UNIT 5: Chromosomal Aberrations Flashcards
t/f: Chromosomal mutations is commonly known as chromosomal aberrations
true
these are variations from the wild-type condition in either chromosome structure or number
Chromosomal mutations
t/f: Chromosomal mutations arise spontaneously or induced by chemical or radiation mutagens
true
chromosomal abnormality: abnormal chromosome number, quantitative
Aneuploidy
2 types of chromosomal abnormalities
Aneuploidy
Structural
chromosomal abnormality: alteration, qualitative
Structural
4 variations in chromosome structure
Deletion
Duplication
Inversion
Translocation
2 types of Variation in Chromosome Number
Aneuploidy
Polyploidy
t/f: monosomics/trisomics/nullisomics/tetrasomics are under polyploidy
false, aneuploidy
3 categories of chromosome mutations
Chromosome rearrangements
Aneuploidy
Polyploidy
Category of chromosome mutation:
overall chromosome number is unaffected but large pieces of chromosomes move altering the chromosome structure
Chromosome Rearrangements
Category of chromosome mutation:
one or more individual chromosome pair has its number altered (either up or down) altering chromosome number
Aneuploidy
Category of chromosome mutation:
down syndrome, klinefelter, turners, 45, 47
Aneuploidy
Category of chromosome mutation:
humans with 3n, 4n, etc.
polyploidy
t/f: aneuploidy is better than polyploidy
true
Category of chromosome mutation:
one or more complete chromosome sets are added
Polyploidy
when a set of chromosomes do not properly separate leaving two sex cells with an extra chromosome or one less chromosome developing a chromosomal disorder
Nondisjunction
results when an error occurs during meiosis, specifically non disjunction.
aneuploidy
most often caused by error during cell division, mitosis and meiosis
chromosomal aberrations
a pair of homologous chromosomes has failed to separate or segregate at anaphase so that both chromosomes of the pair pass to the same daughter cell
nondisjunction
t/f: non disjunction occurs most commonly in mitosis
false, meiosis
t/f: nondisjuction in mitosis produces mosaic individual
true
t/f: structural chromosomal aberrations can result in an aneuploidy
true
when part or all of a chromosome is missing, turned upside down, duplicated, or attached to another chromosome
structural chromosomal aberrations
t/f: when structural chromosomal aberrations occur after meiosis, two copies or no copies is passed down ending up with monosomy or trisomy
true
when two or more different cell lines in one person and occurs after non disjunction in a mitotic cell division
mosaicism
t/f: mosaicism results in one line of cells with chromosomal aberration white other lines may stay unchanged
true
chromosomal mutation that results in the doubling of a segment of a chromosome
duplication
3 forms of duplication
1 Tandem Duplication
2 Reverse Duplication
3 Terminal Tandem Duplication
meaning of ISCN
International System for Human Cytogenomic Nomenclature (ISCN)
according to ISCN, dup means
duplication of parts of a chromosome
dup(17p12) causes ____ disease
charcot-marie-tooth type 1A
meaning of dup(17p12)
duplication of chromosome 17, region 1, band 2
when a part of chromosome is double
duplication
types of duplication
tandem duplication
displaced duplication
reverse duplication
type of duplication: one right after the other
ABCDEFGH -> ABCDEF [EF] GH
tandem duplication
type of duplication: goes to another place but still in the same chromosome
ABCDEFGH -> AB [EF] CD EFGH
Displaced duplication
type of duplication: where the duplicated region is inverted
ABCDEFGH -> ABCD[FE] EFGH
reverse duplication
t/f: individuals can only be homozygous for duplications
false, can be homozygous or heterozygous
when heterozygous for duplication, problems arise during ___ of meiosis and synapsis
prophase 1
when heterozygous for duplication, one duplicated region must ___ to allow synapsis to occur
loop out
due to ___, duplications may have significant effects on an individuals’s phenotype
unbalanced gene dosage
we are evolved to have ___ alleles for each gene
two alleles
t/f: duplications also allow new genes to be born with novel functions
true
t/f: when a gene duplicates the new duplicated gene cannot be free to mutate and evolve while the original gene continues carrying on normal functions allowing evolution to proceed with little risk to the individual
false, it can
duplication allowed fetal hemoglobin to evolve, making placental ___ reproduction possible
in utero reproduction
t/f: because of mutations, species are not evolving
false, they are evolving because of mutations
involves the loss of a segment of a chromosome
deletions
t/f: in deletions, deleted segment is only located in a specific site along the chromosome
false, may be located anywhere along the chromosome
t/f: breaks in chromosome for deletions may be caused by agents such as heat, ionizing radiation, viruses, transposable elements) or by errors in recombination
true
which molecular test is used for detecting copy number loss and copy number gains
CGH
t/f: chromosomal deletions may or may not span a centromere
true
if a deletion spans a centromere, it results to ____
acentric chromosome
3 types of deletions
terminal deletion
intercalary/interstitial deletion
microdeletion
type of deletion: a deletion that occurs towards the end of a chromosome
terminal deletion
type of deletion: a deletion that occurs from the interior of a chromosome
Intercalary/interstitial deletions
type of deletion: a relatively small amount of deletion (up to 5Mb that could include a dozen genes)
microdeletion
usually found in children with physical abnormalities.
