CYTOGEN Flashcards
refers to differences between members of the same species or those of different species
GENETIC VARIATION
are substantial changes in the chromosome structure
Chromosomal Aberrations
primary ways in which the structure of chromosomes can be altered
Changes in total Amount of Genetic Information
Rearrangement
Decrease in Genetic Information
Deficiencies/ Deletions
increase in Genetic Information
Duplications & Insertions
Rearrangement of Genetic Information
Inversions, Translocations
– involve loss of material from a single chromosome. The effects are typically severe
since there is a loss of genetic material
DELETION
-Mis-division of the centromere
DELETION
-Deletions do ____________ because the DNA is gone (degraded)
not revert
It involves a single break and the terminal part of the chromosome is lost
Terminal Deletion
Can occur due to errors in cell division or because of environmental factors like radiation, chemicals, or viral infection
Terminal Deletion
resulting from terminal deletion of
part of the short arm of chromosome 5
Cri-du-chat syndrome (OMIM 123450)
a terminal deletion on the short arm of chromosome 4
Wolf-Hirschhorn Syndrome (OMIM 194190)
Deletion that does not involve the terminal parts of a chromosome
Interstitial Deletion
causes symptoms including microcephaly, round face, hypertelorism, epicanthal folds, low-set ears, and
micrognathia.
Cri-du-chat syndrome (OMIM 123450)
Causes Severe psychomotor and mental retardation
Cri-du-chat syndrome (OMIM 123450)
resulting from an interstitial deletion on chromosome 22, leading to a wide range of clinical features, including heart defects, immune system abnormalities, developmental delays, and characteristic facial features
DiGeorge Syndrome (OMIM 188400)
A deletion in one allele of a homozygous wildtype organism may give a ______ phenotype
normal
deletion in the wild-type allele of a heterozygote would produce a ________ phenotype.
mutant
Deletion of the __________ results in an ___________ chromosome that is lost, usually with serious or lethal consequences.
centromere, acentric
result from doubling of chromosomal segments, and occur in a range of
sizes and locations
DUPLICATION
duplications are adjacent to each other
Tandem duplications
duplications result in genes arranged in the opposite order of the original.
Reverse tandem duplications
Tandem duplication at the end of a chromosome is a ______________________
terminal tandem duplication
duplications are not adjacent to each other
non-tandem duplications
Drosophila eye shape allele, _________, that reduces the number of eye facets, giving the eye a slit-like rather than oval appearance
Bar
The lack of muscle, a high arch, and claw toes are signs of this genetic disease.
Charcot–Marie–Tooth Disease
Charcot–Marie–Tooth Disease is caused by duplication of the gene encoding ________________________
on chromosome ___.
peripheral myelin protein 22 (PMP22), 17
Results when a chromosome segment excises and reintegrates oriented 180 degrees from the original orientation
INVERSION
There is usually no risk for problems to an individual if the inversion is of __________________
familial origin
Most Analyses of inversions use ______________ inversions- diploids in which one chromosome has the standard sequence and one carries the inversion
heterozygous
inversion that includes the centromere
Pericentric Inversion
Inversion that does not include the centromere
Paracentric Inversion
Crossing-over within the inversion loop of a paracentric inversion connects homologous
centromeres in a __________________ while also producing an ____________________—a fragment without a centromere.
dicentric bridge, acentric fragment
As the chromosomes separate in _________________, the centromeres remain linked by the
bridge, which orients the centromeres so that the ______________ chromatids lie farthest apart.
anaphase I, noncrossover
Tension eventually breaks the bridge, forming two chromosomes with _________________________
terminal deletions
The gametes containing such deleted chromosomes may be inviable but, even if viable, the
___________ that they eventually form are inviable.
zygotes
CONSEQUENCIES OF CHROMOSOME INVERSION IN HUMANS:
lowered fertility due to production of unbalanced gametes
occurs when a segment of one chromosome is transferred to another chromosome
Translocation
Involves the rearrangement of parts between non-homologous chromosomes
Translocation
There are two main types of Translocation:
- Reciprocal (Balanced) Translocation
2.Robertsonian (unbalanced) Translocation
in _____________ two non/homologues chromosomes exchanged genetic material
reciprocal translocations
-the transfer of genetic material occurs in only one direction
-are associated with phenotypic abnormalities or even lethality
ROBERTSONIAN TRANSLOCATIONS
- In this condition, the majority of chromosome _____ is attached to chromosome ____
- The individual would have three copies of genes found on a large segment of chromosome 21; Therefore, they exhibit the characteristic of ___________________
21, 14, Down Syndrome
Breaks occur at the extreme ends of the ________ arms of two non-homologous acrocentric chromosomes.
