Unit 5: Chromosome Aberrations Flashcards
Chromosomal mutations are commonly known as ____________?
Chromosomal aberrations
Chromosomal aberrations are essentially abnormalities in:
A. Chromosome number
B. Chromosome structure
C. Both are correct
D. None are correct
C
Which is false about chromosomal aberrations?
A. Arise spontaneously
B. May be chemically induced
C. May be caused by radiation mutagens
D. There are no false statements
D
True or False?
Chromosomal abnormalities give rise to specific physical symptoms, however, these vary in different individuals.
True
Condition wherein affected individual has a total of three sets of each chromosomes (a total of 69 chromosomes)
Triploidy
Condition wherein affected individual has a total of four sets of each chromosomes (a total of 92 chromosomes)
Tetraploidy
Which of the following has more harmful effects?
Trisomy or Monosomy
Monosomy
Variation in _________ include:
Deletion, Duplication, Inversion, Translocation
Chromosome Structure
Type of Aberration
Occur due to loss or rearrangement of the location of the genetic material.
Structural aberrations
Variation in Chromosome structure can occur during the following, except for:
A. Mitosis
B. Meiosis
C. Fertilization
D. All are correct
A
Variation in _________ include:
Aneuploidy
Polyploidy
Chromosome number
It involves the loss of a segment of a chromosome.
Note: May occur anywhere along the chromosome
Deletion
Type of Aberration
Are usually caused by failure in chromosome division
Numerical aberrations
Deletion starts in ________ of chromosomes that may be caused by agents (heat, radiation, viruses, transposable elements) or errors in recombination.
Breaks
Deletions are generally ________ (harmless/harmful) to the affected organism.
Harmful
True or False?
The smaller the deletion, the greater the harm it can cause to an individual.
False
True or False?
Chromosomal deletions can produce acentric chromosomes if the deletion spans over the centromere.
True
What is the syndrome?
Infants have a catlike cry, some facial anomalies, severe mental retardation. Gastrointestinal malformation and abnormal throat structures can also manifest.
Note: Deletion of a portion of the short arm on chromosome 5 (5p-)
Note: Occur in 1 out of 100,000 births.
Cri du chat syndrome
Cri du chat syndrome is a/an _______________ (terminal/interstitial) deletion.
terminal
What does “Cri du chat” translate to?
Cry of the cat
Which of the following bands are not usually deleted in Cri du chat syndrome?
A. 5p15.1
B. 5p15.2
C. 5p15.3
D. All of the above are deleted
A
What is the syndrome?
Rare kidney cancer primarily affecting children; Kidney cells do not mature; Kidney tumors, genital and urinary tract abnormalities
Note: Deletion of a portion of the long arm on chromosome 11 (11q-)
Wilms tumor
What is the syndrome?
Cancer of the eye, increased risk of other cancers; Affecting the nerve cells of the retina
Note: Deletion of a portion of the long arm on chromosome 13 (13q-)
Retinoblastoma
What is the syndrome?
Complex genetic condition affecting many parts of the body. In infants, it causes slow growth. In children and adults, it causes obesity and compulsive eating. Affects the development and function of hypothalamus
Also includes poor sucking reflex, poor sexual development in males, behavioral problems and mental retardation.
Note: Deletion of a portion of the long arm on chromosome 15 (15q-)
Prader-Willi syndrome
Which of the following bands are deleted in Prader-Willi syndrome?
A. 15q11.2-13
B. 15q10.4-14
C. 12q2-3.2
D. 15p2-3.2
A
Chromosomal mutation that results in the doubling of a segment of a chromosome.
Duplication
Form of Chromosome Duplication
Duplicated segment is present in the same orientation immediately adjacent to the original segment of the chromosome.
Note: Able to produce even more copies of the duplicated region
Tandem duplication
Form of Chromosome Duplication
Duplicated segment is present in the opposite orientation (genes are inverted).
Note: May form a loop due to the inverted portion pairing with the normal homologous chromosome segment present on the same arm. May cause dicentric chromatid bridge (anaphase I).
Reverse duplication
Form of Chromosome Duplication
Duplicated segment is present in the same orientation immediately adjacent to the original segment of the chromosome occuring at the end of the chromosome.