microdeletion
a large amount of deletion in children would results in immediate ____ also called ____
abortion, miscarriage
the loss of a region or segment from a chromosome
chromosome deletions
ABCDEFGH -> ABCDGH
Chromosome Deletions
if the deletion is large enough, it can be detected in a karyotype as _____ chromosome
shortened chromosome
deletions also result in ____ during prophase 1 to allow alignment during synapsis
looping out
t/f: the effect of a deletion depends solely on what genetic information was deleted
true
t/f: deletions are lethal, and are completely symptomatic
false, others are completely asymptomatic
if the deleted region includes the centromere, the mutated chromosomes will ____ during mitosis or meiosis and are usually ___ by the cell during cell division
not segregate, lost
deletions are highly detrimental when an individual is ___ for the deletion
homozygous
t/f: homozygous for the deletion would be the complete absence of that genetic information
true
deletions in heterzygous individuals cause ____ like duplications
gene imbalance
difference between the gene imbalance cause by duplications and deletions in heterozygous
duplications: too much
deletions: not enough
t/f: recessive alleles does not express more readily when there are deletions
false, it is express more readily
according to ISCN, minus (-) is for ____ and del is for ____
minus (-) = chromosome deletions
del = deletions of a part of a chromosome
this results from a deletion of a number of pairs that is not evenly divisible by three
frameshift mutation
causes all of the codons occuring after the deletion to be read incorrectly during translation, producing altered or nonfunctional protein
frameshift mutation
a deletion that is evenly divisible by three is called ____
in frame deletion
what are the 3 major genetic disorders caused by deletions
- male infertility
- duchenne muscular dystrophy
- cystic fibrosis ( ΔF508)
deletion of part of the short arm of chromosome 5 results to ____
cri du chat syndrome
deletions in the SMN-encoding gene causes _______
spinal muscular atrophy
t/f: spinal muscular atrophy is the most common genetic cause of adult death
false, infant death
microdeletions are associated with conditions (3)
Angelman Syndrome
Prader-Willi syndrome
DiGeorge Syndrome
syndromes associated with microdeletions adn genomic imprinting
Angelman syndrome
prader-willi syndrome
t/f: same microdeletion can cause two different syndromes depending on which parent the deletion came from
true
human disorders caused by deletions: 5p-
cri du chat syndrome
human disorders caused by deletions: 13q-
retinoblastoma
human disorders caused by deletions: 11q-
wilms tumor
human disorders caused by deletions: 15q-
prader-willi syndrome
infants have catlike cry, some facial anomalies, severe mental retardation
cri du chat syndrome
kidney tumors, genital and urinary tract abnormalities
wilms tumor
cancer of the eye, increased risk of other cancer
retinoblastoma
infants: weak slow growth; children and adults: obesity, compulsive eating
prader-willi syndrome
deletion in the short arm of chromosome 5
cri du chat syndrome
cri du chat syndrome occurs in every __ out of 100,000 births
1
mentally retarded, with defects on facial development, gastrointestinal malformations, and abnormal throat structures
cri du chat syndrome
cry of the cat
cri du chat
deletions in the long arm of chromosome 15
prader-willi syndrome
prader willi syndrome occurs when there is deletions between the bands of ___ and ___ of chromosome 15
q 11 and q 13
affected infants of prader willi syndrome has ____ reflex
poor sucking reflex
by age ____, children of prader willi syndrome become compulsive eaters
5-6
poor sexual development in males, behavioral problems and mental retardation
prader willi syndrome
delayed development, problems with speech and balance, intellectual disability, and sometimes, seizures
angelman syndrome
t/f: people with angelman syndrome often smile and laugh frequently and have happy excitable personalities
true
in angelman syndrome, developmental delays begin between about ___ and ___ months of age
6 - 12 months
in angelman syndrome, seizures begin between ages ___ and __ years old
2-3 years old
t/f: people with angelman syndrome have short life span
false, they have close to a normal life span
t/f: angelman syndrome cannot be cured
true
in angelman syndrome, the loss of a gene called ____ is associated with light colored hair and fair skin
OCA2
the OCA2 gene is located on the segment of chromosome ___ that is often deleted in people with disorder
15
