Ethics Chapter 13
The most common autosomal aneuploids among newborns are represented by ______.
- Edwards syndrome - Patau syndrome - Down syndrome
What are some disadvantages of chorionic villus sampling?
- Inborn errors in biochemical processes cannot be detected. - A mutation can occur in villus cells or in the fetus, leading to a false positive or false negative outcome.
Which of the following syndromes is inherited via the phenomenon of uniparental disomy?
- Prader-Willi syndrome - Angelman syndrome
Which of the following types of chromosomes are present in humans?
- Submetacentric - Acrocentric - Metacentric
A couple seeks testing and counseling after they have a child with cystic fibrosis. Testing reveals that the mother is a carrier, but the father is not. How can these results be explained?
- The man tested is not the biological father - Uniparental disomy from the mother - A mutation altered the child's normal allele
Which individuals will have Turner (45,X) syndrome?
- Those missing one X chromosome in its entirety - Those who are mosaics, with only some cells missing an X chromosome - Those missing only part of one X chromosome
In the absence of karyotype analysis, which two conditions could be indicated if DNA sequencing shows that a fetus has an overrepresentation of SNPs from chromosome 21?
- Trisomy 21 Down syndrome - Translocation Down syndrome
Which types of chromosome combinations can be included in gametes by a carrier of a reciprocal translocation?
- Two normal copies of the two involved chromosomes can be transmittted - Either translocated chromosome can be transmitted, which introduces extra or missing genetic material and would affect the phenotype - Two abnormal copies can be transmitted, with no effect on the phenotype of an offspring unless a vital gene is disrupted
When does an insertional translocation cause symptoms?
- When the inserted DNA disrupts a vital gene - When crucial DNA sequences are present in excess - When crucial DNA sequences are lost
Which of the following are possible explanations for the age factor in trisomy 21 Down syndrome? An oocyte released during ovulation in an older mother may be a(n) ______.
- immature aneuploid occyte that has been stored in the ovary - normal oocyte that has been exposed to mutagens affecting chromosomal segregation prior to and after ovulation
Two types of inversions are distinguished by the position of the centromere relative to the inverted section. These are called
- pericentric - paracentric
For a couple where one parent has a Robertsonian translocation between chromosome 21 and chromosome 14, the theoretical risk of giving birth to a child with translocation Down syndrome is ______.
1/3
Noninvasive prenatal diagnosis is performed starting at ______ of pregnancy.
10 weeks
For the chromosomal location listed as 11p15.5, match the number or letter on the left with its meaning on the right.
11: Chromosome number p: Chromosome arm 15.5: Chromosome subband identified by staining and FISH
Approximately ____ percent of spontaneous abortions result from triploidy.
17
Individuals with Edwards syndrome have three copies of chromosome ____.
18
Individuals with 45, X syndrome demonstrate that ____ X chromosome(s) are necessary for normal sexual development.
2
A carrier of a Robertsonian translocation has ______ chromosomes, but may not have symptoms if no crucial genes have been deleted or damaged.
45
Only 50% of individuals with Turner syndrome are ______, the rest either ______ or are mosaics..
45,X; are missing part of an X chromosome
Which chromosome composition would lead to a male with abnormal sexual development?
47,XXY
Which of the following syndromes has been controversially linked to criminal behavior?
47,XYY syndrome
Approximately ____ percent of spontaneous abortions result from atypical chromosomes.
50
Cri-du-chat syndrome is associated with which of the following?
A deletion of the short arm of chromosome number 5
What would an individual with the chromosomal description 45, X be?
A female with abnormal sexual development
What would an individual with the sex chromosome composition 47,XXY be?
A male with abnormal sexual development
This figure shows the four types of chromosomes based on centromere position. Match each letter to its correct chromosome type.
A. Telocentric B. Acrocentric C. Submetacentric D. Metacentric
The following figure represents a replicated chromosome. Match the letter to its appropriate structure.
A. telomeres B. heterochromatin C. centromere D. euchromatin
Match the result of a chorionic villus sampling test on the right with the explanation on the left.
Accurate: Fetal and chorionic villus cells have the same chromosomal composition. False Positive: A mutation occurred in a chorionic villus cell that is not present in fetal cells. False Negative: A mutation occurred in a fetal cell that is not present in chorionic villus cells.
In which type of chromosome is the centromere located very near one end so that the shorter arm is very small?