short
Robertsonian Translocations are confined to chromosomes _____________ (the acrocentric
chromosomes)
13, 14, 15, 21, 22
- Most human malignant tumors have _________________________
- Most common are _________________
chromosomal mutations, translocations
is a type of non-Hodgkin lymphoma.
It develops when the body makes abnormal B-lymphocytes – the lymphoma cells. (Blymphocytes are white blood cells that fight infection)
Follicular Lymphoma
a structure where a chromosome has lost one of its arms, and the replacement arm is
an exact mirror image of the remaining arm
ISOCHROME
a structure where a chromosome has lost one of its arms, and the replacement arm is
an exact mirror image of the remaining arm
ISOCHROMES
development disorder that affects any parts of the body
- Characterized by extremely weak muscle tone, in in fancy and early childhood intellectual disability, distinctive facial features, sparse hair, areas of unusual skin features, and other birth defects
- extra isochromosome 12p
Pallister-Killian mosaic syndrome
Transfer of genetic material from Chromosome 14 to 18 in the Bcl2 terminal
Follicular Lymphoma
Transfer of genetic material myc gene from Chromosome 8 to 14 .
Burkitt Lymphoma
increased immunoglobin promotter
Burkitt Lymphoma
organisms which contain balanced ser or sets of chromosomes in any number
Euploidy
have a single basic set of chromosomes
Monoploidy
organisms with more than two genomes
Polyploid
most seedless fruits are ____________
Triploid
Diploid organisms which are missing one chromosome of a single pair are monosomic with the genomic formula 2n-1
Monosomy
can be either due to the loss of one or more chromosomes (hypoploidy) or due to addition of one or more chromosomes to the complete
chromosome set (hyperploidy)
Aneuploidy
An organism which has lost a chromosome pair is a nullosomic. The nullosomic organism has the genomic formula (2n–2).
Nullisomy
are those diploid organisms which have an extra chromosome (2n +1)
Trisomics
The diploid organisms having two extra chromosomes
Tetrasomy
Known as Trisomy 21
Down Syndrome
Down’s syndrome is named after the physician _______________________ who first described this genetic defect in 1866 and it was formally called ___________ or
_______________________.
J.Langdon Down, mongolism, mongolian idiocy
Known as Trisomy 18
Edward’s Syndrome
Known as Trisomy 13
Patau’s Syndrome
It is characterized by multiple malformations, primarily low-set ears; small
receding lower jaw; flexed and clenched fingers; cardiac malformations; and
various deformaties of skull, face and feet. Harelip and cleft palate often occurs.
Death takes place around 3 to 4 months of age.
Edward’s Syndrome
Individuals with ________________ appear to be markedly mentally retarded; have
sloping forehead, harelip and cleft palate. Polydactyly (both hands and feet) is
almost always present; the hands and feet are deformed. Cardiac and various
internal defects (of kidney, colon, small intestine) are common
Patau syndrome
Known as monosomy 45, X
Turner Syndrome
Known as 47, XXY
Klinefelter’s Syndrome
Known as Supermale; 47, XYY
XYY Syndrome
Known as Superfemale; 47, XXX)
XXX Syndrome
Gonadala dysgenesis, primary amenorrhoea
Average intelligence, short webbed neck (pterygium colli); low posterior
hairline; broad/shield chest; palms and feet edema (newborns)
Turner Syndrome
Tall stature; average intelligence; male psychosocial orientation;
hypoplastic testes, cryptochism; sterility- azoospermia; gynecomastia
(enlargement of breast in male)
Klinefelter’s Syndrome