it is a chromosomal mutation that results when a segment of a chromosome is excised and then reintegrated in an orientation 180 degrees celsius from the original orientation
inversion
2 forms of inversion
pericentric inversion
paracentric inversion
according to ISCN,abbreviation “inv” means
inv = inversions
for inversions to happen, the DNA must break in ___ on either side of the inverted segment
two places
inversion that does not include the centromere
paracentric inversions
inversions that include the centromere
pericentric inversions
t/f: inversions played an active role in the evolution of humans
true
humans differ from chimps greatly in ____
inversions
in what chromosome does chimps and humans differ greatly in inversions, and what type of inversion
chromosome 4, pericentric inversion
karyotypic differences between humans and chimpanzees include ___ pericentric inversions
9 pericentric inversions
the breakpoints of the inversion that distinguishes human chromosome 4 (HSA4) from its chimpanzee counterpart were identified by ____ (___) and _______
flourescence in situ hybridization (FISH)
comparative sequence analysis
breakpoints at ____ and ___, do not disrupt the protein coding of a gene, although they occur in regions with an abundance of LINE and LTR-elements
HSA4p14 and 4q21.3
if an inversion breaks a gene in half, moving half of that gene to another part of the chromosome will render that gene _____
inactive
t/f: chromosome inversions usually do not cause detrimental effects
false, if the gene inverted was important, it will be
t/f: many genes are regulated based on their position on the chromosome
true
what do you call the effect where you change a gene’s position and it turn you change its regulation
position effect
individuals ____ for inversion require some super-funky loops in order to allow synapsis in meiosis
heterozygous
genes are regulated, two things may happen in position effect what are these two
- far from transcription factors
- close to transcription factors
there is a change in the position of chromosome segments and the gene sequences they contain
translocation
t/f: in translocation there is gain or loss of genetic material
false, there is none
2 kinds of translocation
intrachromosomal
interchromosomal
kind of translocation: change in position of a chromosome segment within the same chromosome
intrachromosomal
kind of translocation: transfer of a chromosome segment from one chromosome into a nonhomologous chromosome
interchromosomal
t/f: translocations are usually non homologous
true
according to ISCN, what is the meaning of t(A;B)(p1;q2)
t=translocation
A= chromosome A
B = chromosome B
p = short arm
q = long arm
numbers = regions, bands, and subbands
regions, bands, and sub bands are seen when staining the chromosome with a ____
staining dye
when DNA moves from one chromosome to another non homologous chromosome, a ____ has occurred
translocation
t/f: translocations may not occur in a single chromosome
false, it can also
translocation where DNA only moved in one direction
Nonreciprocal translocation
translocation where DNA is exchanged in both directions
reciprocal translocations
t/f: non reciprocal translocations are more common than reciprocal
false, reciprocal are more common
t/f: translocation is only between homologous chromosomes during meiosis
false, that is crossing over
t/f: chimps, orangutans and gorillas have 24 chromosomes
false, 48
t/f: translocations cause new linkage patterns thus changing how genes are inherited
true
t/f: translocations does not result in position effects
false, it results also
t/f: chromosome duplications often accompany translocations
false, chromosome deletions
2 types of interchromosomal translocation
reciprocal
non reciprocal
type of interchromosomal translocation: exchange of segments between two chromosomes
reciprocal
type of interchromosomal translocation: transfer of segment in one direction from one chromosome to another
non-reciprocal
when the short or long arms of same chromosome join at centromere and creates two copies of a large genetic region
isochromes
shows characteristic mirror image appearance of banding patterns extending in both directions from centromere
isochromes
joining of centromere occuring between chromosomes that have tiny short arms (acrocentrics)
robertsonian translocation
t/f: in robersonian translocation, there is no obvious lost in genetic information because the short arms contain repeated rRNA genes
true
involves reciprocal translocation between the long arm of chromosome 22 and chromosome 9
chronic myelogenous leukemia
