(M) Abrnormalities in Chromosomes Flashcards
senior-based transes
Changes resulting in a visible alteration of the
chromosome such as misrepair of broken bones, improper recombination or erroneous segregation during cell division can cause?
abnormalities
any exact multiple of the haploid
number of chromosomes (23) is called
euploid
T or F. Chromosome abnormalities lead to visible changes of the chromosomes
T
chromosome complements that are not exact multiples of 23
aneuploidy
T or F. Nondisjunction occurs when a HOMOLOGOUS pair of chromosome fails to disjoin or separate during cell division
T
identify each phase
1 is meiosis 1
2 is meiosis 2
3 is fertilization
4 is zygote
Nondisjunction during meiosis 2 produces daughter cells:
2 monosomic, 1 normal, and 1 no chromosome complement
if nondisjunction occus during meiosis 1, the meiosis 2 will produce?
2 daughter cells with 2 chromosomes
identify zygotes
2 zygotes with trisomy and 2 zygotes
with monosomy
identify zygotes
2 normal zygotes, 1 trisomic, and 1 monosomic zygote
T or F. A monosomic zygote is produced when there’s an extra chromosome.
F (2n-1 means there’s one less chromosome)
What phase does nondisjunction occurs?
1 and 2
what does it mean to have an extra chromosome (2n+1)?
Trisomic k beh
if nondisjunction occurs in meiosis 2, and
the daughter cells undergo fertilization, what you are going to produce are?
2 normal zygotes, 1 trisomic zygote, and 1 monosomic zygote (2:1:1)
Try to imagine what are the zygotes you will produce
If the nondisjunction occurs during meiosis 1 palang, one daughter cell will have an extra
chromosome and one with no chromosome complement
2 zygotes with trisomy and 2 zygotes
with monosomy
Identify what’s wrong with this
Oogenium -> primary spermatocyte -> 1 secondary oocyte and first polar body -> ootid -> 1 ova and 2 polar body
first correction: primary spermatocy should be primary oocyte
second correction: it will produce one mature egg cell and 3 POLAR bodies
just checking if familiar ka sa process ng gametogenesis
failure of the chromosomes to disjoin and pass to opposite poles
Meiotic Nondisjunction
T or F. 75% of meiotic nondisjuction occurs in OOGENESIS, where the probability of nondisjunction increases with maternal age
T
Almost how many % of meiotic nondisjunction occur in the first meiotic division?
80%
T or F. As men age, they have a higher likelihood of passing on genetic mutations to their offspring
T (4-5x increase mutation rate during
spermatogenesis because more cell division occur in the formation of sperm compared to oogenesis)
T or F. Babies who are born with younger father are prone to develop mendelian disorders due to a single gene mutation of large effects.
F (elderly father)
T or F. Increasing maternal age is associated with higher rate of mutation for Mendelian disorders during oogenesis in women.
F (increased naman ang nondisjunction)
What do u call when one homologous chromosome (meiosis) or chromatid (mitosis) lags behind and is left outside of the nucleus
anaphase lag
When chromosome/chromatid is lost, the gamete will fertilize and produce?
one normal cell and one monosomic cell
T or F. MONOSOMY involving an autosome generally represents loss of too much genetic materials to allow live birth or even embryogenesis, but a number of autosomal TRISOMIES do allow survival.
T
Anaphase Lag
The sister chromatids do not properly separate from each due to
Improper spindle formation
Anaphase Lag
During what phase will the chromatids will be left out of the cell membrane when the daughter chromosomes are formed?
Telophase
What is the chromosome that will be produced at the anaphase gap?