Acrocentric
Individuals with Down syndrome who live past age 40 are also at risk for developing changes in the brain that are characteristic of which condition?
Alzheimer disease
Which of the following are prenatal diagnostic procedures that are performed to detect fetal abnormalities?
Amniocentesis; Chorionic villus sampling
Identify the set of symptoms exhibited by a female with 45,X syndrome.
At sexual maturity, she develops sparse body hair, but she does not ovulate or menstruate, and her breasts do not develop.
Which of the following very small sequences are detected by a technique called comparative genomic hybridization?
CNVs
Which of the following is an accurate comparison of amniocentesis and chorionic villus sampling (CVS)?
CVS can be performed at an earlier stage of pregnancy.
Which of the following human chromosomes is the largest in size?
Chromosome 1
_____ is a syndrome in which part of the short arm of one copy of chromosome 5 is missing.
Cri-du-chat syndrome
_____ is the area of genetics that links chromosome variations to specific traits, including illnesses.
Cytogenetics
Which syndrome is characterized by a person who is usually short and has straight and sparse hair, and a tongue protruding through thick lips? The hands have an atypical pattern of creases, the joints are loose, and poor reflexes and muscle tone give a floppy appearance.
Down syndrome
Which condition is caused by trisomy 18?
Edwards syndrome
Which of the following utilizes labeled DNA probes?
Fluorescence in situ hybridization
Match the following types of chromosomes based on centromere position (in the left column) with their appropriate descriptions (in the right column
Metacentric chromosome: The centromere divides the chromosome into two arms of approximately equal length. Submetacentric chromosome: The centromere establishes one long arm and one short arm in the chromosome. Acrocentric chromosome: The centromere is present near an end of the chromosome. Telocentric chromosome: The centromere is present toward one end although telomere DNA sequences are still at the tip.
How does chromothripsis in a mother lead to severe birth defects in her offspring?
Mispairing of chromosomes during meiosis leads to deletions and duplications
In humans, chromosomes are duplicated and transmitted via what type(s) of cell division?
Mitosis and meiosis
What is illustrated in this figure?
Nondisjunction during meiosis I
Which of the following are the two types of inversions?
Pericentric and paracentric
Which of the following accurately reflects the composition of a chromosome?
Primarily made of DNA and proteins with a small amount of RNA
Which best describes the DNA sequences that are found in the centromere
Repeats of a specific 171-base sequence
______ arise when telomeres are lost, leaving sticky ends that adhere.
Ring chromosomes
What is the name describing a situation in which the short arms of two different acrocentric chromosomes break, leaving sticky ends on the two long arms that join, forming a single, large chromosome with two long arms?
Robertsonian translocation
If one parent has a ____ between chromosome 21 and chromosome 14, theoretically there is a one in three risk that the mother will give birth to a child with translocation Down syndrome.
Robertsonian; translocation
In the cell cycle, centromeres replicate toward the end of _____ phase.
S
Which set of symptoms is exhibited by a girl with triplo-X?
She has a tall stature and menstrual irregularities; she also tends to be less intelligent than her siblings with the normal number of X chromosomes.
_____ include some protein-encoding genes and therefore bridge the gene-rich regions and the telomere repeats.
Subtelomeres
_____ chromosomes are not found in humans.
Telocentric
Which statement about human chromosome types is true?
There are 24 of them: Numbers 1-22, X and Y
Suppose a child is born who is homozygous for a Robertsonian translocation joining chromosomes 14 and 15. What is most likely true about the parents?
They are related to each other and inherited the translocation from a shared ancestor.
______ can be inherited because they can be present in carriers, who have the normal amount of genetic material, but it is rearranged.
Translocations
Which condition can lead to severe changes to the eye, including the absence of an eye, development of a small eye, or fusion of two eyes into one large eyelike structure?
Trisomy 13
_____ can result from inheriting or originating a reciprocal translocation, just as they can from a Robertsonian translocation.
Unbalanced gametes
Which set of symptoms is exhibited by an individual with 47,XXY syndrome?
