Module 3

Question 1

The complete set of chromosomes possessed by an organism; usually presented as a picture of a complete set of its metaphase chromosomes and arranged by length (longest to shortest).

Answer 1

karyotype

Question 2

Variations in the number and structure of chromosomes; often affects many genes and has large phenotypic effects.

Answer 2

Chromosome mutation

Question 3

Chromosome mutations that change the structures of individual chromosomes.

Answer 3

chromosome rearrangment

Question 4

Mutation that doubles a segment of a chromosome.

Answer 4

chromosome duplication

Question 5

Chromosome rearrangement in which a duplicated chromosome segment is adjacent to the original segment.

Answer 5

tandem duplication

Question 6

Chromosome rearrangement in which the duplicated segment is some distance from the original segment, either on the same chromosome or on a different one.

Answer 6

displaced duplication

Question 7

Duplication of a chromosome segment in which the sequence of the duplicated segment is inverted relative to the sequence of the original segment.

Answer 7

reverse duplication

Question 8

duplicated chromosome segments larger than 1000 bp

Answer 8

segmental duplication

Question 9

loss of a chromosome segment

Answer 9

chromosome deletion

Question 10

Rearrangement in which a segment of a chromosome has been inverted 180 degrees.

Answer 10

chromosome inversion

Question 11

Chromosome inversion that does not include the centromere in the inverted region.

Answer 11

paracentric inversion

Question 12

Chromosome inversion that includes the centromere in the inverted region.

Answer 12

pericentric inversion

Question 13

Chromatid that has two centromeres; produced when crossing over takes place within a paracentric inversion. The two centromeres of the dicentric chromatid are frequently pulled toward opposite poles in mitosis or meiosis, breaking the chromosome.

Answer 13

dicentric chromatid

Question 14

Chromatid that lacks a centromere; produced when crossing over takes place within a paracentric inversion. The acentric chromatid does not attach to a spindle microtubule and does not segregate in meiosis or mitosis, so it is usually lost after one or more rounds of cell division.

Answer 14

acentric chromatid

Question 15

Movement of genetic material between nonhomologous chromosomes or within the same chromosome.

Answer 15

translocation

Question 16

Movement of a chromosome segment to a nonhomologous chromosome or chromosomal region without any (or with unequal) reciprocal exchange of segments.

Answer 16

nonreciprocal translocation

Question 17

Reciprocal exchange of segments between two nonhomologous chromosomes.

Answer 17

reciprocal translocation

Question 18

Translocation in which the long arms of two acrocentric chromosomes become joined to a common centromere, generating a metacentric chromosome with two long arms and another chromosome with two very short arms.

Answer 18

robersonian translocation

Question 19

Change in the number of individual chromosomes; most often an increase or a decrease of one or two chromosomes.

Answer 19

aneuploidy

Question 20

Possession of more than two sets of chromosomes.

Answer 20

polyploidy

Question 21

Failure of homologous chromosomes or sister chromatids to separate in meiosis or mitosis.

Answer 21

nondisjunction

Question 22

Absence of both members of a homologous pair of chromosomes (2n - 2).

Answer 22

nullisomy

Question 23

absence of one of the chromosomes of a homologous pair

Answer 23

monosomy

Question 24

presence of an extra copy of a chromosome (2n + 1)

Answer 24

trisomy

Question 25

presence of two extra copies of a chromosome (2n + 2)

Answer 25

tetrasomy

Question 26

condition in which all the sets of chromosomes of a polyploid individual are derived from single species

Answer 26

autopolyploidy

Question 27

condition in which all chromosomes of a polyploid individual are from two or more species

Answer 27

allopolyploidy

Question 28

gamete that has a variable number of chromosome; some chromosomes may be missing and others may be present in more than one copy.

Answer 28

unbalanced gametes

Question 29

a mechanism to equalize the amount of protein produced by X-linked genes and autosomal genes. in placental mammals, dosage compensation is accomplished by the random inactivation of one X chromosome in the cells of females.

Answer 29

dosage compensation

Question 30

Chromosome duplications often result in abnormal phenotypes because: a. developmental processes depend on the relative amounts of proteins encoded by different genes. b. extra copies of the genes within the duplicated region do not pair in meiosis. c. the chromosome is more likely to break when it loops in meiosis. d. extra DNA must be replicated, which slows down cell division

Answer 30

a. developmental processes depend on the relative amounts of proteins encoded by different genes

Question 31

a dicentric chromosome is produced when crossing over takes place in an individual heterozygous for which type of chromosome rearrangement? a. duplication b. deletion c. paracentric inversion d. pericentric inversion

Answer 31

c. paracentric inversion

Question 32

what is the outcome of a Robertsonian translocation? a. two acrocentric chromosomes b/ one metacentric chromosome and one chromosome with two very short arms c. one metacentric and one acrocentric chromosome d. two metacentric chromosomes

Answer 32

b. one metacentric chromosome and one chromosome with two very short arms

Question 33

Why are sex-chromosome aneuploidies more common than autosomal aneuploidies in humans and other mammals?

