Karyotyping I Flashcards
It is the number and appearance of chromosomes in the nucleus of a eukaryotic cell.
Karyotype
[3] Karyotype analyzes:
- Sex chromosomes
- Presence or absence of individual chromosomes.
- Nature or extent of chromosomal aberrations.
It is a complete set of chromosomes in a species, or an individual organism.
Karyotype
[2] Karyotypes may be performed by taking:
- blood, bone marrow, or skin sample from adult.
- sample of amniotic fluid or extra-embryonic cells from an unborn child.
(contains stray cells)
amniotic fluid
(from the chorionic villi)
extra-embryonic cells
Once the cells have been obtained for a karyotype, they are mixed with plant-derived chemicals called ____ that stimulate mitosis.
lectins
After the required quantity of cells has been acquired, the cells are treated with a drug called _____ to stop the mitotic process at metaphase.
colchicine
This arrests the action of spindle fiber microtubules; hence ceasing the mitotic process.
Colchicine
Chromosomes may be distinguished from one another based upon several key characteristics:
- the length of the arms of the chromosome.
- shape
- general appearance of the chromosome.
Provides a mechanism to determine if non-dis
junctional diseases, such as Down syndrome (Trisomy21), are present in the fetus.
Karyotype analysis
It also provides a look at the chromosomes to see if there are any missing segments (deletions) or translocations that may have occurred during crossing-over.
Karyotype
A chromosome number that is a multiple of the normal haploid set.
Polyploidy
A chromosomal number that varies by something less than a set.
Aneuploidy
Having three copies of a single chromosome.
Trisomy
35%-70% of early embryonic deaths and spontaneous abortions are caused by this.
Aneuploidy
1 in 170 live births are at least partially what?
aneuploid
5%-7% of early childhood death stare related to?
Aneuploidy
Errors in meiosis.
[poly, tri, tetra]
Polyploidy
Events after fertilization.
[poly, tri, tetra]
Polyploidy
Errors in mitosis.
[poly, tri, tetra]
Polyploidy
Three sets of chromosome.
[poly, tri, tetra]
Triploidy
Most common form of polyploidy.
[poly, tri, tetra]
Triploidy
15%-18% of all spontaneous abortions.
[poly, tri, tetra]
Triploidy
Approximately 75% have two sets of paternal chromosomes.
[poly, tri, tetra]
Triploidy
Probably due to polyspermy.
[poly, tri, tetra]
Triploidy
1% conceptions are triploid but 99% die before birth.
[poly, tri, tetra]
Triplody
Four sets of chromosome.
[poly, tri, tetra]
Tetraploidy
5% of all spontaneous abortions.
[poly, tri, tetra]
Tetraploidy
Extremely uncommon in live births.
[poly, tri, tetra]
Tetraploidy
May result from failure of cytokinesis in the first mitotic division.
[poly, tri, tetra]
Tetraploidy
Life threatening.
[poly, tri, tetra]
Tetraploidy
It is the failure of homologs or sister chromatids chromosomes to separate in meiosis or mitosis.
Non-disjunction
[2] Non-disjunction
- Produces abnormal gametes
- Phenotypic effects of aneuploidy
Lethal condition.
[autosomal’s]
Autosomal monosomy
Aneuploidy during gamete formation produces equal numbers of monosomic and trisomic gametes and embryos.
[autosomal’s]
Autosomal monosomy
Rarely seen in spontaneous abortions and live births.
[autosomal’s]
Autosomal monosomy
Majority are lost early in development.
[autosomal’s]
Autosomal monosomy
Most are lethal.
[autosomal’s]
Autosomal trisomy
50% of cases of chromosomal abnormalities that cause fetal death are autosomal trisomies.
[autosomal’s]
Autosomal trisomy
Trisomy 13
Patau syndrome (47 +13)
Trisomy 18
Edward syndrome (47 + 18)
Trisomy 21
Down syndrome (47 + 21)
1/10,000 births
[trisomy]
Edwards syndrome (47+18)
Average survival time: 2-4 months
[trisomy]
Edwards syndrome (47+18)
Affected infants small at birth grow slowly and are mentally retarded.
[trisomy]
Edwards syndrome (47+18)
Malformation of heart, hands and feet.
[trisomy]
Edwards syndrome (47+18)
For unknown reasons 80% of all trisomy 18 are female.
[trisomy]
Edwards (47+18)
Advanced maternal age is a risk factor.
[trisomy]
Edwards syndrome (47+18)
1/5,000births.
[trisomy]
Patau syndrome (47+13)
Lethal: mean survival time is at least 1 month.
[trisomy]
Patau syndrome (47+13)
Facial malformations, eye defects, extra fingers or toes, and large protruding heels.
[trisomy]
Patau syndrome (47+13)
Severe malformations of brain, nervous system, and heart.
[trisomy]
Patau syndrome (47+13)
Parental age only known risk factor.
[trisomy]
Patau syndrome (47+13)
First chromosomal abnormality discovered in humans (1959).
[trisomy]
Down syndrome (47+21)
1/700 live births.
[trisomy]
Down syndrome (47+21)
Leading cause of mental retardation and heartdefects in US.
[trisomy]
Down syndrome (47+21)
Wide flat skulls, skin folds in the corner of the eyes, spots on the irises, and thick-furrowed tongues.
[trisomy]
Down syndrome (47+21)
40% congenital heart defects.
[trisomy]
Down syndrome (47+21)
Features do not develop until after puberty.
[ktj syndrome]
Kinefelter’s syndrome
Affected individuals are male with low fertility and may have mental dysfunction.
[ktj syndrome]
Kinefelter’s syndrome
60% due to maternal nondisjunction.
[ktj syndrome]
Kinefelter’s syndrome
Other forms XXYY, XXXY and XXXXY.
[ktj syndrome]
Kinefelter’s syndrome
Females; short, wide chest; rudimentary ovaries; and abnormal sexual development.
[ktj syndrome]
Turner’s syndrome
Puffiness of hands and feet.
[ktj syndrome]
Turner syndrome
Abnormalities of the aorta.
[ktj syndrome]
Turner syndrome
No mental dysfunction.
[ktj syndrome]
Turner syndrome
Single X chromosome; two X chromosomes are required for normal female sexual development.
[ktj syndrome]
Turner syndrome
Complete absence of an X chromosome is lethal- (So, no Y monosomies).
[ktj syndrome]
Turner syndrome
Above average in height.
[ktj syndrome]
Jacob syndrome
No established link with possible antisocial behavior.
[ktj syndrome]
Jacob syndrome