Underdeveloped sexually, with rudimentary testes and prostate glands and sparse pubic and facial hair
Two-thirds of all triploids result from the fertilization of _____.
a haploid oocyte by two haploid sperm
Suppose the results of a blood test show that a pregnant woman's levels of specific biochemicals are outside the range that would be expected if she were carrying a fetus with the normal number of chromosomes. This suggests that the fetus has an elevated risk of having a(n) ______.
abnormal chromosome number
This figure shows a single crossover between a chromosome with a paracentric inversion and its normal homolog. The molecule that is circled (on the right hand side) is called a(n) ___ ___.
acentric; fragment
The likelihood of giving birth to a child with trisomy 21 Down syndrome increases dramatically with the ___ of the mother
age
A similarity between amniocentesis and chorionic villus sampling is that both _____.
allow direct visualization of chromosomes
This figure illustrates a prenatal genetic procedure called
amniocentesis
The two traditional technologies that provide images of chromosomes from a fetus are ____ and ____ ____ sampling(CVS)
amniocentesis; chorionic; villus
Suppose DNA sequencing of tissue from a miscarriage showed that the fetus had an overrepresentation of SNPs from chromosome 21. Which additional type of analysis would be needed to determine if the fetus had the extra material due to trisomy 21 Down syndrome or translocation Down syndrome?
analysis of a karyotype
In nondisjunction, a chromosome pair fails to separate at _____ of either the first or second meiotic division.
anaphase
Cells missing a single chromosome or having an extra chromosome are said to be ___, which means "not good set."
aneuploid
The set of symptoms exhibited by a male with 48,XXYY syndrome is ______.
attention deficit disorder, obsessive compulsive disorder, autism, and learning disabilities typically developing by adolescence
An ideogram shows chromosome arms and numbered regions called ____ and ____
bands; subbands
In the process of genome editing, the shut-off chromosome 21 formed a(n) ____ ____, which normally happens when XIST silences one X chromosome in a female cell.
barr; body
Chorionic villus sampling is usually performed ______ of pregnancy.
between 10 and 12 weeks
Amniocentesis is usually performed ______ of gestation.
between 14 and 16 weeks
An indirect type of test measures ______ whose levels in the blood are within a certain range in a pregnant woman carrying a fetus with the normal number of chromosomes, but may lie outside that range in fetuses whose cells have an extra copy of a certain chromosome.
biochemicals
A comparison of ______ and the parental haplotypes for a specific chromosomal region is used to determine whether a fetus has inherited a single-gene condition.
cell-free fetal DNA analysis
A paracentric inversion does not include a _____.
centromere
Many of the hundreds of thousands of DNA bases that form the chromosomal ___ are copies of a specific 171-base DNA sequence.
centromere
The largest constriction of a chromosome is called the
centromere
Molecules of _____ stay with centromeres as chromosomes replicate, covering about half a million DNA base pairs.
centromere protein A (CENP-A)
This figure illustrates a prenatal genetic procedure called _____ ____ ____.
chorionic villus sampling
Using amniocentesis, a karyotype can show large ____ abnormalities, and biochemical and single-gene tests can reveal inborn errors of ___
chromosomal; metabolism
The term aneuploidy refers to a change in ______.
chromosome number that is not a complete set
A situation occurring in cancer cells and other rare instances when multiple double-stranded chromosome breaks appear to "shatter" a chromosome and may resolve with those DNA fragments being integrated into other chromosomes through repair mechanisms is called ______.
chromothripsis
In the context of microdeletions and microduplications, _____ compares the abundance of copies of a particular CNV in the same amount of DNA from two sources—one with a medical condition, one healthy.
comparative genomic hybridization
The field of genetics that correlates the structure, number, and behavior of chromosomes with heredity and variation is called
cytogenetics
A chromosomal mutation in which a segment of the chromosome is missing is called a(n)
deletion
A(n) _____ is a type of copy number variant with missing DNA sequences.
deletion
An abnormal chromosome that has two centromeres is termed a(n) ____ chromosome
dicentric
Individuals with ___ syndrome have an increased risk of developing black tau fibers and amyloid beta protein deposits characteristic of Alzheimer disease.
down
A chromosomal mutation in which a chromosome has an extra segment is known as a(n)
duplication
An ___ is a type of copy number variant with additional DNA sequences
duplication
A crossover in a pericentric inversion produces two chromosomes that have _____.
duplications and deletions with one centromere each
In most cell types, telomeres shorten with _____.
each mitotic cell division
While using stains and dyes, the _____ present in chromosomes stains lightly.
euchromatin
A normal chromosome number is said to be ___, which means "good set"
euploid
True or false: Men with XXYY syndrome, also known as 48,XXYY syndrome, have fathered children with medical assistance.