One will have monosomy and one will have a normal chromosome complement
T or F. The nomenclature of Chromosomes is described according to the IS for Human Genetic Nomenclature
F (Human Cytogenetic Nomenclature)
What describes the chromosomal
complement of an individual
Karyotype
T or F. In a karyotype, the total chromosome number is listed first,
followed by the sex chromosomes, and numerical and structural abnormalities and band location in DESCENDING order
F (ascend)
46,XX
babae
46,XY
bading
standard arrangement of a photographed or imaged stained metaphase spread in which the chromosome pairs are arranged in order of decreasing length
Karyotype
Part of a karyotype except:
A. Total number of chromosomes
B. Instertitial complement
C. Sex chromosome complement
D. Information on the Abnormality
B (imbento ko lang ‘ya)
the q arm stands for
long arm
the p arm stands for
short arm
when abnormalities occur after conception
mosaicism
i/iso
isochromosome
what does (-) and (+) mean
loss and gain
what does (r) mean
ring chromosome
what does (rcp) mean
reciprocal
what does (rob) mean
robertsonian translocation
identify the nomenclature
69,XXX/ 69,XXY/ 69,XYY
triploidy
identify the nomenclature
47,XX/XY, +21
trisonomy
identify the nomenclature
45,X
monosomy
identify the nomenclature
47,XXX/ 46,XX
mosaicism (1 normal and 1 that is produced after the nondisjunction; 1 trisomy, and 1 population of normal
cells)
1 egg, 3 sperms ang nag fertilize
gangbang eme Quadriploidy
Another way of diagnosing the numerical
abnormality is by?
FISH (fluorescent in situ
hybridization)
T or F. In the SISS method, they are using labeled probes in order to identify the no. of chromosomes present in a cell
F (FISH)
Identify Structural Abnormality
Deletion
a normal female with a deletion in chromosome 4 located in the short arm at region 1 and band 5
A. 46,XX,del(4)(p15)
B. 47,XX,del(4)(p155)
C. 45,XX,del(4)(p15)
D. 46,XX,del(1)(p15)
A
involves 2 breaks and the segment in between the breaks get detached and lost during cell division; however, the distal segments will reattach
insterstitial deletion
In the insterstitial deletion, what will reattach?
the distal segments and the chromosome fragment that was detached is lost during cell division
T or F. Instertitial deletion is also known to have one break in the chromosome
F (terminal)
in this deletion, the chromosome segment that is distal to the break get detached and do not reattach but is lost during cell division
terminal deletion
This 46,XY,inv(9)(p11q21.1) is one example of?
inversion
T or F. 46,XY,inv(9)(p11q21.1)
There are two breaks in the chromosome
arm
T
Inversion allows breaks occur in
both short and long arms and includes the centromere in the inverted segment
pericentric inversion
a normal female with a duplicated region at the long arm region 2, band 2 up to region 2, band 5
A. 46,XX,dup(1)(q22q255)
B. 46,XX,dup(1)(q22q225)
C. 46,XX,dup(1)(q22q25)
C
This inversion involves both arms and centromere
pericentric inversion
This inversion occurs only in the same arm, involves only one arm
Paracentric inversion
What number is the chromosome?
46,XY,inv(9)(p11q21.1)
9
What is the subband of petite?
46,XY,inv(9)(p11q21.1)
wala
This 46,XX,dup(1)(q22q25) is an example of?
duplication
in here, a semi-colon is used when 2 chromosomes are involved
translocation
segments of 2 different chromosomes switched places for a?
balanced tranlocation or simply translocation
chromosome has breaks in both the long and short arm
ring chromosome
when distal regions break, the remaining segments become what to form a ring structure?
STICKY
T or F. In ring chromosome, the detached fragments are recovered during cell division, hence a gain of genetic material
F (lost; loss)
Is this normal?
45,XY,r(9)(p12q21)
Abnormal male
46,XY,r(9)(p12q21
A. chromosome 9 at the short arm, region 1, band 2 and the long arm, region 2, band 1
B.chromosome 9 at the short arm, region 1, band 1 and the long arm, region 2, band 1
C. chromosome 46 at the short arm, region 9, band 1 and the long arm, region 2, band 1
A
T or F. A semi-colon can be used when only one chromosome is involved.
