Ch 12-2 Flashcards
Linked genes are inherited together at ______ rates than unlinked genes.
Higher
The recombination frequency for unlinked genes is ______%.
50
______ is the process that alters allelic combinations during prophase I of meiosis.
Crossing over
___ results from the fertilization of an abnormal diploid egg.
Triploidy
______ is the transfer of a chromosome segment to another chromosome.
Translocation
______ and ______ are common means of fetal testing.
Amniocentesis, chorionic villus sampling
Down syndrome is caused by ______ of chromosome 21.
Trisomy
The frequency of aneuploidy increases with ______ age.
Maternal
Klinefelter syndrome is characterized by the ______ karyotype.
Xxy
Wolf-Hirschhorn Syndrome is caused by a deletion in chromosome ______.
4
What is the recombination frequency for completely linked genes?
a) 0%
b) 25%
c) 50%
d) 100%
A
Which of the following is NOT a type of structural chromosomal alteration?
a) Deletion
b) Duplication
c) Inversion
d) Nondisjunction
D
What is the karyotype for Turner syndrome?
a) XXY
b) XO
c) XXX
d) XYY
B
Which syndrome is associated with a deletion on chromosome 5?
a) Down syndrome
b) Turner syndrome
c) Cri du chat syndrome
d) Wolf-Hirschhorn syndrome
C
What is the maximum recombination frequency for linked genes?
a) 25%
b) 50%
c) 75%
d) 100%
B
Which of the following is a viable monosomy in humans?
a) Monosomy 21
b) Monosomy X
c) Monosomy 18
d) Monosomy Y
B
What type of chromosomal alteration results in the Philadelphia chromosome?
a) Deletion
b) Duplication
c) Inversion
d) Translocation
D
Which condition is associated with three X chromosomes?
a) Turner syndrome
b) Klinefelter syndrome
c) XXX syndrome
d) XYY syndrome
C
What is the frequency of Klinefelter syndrome in individual births?
a) 1/100
b) 1/500 to 1/1000
c) 1/2500
d) 1/10000
B
Which process is responsible for the formation of gametes with abnormal chromosome numbers?
a) Mitosis
b) Nondisjunction
c) Crossing over
d) Independent assortment
B
True or False: Completely linked genes always result in recombinant offspring.
False. Completely linked genes result in all offspring being parental type.
True or False: Aneuploidy is the most common reason for early stage pregnancy loss.
T
True or False: Polyploidy is well-tolerated in humans.
False. Polyploidy is not tolerated in humans but is tolerated by some other organisms.
True or False: Inversions always result in a change in gene copy number.
False. Inversions do not change gene copy number but may alter gene regulation.
True or False: The frequency of aneuploidy decreases with maternal age.
False. The frequency of aneuploidy increases with maternal age.
True or False: XYY individuals typically show no phenotypic effects.
T
True or False: Turner syndrome is the only known viable monosomy in humans.
T
True or False: Cri du chat syndrome is caused by a duplication on chromosome 5.
False. Cri du chat syndrome is caused by a deletion on chromosome 5.
True or False: Nondisjunction can occur during both meiosis and mitosis.
.
T
True or False: The Philadelphia chromosome is associated with Down syndrome.
False. The Philadelphia chromosome is associated with chronic myelogenous leukemia (CML).
What is complete linkage?
Genes on the same chromosome, very close together, resulting in 0% recombination and all offspring being parental type.
Define aneuploidy.
An abnormal chromosome number due to nondisjunction, resulting in either monosomy (one copy) or trisomy (three copies) of a chromosome.
What is the Philadelphia chromosome?
A chromosomal alteration resulting from a translocation, implicated in chronic myelogenous leukemia (CML).
What is a centiMorgan?
A unit of genetic distance equal to 1% recombination frequency or 1 map unit.
What is polyploidy?
The presence of more than two complete sets of chromosomes in all somatic cells.
What is Turner syndrome?
A condition resulting from monosomy X (XO), occurring in 1/2500 births and generally causing sterility.
What causes Cri du chat syndrome?
A deletion on chromosome 5, resulting in a characteristic cat-like cry and intellectual disability.
What is mosaicism?
A condition where an individual has two or more genetically distinct cell populations, often due to mitotic nondisjunction.
What is a karyotype?
A visual representation of an individual’s chromosomes, arranged by size and banding pattern.
What is the Barr body?
The inactivated and condensed X-chromosome in XX individuals.