false
True or false: Turner or XO or 45,X syndrome is found more frequently among newborns than spontaneously aborted fetuses.
false
With regard to uniparental disomy, a child with Angelman syndrome can have two parts of the long arm of chromosome 15 from his/her ______.
father
A technique called _____ has the ability to highlight individual genes on a chromosome.
fluorescence in situ hybridization
A newer approach, called _____, is being used to study Down syndrome at the cellular level. This technique "borrows" the mechanism that shuts off one X chromosome in the cells of females.
genome editing
Chorionic villus sampling is a procedure for genetic testing that ______.
harvests placental cells for prenatal genetic analysis
Centromeres lie within vast stretches of ______.
heterochromatin
Which of the following would have a dark appearance when using stains and dyes to visualize chromosomes?
heterochromatin
Heterochromatin consists mostly of ______ sequences.
highly repetitive DNA
This schematic chromosome map is called a(n)
ideogram
On a human chromosome, the number of protein-encoding sequences tends to ______ as the distance from the centromere increases.
increase
A polyploid refers to a(n) ______.
individual that has more than two sets of chromosomes
A rare type of translocation is a(n) _____, in which part of one chromosome integrates into a nonhomologous chromosome.
insertional translocation
Inversions with devastating effects can be traced to meiosis, when a crossover occurs between the _____.
inverted chromosome segment and the noninverted homolog
A characteristic of a centromere is that it ______.
is where spindle fibers attach when the cell divides
An ___ is a chromosome that has identical arms.
isochromosome
When centromeres divide along the wrong plane, structures with identical arms called ___ are formed
isochromosomes
The display of chromosomes shown here is called a(n)
karyotype
The standard chromosome chart, or _____, remains a major clinical tool in genomics.
karyotype
Certain centromere-associated proteins are synthesized only when mitosis is imminent, forming a structure called a _____ that contacts the spindle fibers, enabling the cell to divide.
kinetochore
The structure associated with the centromere that contacts the spindle fibers during mitosis is the
kinetochore
During inversion, to allow the genes to align, the inverted chromosome forms a(n) _____.
loop
A mutation is considered a chromosomal aberration if it is large enough to be seen using staining and microscopic techniques to show DNA sequences that have been ______.
lost; moved; added
47,XXY syndrome is the most common genetic or chromosomal cause of _____.
male infertility
The increased risk of Down syndrome correlates to _____.
maternal age
Centromere position is one physical feature of chromosomes. A chromosome is said to be ___ if the centromere divides it into two arms of approximately equal length.
metacentric
A karyotype typically displays chromosomes obtained from mitotic ______, when DNA coils tightly, enabling them to be visualized.
metaphase
Multiple deletions and duplications can occur in offspring of a mother with chromothripsis due to ______ during ______.
mispairing of chromosomes; meiosis
A child born with one missing chromosome has a condition called
monosomy
______ embryos and fetuses with atypical chromosomes stop developing before birth.
most
With regard to uniparental disomy, a child with Prader-Willi syndrome can have two parts of the long arm of chromosome 15 from his/her ______.
mother
Failure of chromosomes to separate normally during meiosis or mitosis is termed
nondisjunction
In the context of aneuploidy, _____ produces a sperm or oocyte that has two copies of a particular chromosome, or none, rather than the normal one copy.
nondisjunction
The meiotic error that causes aneuploidy is called _____.
nondisjunction
This figure highlights the process of
nondisjunction; second
Testing cell-free fetal DNA in the woman's bloodstream is an example of a technology called ______.
noninvasive prenatal diagnosis
The term euploidy refers to a(n) ______.
normal number of sets of chromosomes.
Chromosome stalks and their satellites coalesce to form the _____, a structure in the nucleus where ribosomal building blocks are produced and assembled.
nucleolus
The location of the gene that is mutated in Severe Combined Immune Deficiency is listed as 20q13.12. This means that the gene is located ______.
on the long arm of chromosome 20
A person who is homozygous for a Robertsonian translocation most likely inherited ___ copy(ies) of the chromosome with the translocation from ___ parent.
one; each
In a chromosome, the short arm is called ______, while the long arm is called ______.
p; q
The short arm of a chromosome is represented with the letter ___, , while the long arm is designated ____.