F
there is no loss of genetic information as there is only a transfer of segments at other regions
insertion
if a distal fragment is detached, as long as it reattaches to a proximal arm, then there is no loss of genetic information
insertion
Robertsonian translocation/centric fusion usually occurs in acrocentric chromosomes (centromeres are near the end)
derivative
This is an 46,XX,ins(2)(p13q21q31) of?
insertion
T or F. the 3 breakpoints fuse and a region of the short arm is lost while the long arms fuse
45,XY,der(14;21)(q10;q10)
F (2 breakpoints)
T or F. monosomy 14 is formed where chromosome 21 joined with chromosome 14 to make a single chromosome—the centromere belongs to chromosome 21 hence chromosome 21 is lost
45,XY,der(14;21)(q10;q10)
F (c14 is lost)
T or F. The patient is still phenotypically normal considering that the segments lost only contain small amounts of rRNA so it doesn’t affect the function of it however, future offspring may have abnormalities because of the extra chromosome 21 located in chromosome 14
45,XY,der(14;21)(q10;q10)
T
identify chromosomal abnormality
Trisomy 21
how many probes is shown?
3
identify
Top: paracentric inversion
Bottom: pericentric inversion
- 46 chrom, male, inversion in chromosome 11
- the break is in both arms. First is in short arm, region 1, band 1, and second is in short arm region 1,
band 5 - Then, the region between the two
breakpoints detaches, then flips upside down (180 degrees), and then reattaches.
Hence, this is a?
paracentric inversion
There is a breakpoint/deletion in both regions and the fragment between the two regions is deleted and is lost; then chromosome reattaches. Hence, this is an?
interstitial deletion.
T or F. Terminal deletion only has 2 loci.
F (1)
- 46 chrom
- male
- deletion in chromosome 4, short arm, region 1, band 6, sub band 3
- break gets detached and is lost
hence this is a?
terminal deletion
- 46 chrom
- male
- inversion in chromosome 11, the
break is in both arms - the region between the two breakpoints detaches, then flips upside down (180 degrees), and then reattaches.
Hence, this is?
paracentric inversion
The two breaks occur in the same arm and it does not involve the centromere
paracentric inversion
Karyotype: 46 chrom, female, insertion in chromosome 2 involving short arm, region 1, band 3, long arm, region 2, band 1, and long arm, region 3, band 1. The segment between the breakpoint q21 and q31 was inserted into the breakpoint of p13.
46,XX,ins(2)(p13q21q31)
Create karyotype
46 chrom, male, ring chromosome formation in chromosome 7. Two breakpoints are present, one in short arm, region 2, band 2, and another one in long arm, region 3, band 6.
46,XY,r(7)(p22q36)
The two chromosomes involved both have
breakpoints which swap positions with each other. Thus, this is a?
balance reciprocal translocation
identify
Centric fusion: Robertsonian
sually occurs in acrocentric
chromosomes – chromosomes which usually have their centromeres near the end of the chromosome.
Robertsonian translocation
or centric fusion
still considered as a balanced carrier
because they say that this part of the acrocentric chromosome (the lost part) only contains ribosomal RNA, and they are so plentiful that even though some of it is lost, it still does not affect the function of ribosomal RNA. The patient
is considered as
phenotypically normal
46,XX,der(14;21) (q10;q10), +21
What does the 14;21 indicate?
Robertsonian translocation chromosome
46,XX,der(14;21) (q10;q10), +21
what does the +21 indicate?
extra copy of chromosome 21
total of three copies of
chromosome 21, the patient manifests a
translocation type of down syndrome.
identify which here has 46,XX,der(14;21) (q10;q10), +21
edi yung may downsyndrome because of the presence of extra chromosome 21
chromosomes with 2 identical arms
isochromosomes
T or F. Both arms mirror each other due to the INVERSE division of the centromere or U-type exchange between sister chromatids along the centromere
F (transverse)
Abnormalities based on Cell Chromosomal Constituent (2 answers)
constitutional and acquired/somatic
→ found in all cells of the body
→ occurs very early in development (in meiosis I)
→ caused by defects in sperm or egg, anomalous fertilization, or abnormal episodes in the early embryo
constitutional
→ present only in certain tissues or cells
somatic/acquired
2 populations of cells (e.g. one 46 and one 47); there is a mosaic type of Down’s Syndrome
mosaicism
found in twins wherein there is infusion of cells from one to the other producing 2 populations of cells from the twin and their own
chimera
All of this are constistutional except?
A. defects in sperm or egg
B. anomalous fertilization
C. Down’s Syndrome
C
All of this are somatic except?
A. anomalous fertilization
B. chimera
C. mosaicism
D. acquired
A