Answer 33

Dosage compensation prevents the expression of additional copies of X-linked genes in mammals, and there is little information in the Y chromosome, so extra copies of the X and Y chromosomes do not have major effects on development. In contrast, there is no mechanism of dosage compensation for autosomes and so extra copies of autosomal genes are expressed, upsetting development and causing the spontaneous abortion of aneuploid embryos.

Question 34

Species A has 2n = 16 chromosomes and species B has 2n = 14. How many chromosomes would be found in an allotriploid of these two species? a. 21 or 24 b. 42 or 48 c. 22 or 23 d. 45

Answer 34

c. 22 or 23

Question 35

what are the four types of rearrangements?

Answer 35

duplications, deletions, inversions, translocations

Question 36

when the duplicated segment incorporates next to the original corresponding segment.

Answer 36

tandem duplication

Question 37

when the duplicated segment incorporates next to the original corresponding segment but in the reverse order.

Answer 37

reverse duplication

Question 38

when the duplicated segment incorporates in a location on the same chromosome that is not adjacent to the original segment.

Answer 38

displaced duplication

Question 39

mutation in which a part of a chromosome is lost or missing.

Answer 39

chromosome deletion

Question 40

a segment of a chromosome is turned 180 degrees.

Answer 40

chromosome inversion

Question 41

inversion that does not include the centromere

Answer 41

paracentric inversion

Question 42

inversion that does include the centromere

Answer 42

pericentric inversion

Question 43

when parts of chromosomes move to other nonhomologous chromosomes or to other regions of the same chromosome.

Answer 43

translocation

Question 44

classes of translocations

Answer 44

nonreciprocal, reciprocal and Robertsonian

Question 45

genetic material moves from one chromosome to another without any reciprocal exchange.

Answer 45

nonreciprocal translocation

Question 46

there is a two-way exchange of segments between the chromosomes.

Answer 46

reciprocal translocation

Question 47

However, it is common for deletions to result when a translocation occurs, particularly when two acrocentric chromosomes are involved.

Answer 47

Robertsonian translocation

Question 48

change in the number of individual chromosomes.

Answer 48

aneuploidy

Question 49

increase in the number of chromosome sets.

Answer 49

polyploidy

Question 50

loss of both members of a homologous pair

Answer 50

nullisomy

Question 51

loss of a single chromosome

Answer 51

monosomy

Question 52

gain of a single chromosome

Answer 52

trisomy

Question 53

game of two homologous chromosomes

Answer 53

tetrasomy

Question 54

When can aneuploidy occur

Answer 54

1. A chromosome may be lost during either mitosis or meiosis. If the centromere was deleted, the spindle microtubules would no longer be able to attach and move the chromosomes to their correct end destination. 2. The small chromosome produced after a Robertsonian translocation has taken place is lost during mitosis or meiosis. 3. Nondisjunction occurs, in which the homologous chromosomes or sister chromatids fail to separate in mitosis or meiosis.

Question 55

all chromosomes sets are from a single species

Answer 55

autopolyploidy

Question 56

hybridization between two species

Answer 56

allopolyploidy

Question 57

Chromosome duplications often result in abnormal phenotypes because

Answer 57

developmental processes depend on the relative amounts of proteins encoded by different genes.​

Question 58

A dicentric chromosome is produced when crossing over takes place in an individual heterozygous for which type of chromosome rearrangement?

Answer 58

paracentric inversion

Question 59

What is the outcome of a Robertsonian translocation?

Answer 59

one metacentric chromosome and one chromosome with two very short arms

Question 60

Species A has 2n = 16 chromosomes and species B has 2n = 14. How many chromosomes would be found in an allotriploid of these two species?

Answer 60

22 or 23

Question 61

Which is NOT a type of chromosomal mutation?

Answer 61

point mutation

Question 62

Can chromosome duplications cause negative effects to an organism? Why?

Answer 62

Yes. Duplicated regions increase gene dosage, which affects processes like development that require specific amounts of protein.

Question 63

Which is NOT an effect of chromosomal translocations?

Answer 63

Translocations can cause regions of the chromosome to be duplicated.

Question 64

Trisomy and monosomy can be a product of nondisjunction in:

Answer 64

meiosis I and II, and mitosis

Question 65

Aneuploids of which chromosomes are less likely to result in a live birth?

Answer 65

larger autosomes

Question 66

A diploid species has a total of 52 chromosomes. How many chromosomes would be found in a monosomy, trisomy, and autotriploid?

Answer 66

51, 53, 78

Question 67

One species has 32 chromosomes and another species has 24 chromosomes. In an allotriploid of these two species, how many chromosomes would there be?

Answer 67

44 or 40