
-Gain of one chromosome, resulting in three homologous chromosomes
tetrasomy
2n+2
-Gain of two homologous chromosomes, resulting in four homologous chromosomes
Diploidy
2n
Triploidy
3n
tetraploidy
4n
Trisomy 21
-Down Syndrome
-Low muscle tone
-Small stature
-Upward slant to the eyes
-A single deep crease across the center of the palm
-Intellectual disability
Polyploidy
Addition of entire chromosome sets
Allopolyploidy
Polyploidy in which extra chromosome sets are derived from two or more species
Autopolyploidy
Polyploid in which extra chromosome sets are derived from the same species
Nullisomy
Loss of both members of a homologous pair
Chromosome Rearrangement
Change in chromosome structure
Chromosome Duplication
Duplication of chromosome segment
Chromosome Deletion
Deletion of a chromosome segment
Chromosome Deletion
Deletion of a chromosome segment
Inversion
Chromosome segment inverted 180 degrees
Paracentric Inversion
Inversion that does not include the centromere in the inverted region