Terminal tandem duplication
Chromosomal mutation that results when a segment of a chromosome is excised and then reintegrated in an orientation 180° from the original orientation.
Inversion
Form of Chromosome Inversion
Inversion involving the centromere (chromosome’’s restriction point)
Pericentric Inversion
Form of Chromosome Inversion
Inversion not involving the centromere (chromosome’’s restriction point)
Paracentric Inversion
Chromosomal mutation wherein there is a change in position of chromosome segments and he gene sequences they contain.
Note: No gain or loss of genetic material (unless in interchromosomal translocation)
Translocation
Form of Chromosome Translocation
Change in position of a chromosome segment within same chromosome
Intrachromosomal Translocation
Form of Chromosome Translocation
Transfer of a chromosome segment from one chromosome into a nonhomologous chromosome
Interchromosomal Translocation
Type of Interchromosomal Translocation
Transfer of segment in one direction from on chromosome to another
Non-reciprocal
Type of Interchromosomal Translocation
Exchange of segments between two chromosomes
Reciprocal
Intrachromosomal translocation are:
A. Always reciprocal
B. Always non-reciprocal
C. Can be reciprocal or non-reciprocal
B
Interchromosomal translocation are:
A. Always reciprocal
B. Always non-reciprocal
C. Can be reciprocal or non-reciprocal
C
Two short arms and/or two long arms of the same chromosome join at the centromere.
Note: Creates two copies of a large genetic region. Show a characteristic mirror image appearance of banding patterns extending from centromere.
Isochromosomes
Form of Chromosome Translocation
One of the most common types of chromosomal translocation. Special cases of the joining of acrocentric chromosomes at their centromeres. Forms a long and very recognizable product.
Note: No obvious lost in genetic information because short arms contain only repeated rRNA genes.
Robertsonian translocation
In Robertsonian translocation, the _____ (p arms/q arms) are usually lost.
p arms
An abnormal chromosome produced by translocation of parts of the long arms of chromosomes 9 and 22. Transition of c-abl within the bcr.
Philadelphia chromosome
True or False?
In normal chromosomes, the BCR gene is located in chromosome 22, while the ABL gene is located in chromosome 9.
False
Gene (present in Philadelphia chromosome) that arises from the translocation of chromosome 22 and 9. When transcribed, produces a chimeric mRNA that generate fusion protein with tyrosine kinase activity. Alter cell cycle control resulting in uncontrolled cell proliferation.
BCR-ABL 1
Common disease in Africa that causes a virus-induced tumor affecting malignant B lymphocytes that secrete antibodies. Involves reciprocal translocation between chromosome 8 and 14.
Burkitt’s Lymphoma
What gene is activated in Burkitt’s Lymphoma and causes uncontrolled growth and cell proliferation.
c-myc
What virus is linked to Burkitt’s Lymphoma?
Epstein-Barr virus (EBV)
True or False?
The myc gene is located in chromosome 8, while the immunoglobulin heavy chain promoter gene is located in chromosome 14.
True
Normal cellular genes that regulate cell proliferation and differentiation that can become oncogenes. Example: c-myc gene
Proto-oncogenes
Condition wherein an organism/cell has one or exact multiple of complete sets of chromosomes
Euploidy
Chromosome mutations may occur in
A. Variation in the number of individual chromosomes
B. Variation in complete sets of chromosomes
C. Both are correct
D. None of the above
C
One or several chromosomes are lost from or added to the normal set of chromosomes.
Aneuploidy
Irregular distribution of sister chromatids during mitosis or of homologous chromosomes during meiosis.; Error in meiosis in which homologous chromosomes fail to separate during anaphase.
Nondisjunction
Form of Aneuploidy
Involves a loss of one homologous pair; 2N-2
Nullisomy
Form of Aneuploidy
Involves a loss of a single chromosome; 2N-1
Monosomy
Form of Aneuploidy
Involves an additional extra chromosome; 2N+1
Trisomy
Form of Aneuploidy
Involves an extra chromosome pair; 2N+2
Tetrasomy
Condition named as mongolism (but not used anymore). Occurs when there are three copies of chromosome 21.