transition of c-abl within the bcr
chronic myelogenous leukemia
results to uncontrolled replication of myeloblasts
chronic myelogenous leukemia
PML RARA is what type of gene
translocation gene
common disease in africa, virus induced tumor; malignant B cells secrete antibodies
burkitt’s lymphoma
involves reciprocal translocation between chromosome 8 and 14 and activation of c-myc
burkitt’s lymphoma
organism or cell has one or exact multiple of complete set(s) of chromosomes
euploidy
irregular distribution of sister chromatids during mitosis or of homologus chromosomes during meiosis
nondisjunction
type of aneuploidy: both members of a homologous pair are lost (46 to 44 or 2n -2)
nullisomy
4 types of aneuploidy
nullisomy
monosomy
trisomy
tetrasomy
type of aneuploidy: one chromosome is lost (46 to 45 or 2n - 1)
monosomy
type of aneuploidy: one chromosome is gained (2n + 1)
trisomy
type of aneuploidy: involves an extra chromosome pair (2n + 2)
tetrasomy
t/f: it is not possible for an individual to have multiple instances of aneuploidy and still have normal chromosome number
true
2n + 1 + 1
double trisomic
t/f: trisomy of the X chromosome cannot be tolerated in females
false, it is tolerated well
t/f: Y aneuploids are viable
true
___% of all successful concenptions spontaneously abort (miscarry)
30%
__% of these miscarried fetuses ahve chromosome mutations
50%
in humans, only __% of aneuploids survive to birth
3%
in mice, ___% of all conceptions are aneuploid
2%
t/f: most human aneuploids have X or Y chromosome aneuploidy
true
occurs ~1 in 25,000 to 50,000 live briths, mental retardation adn characteristic physical alternations, many have normal life expectancy
trisomy 8
t/f: trisomy 21 is tolerated better because it a small chromosome with fewer genes
true
syndrome: trisomic 21
down syndrome
syndrome: trisomic 13
patau
syndrome: trisomic 18
edwards
syndrome: XO, monosomic
turner
syndrome: trisomic XYY
normal
syndrome: XXY, XXYY,XXXY
klinefelter
wide skull flat back, epicanthic fold, iris spots, furrowed and protrudign tongue, congenital heart defects
trisomy 21
cleft lip and palate, small eyes, polydactyl (extra fingers and toes), mental and developmental retardation, severe malformation of the brain and nervous system
trisomy 13
most affected infants of trisomy 13 die before the age of ____
three months
life expectancy of edward syndrom
2-4 months
life expectancy of trisomy 13
50% die within first month, 95% three years
life expectancy of trisomy 8
may be normal life expectancy
t/f: males are mostly affected by edwards syndrome
false, females
multple congenital malformations, clenched fists, elongated skill, low set ears, retardations
edwards
leading risk factor for autosomal trisomy
maternal age
t/f: the integrity of primary oocytes increases as the women age
false, decreases
t/f: as a woman age, maternal selection becomes less effective
true
short and wide chested, webbed neck, underdeveloped breasts and rudimentary ovaries, absence of barr body, color blindness, narrowing of aorta
turner syndrome
t/f: klinefeltersyndrome features do not develop until puberty
true
males with poor sexual development, very low fertility, breast development
klinefelter syndrome
above average height, suffered personality disorders, below normal intelligence, violent criminal behavior
47, XYY
t/f: Y chromosome is essential for suvival
false, X chromosome
getting two chromsomes from one parent
uniparental disomy
cell is conceived trisomatic but loses a chromosome early on in development
uniparental disomy
chromosome lost came from the nondisjunctive parent, teh other two came from one parent
uniparental disomy
polyploidy is common in ____ and is the major driving force behind its speciation
plants
two types of polyploidy
autopolyploidy
allopolyploidy
type of polyploidy: all sets of chromosomes are from a single species
autopolyploidy
type of polyploidy: when polyploidy represents a hybridization between specieies with chromosome sets coming from different cells
allopolyploidy
t/f: allopolyploids are sterile and cannto cross fertilize but plants can
true
most common form of polyploidy
triploidy
(69, XXY), (69,XXX), (69,XYY)
triploidy
life expectancy of triploid infants
within a month
DNA duplication but no cell division is called
endomitosis
endomitosis results to ____
tetraploidy
___ of DNA and histones causes nucleosomes to pack tightly together
Methylation
___ results in loose packing of nucleosomes
Histone acetylation
Gene mutation/Chromosomal mutations:
alteration of the nucleotide of sequence of a gene
Gene mutation