p; q
An inversion in which the inverted chromosome segment does not include the centromere is called a(n) ____ inversion
paracentric
An inversion in which the inverted chromosome segment includes the centromere is called a(n) ____ inversion
pericentric
For a ______, a centromere is included within the loop formed by pairing of homologs during meiosis.
pericentric inversion
This figure shows the outcome of a single crossover between a chromosome with a(n) ______ and its normal homolog.
pericentric inversion
A cell with extra sets of chromosomes is said to be
polyploid
Chromothripsis is a ______.
process that causes multiple double-stranded breaks and shatters a chromosome
Euchromatin has more _____ sequences than heterochromatin.
protein-encoding
Mutations ______.
range from single-base changes to entire extra sets of chromosomes
In a(n) _____, two different chromosomes exchange parts, but the translocation carrier has a normal amount of genetic material that is rearranged.
reciprocal translocation
This figure shows a type of chromosomal mutation called a(n)
reciprocal; translocation
A characteristic of Robertsonian translocation is that the tiny short arms of the acrocentric chromosomes are lost, but their DNA sequences are _____.
repeated elsewhere in the genome, so the loss does not cause symptoms
This figure illustrates the formation of a(n) ____ chromosome
ring
Five human chromosomes (13, 14, 15, 21, and 22) have bloblike ends, called _____, that extend from the rest of a chromosome by a thinner, stalklike bridge.
satellites
Cell-free fetal DNA analysis can be used to detect ______ by comparing fetal DNA to haplotypes from blood samples of the parents for the same chromosomal regions.
single-gene conditions
A karyotype displays chromosomes in pairs by
size
Reciprocal translocations usually occur in ______.
specific chromosomes that have unstable parts
The chromosome parts that lie between protein-rich areas and the telomeres are termed
subtelomeres
Reciprocal translocations usually occur in specific chromosomes that have vulnerable parts of chromosomes, where the DNA is _____.
symmetrical in sequence so that complementary base pairing occurs within the same DNA strand, folding it into loops
The end of a linear chromosome is called a(n)
telomere
In this schematic of a chromosome, the letter A (top bracket) depicts which of the following?
the P arm
The sex chromosome aneuploid 47,XYY occurs as a result of nondisjunction during gamete formation in ______.
the father
It is generally assume that chorionic villi cells and fetal cells will have the same chromosomal content because ______.
they both originate from the fertilized ovum
Individuals with Down syndrome usually have ______ copies of chromosome 21.
three
An ____ is a type of mutation where different (nonhomologous) chromosomes exchange or combine parts.
translocation
An ___ ___, who has 45 chromosomes, may not have symptoms. However, they would produce unbalanced gametes—sperm or oocytes with too many or too few genes that can lead to spontaneous abortion or birth defects
translocation; carrier
About 1 in every 1,000 females has an extra X chromosome in each of her cells, a condition called _____.
triplo-X
A(n) ___ cell is designated 3N.
triploid
An individual whose cells have three copies of each chromosome is a(n) _____.
triploid
Considering the autosomes (chromosomes 1-22), this figure shows a condition in humans called ______
triploidy
An individual who has three copies of a single chromosome is said to be _____.
trisomic
If a cell-free fetal DNA analysis shows that the mother's blood has 50% more DNA pieces from chromosome 21 than from the other chromosomes, this indicates that her fetus is ______ for chromosome 21.
trisomic
Uniparental disomy can arise from a(n) ______ embryo in which some cells lose the extra chromosome, leaving two homologs from one parent.
trisomic
Fusion of the developing eyes so that a fetus has one large eyelike structure in the center of the face is seen in _____.
trisomy 13
Milder signs of ______ include overlapping placement of fingers, a narrow and flat skull, low-set ears, a small mouth, unusual fingerprints, and rocker-bottom feet.
trisomy 18
This figure shows the hands of an infant with ______.
trisomy 18
The most common autosomal aneuploid among liveborns is _____, because this chromosome has the fewest genes.
trisomy 21
In an analysis of cell-free fetal DNA, blood from a woman whose fetus has ______ 21 has 50 percent ______ DNA pieces of chromosome 21 than it does from the other chromosomes.
trisomy; more
True or false: Certain human cells may be polyploid.
true
True or false: Most autosomal aneuploids cease developing long before birth.
true
Inheriting two chromosomes or chromosome segments from one parent is a condition called ____ ____
uniparental; disomy
Amniocentesis is a procedure for genetic testing that ______.
uses fluid from the uterus to grow fetal cells