Phenotypic features:
-Wide skull that is flat at the back
-Eyelids have an epicanthic fold
-Iris contains spots
-Tongue are furrowed and protruding
-Physical, behavioral, and mental development are retarded
-Some have congenital heart defects
Down Syndrome (Trisomy 21)
Occurs when there are three copies of chromosome 13.
Phenotypic features:
-Cleft lip and palate
-Small eyes
-Polydactyly (extra fingers and/or toes)
-Mental and developmental retardation
-Severe malformations of brain and nervous system
Patau Syndrome (Trisomy 13)
Among the syndromes below, which will have the highest rate of survivability in infants?
A. Patau Syndrome
B. Down Syndrome
C. Edward Syndrome
B
Occurs when there are three copies of chromosome 18. Most affected infants are females.
Phenotypic features:
-Multiple congenital malformations affecting almost -every organ system
-Clenched fists
-Elongated Skull
-Low-set malformed ears
-Mental and developmental retardation
Edward Syndrome (Trisomy 18)
What is the leading risk factor for trisomy?
Maternal age
What is not a reason why maternal age is the leading risk factor of autosomal trisomy?
A. Integrity of primary oocytes degreases with age
B. Paternal selection becomes less effective
C. Maternal selection becomes less effective
D. All are correct
B
True or False?
Complete absence of X chromosome in the absence or presence of Y chromosome is not always lethal
False
Monosomy for the X chromosome
Phenotypic features:
-Short and wide-chested
-Extra folds of skin on the neck
-Underdeveloped breasts
-Rudimentary ovaries
-Absence of Barr Body
-Color Blindness
-Narrowing of Aorta
Turner Syndrome (45, X)
Phenotypic features do not develop until puberty. Interfere with testosterone production.
Phenotypic features:
-Poor sexual development
-Very low fertility
-With breast development
Klinefelter Syndrome (47, XXY)
True or False?
Only females can have Klinefelter Syndrome.
False
Aside from the (47, XXY), the following are forms of Klinefelter Syndrome, except for:
A. (48, XXYY)
B. (48, XXXY)
C. (47, XYY)
D. (49, XXXXY)
E. All are forms of Klinefelter Syndrome
C
Phenotypic features:
-Above average height
-Suffered personality disorders
-Below normal intelligence
-Violent criminal behavior
XYY Syndrome (47, XYY)
True or False?
Y chromosome is essential for survival. It has a role in normal development.
False
True or False?
Addition or extra copies of either sex chromosome interferes with normal development and causes both physical and mental problems.
True
Abnormalities in the number of haploid chromosomal sets can arise in the following ways, except for:
A. Errors in meiosis during gamete formation
B. Events in fertilization
C. Errors in mitosis following fertilization
D. Errors in picking your partner
D
True or False?
Polyploidy involves variations from the normal state in the number of complete sets of chromosomes.
True
A haploid set of chromosomes contain how many chromosomes?
23
A diploid set of chromosomes contain how many chromosomes?
46
Deviation from the normal diploid set of chromosomes is called _________?
Polyploidy
Most common form of polyploidy. 3 sets of the haploid number of chromosomes (n=23) e.g. 69, XXY. Triploid infants have only limited survival and most die in a month.
Triploidy
These are forms of triploidy, except for:
A. (69, XXY)
B. (69, XXX)
C. (69, XYY)
D. All are forms of triploidy
D
The following are origins of triploidy, except for:
A. Two haploid sperms fertilize a diploid egg
B. One haploid sperm fertilizes a diploid egg
C. One diploid sperm fertilizes a haploid egg
D. Two haploid sperms fertilizes a haploid egg
E. All are origins of triploidy
A
Normal fertilization occurs when a ___________ (haploid/diploid) sperm fertilizes a __________ (haploid/diploid) egg.
A. diploid, diploid
B. haploid, haploid
C. diploid, haploid
D. haploid, diploid
B
Percentage of triploid that originates from two haploid sperms and one haploid egg.
66
Percentage of triploid that originates from one haploid sperm and one diploid egg.
10
Percentage of triploid that originates from one diploid sperm and one haploid egg.
24
DNA duplication and chromosomal division has occurred but was not followed by cellular and nuclear division.
Note: Causes Tetraploidy.
Endomitosis
