Chapter 6

Question 1

Metacentric

Answer 1

chromosome in which the two chromosome arms are approximately the same length

Question 2

Submetacentric

Answer 2

chromosome in which the centromere is displaced toward one end, producing a short arm and a long arm

Question 3

Acrocentric

Answer 3

chromosome in which the centromere is near one end, producing a long arm at one end and a knob, or satellite, at the other end

Question 4

Telocentric

Answer 4

chromosome in which the centromere is at or very near one end

Question 5

Chromosome Rearrangements

Answer 5

chromosome mutations that change the structures of individual chromosomes

Question 6

Chromosome Duplication

Answer 6

mutation that doubles a segment of a chromosome

Question 7

Tandem Duplication

Answer 7

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

Question 8

Displaced Duplication

Answer 8

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

Question 9

Reverse Duplication

Answer 9

when the duplication is inverted

Question 10

Segmental Duplications

Answer 10

duplicated chromosome segments larger than 1000 bp

Question 11

Chromosome Deletion

Answer 11

loss of a chromosome segment

Question 12

Pseudodominance

Answer 12

expression of a normally recessive allele due to a deletion on the homologous chromosome

Question 13

Haploinsufficient

Answer 13

appearance of a mutant phenotype in an individual cell or organism that is heterozygous for a normally recessive trait

Question 14

Chromosome Inversion

Answer 14

rearrangement in which a segment of a chromosome has been inverted 180 degrees

Question 15

Paracentric Inversion

Answer 15

chromosome inversion that does not include the centromere in the inverted region

Question 16

Pericentric Inversion

Answer 16

chromosome inversion that includes the centromere in the inverted region

Question 17

Position Effect

Answer 17

dependence of the expression of a gene on the gene’s location in the genome

Question 18

Dicentric Chromatid

Answer 18

chromosome that has two centromere; produced when crossing over takes place within a paracentric inversion

Question 19

Acentric Chromatid

Answer 19

chromatid that lacks a centromere; produced when crossing over takes place within a paracentric inversion

Question 20

Dicentric Bridge

Answer 20

structure produced when the two centromeres of a dicentric chromatid are pulled toward opposite poles, stretching the dicentric chromosome across the center of the nucleus

Question 21

Translocation

Answer 21

movement of genetic material between nonhomologous chromosomes or within the same chromosome

Question 22

Nonreciprocal Translocation

Answer 22

movement of a chromosome segment to a nonhomologous chromosome or chromosomal region with any reciprocal exchange of segments

Question 23

Reciprocal Translocation

Answer 23

reciprocal exchange of segments between two nonhomologous chromosomes

Question 24

Robertsonian Translocation

Answer 24

when the two long arms of two separate acrocentric chromosomes fuse to create one chromosome; the two short arms are usually lost

Question 25

Fragile Site

Answer 25

construction or gap that appears at a particular location on a chromosome when cells are cultured under special conditions

Question 26

Fragile-X Syndrome

Answer 26

a form of x-linked intellectual disability that appears primarily in males; associated with a fragile site that results from an expanding trinucleotide repeat

Question 27

Copy-Number Variation

Answer 27

difference among individual organisms in the number of copies of any large DNA sequence

Question 28

Structural Variant

Answer 28

collective term for chromosome rearrangements and copy-number variations

Question 29

Aneuploidy

Answer 29

change in the number of individual chromosomes; most often an increase or decrease in one or two chromosomes

Question 30

Polyploidy

Answer 30

possession of more than two sets of chromosomes

Question 31

Nondisjunction

Answer 31

failure of homologous chromosomes or sister chromatids to separate in meiosis or mitosis

Question 32

Nullisomy

Answer 32

absence of both member of a homologous pair of chromosome (2n-2)

Question 33

Monosomy

Answer 33

absence of one of the chromosomes from a homologous pair (2n-1)

Question 34

Trisomy

Answer 34

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

Question 35

Tetrasomy

Answer 35

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

Question 36

Down Syndrome

Answer 36

caused by the duplication of all or part of chromosome 21

Question 37

Primary Down Syndrome

Answer 37

human condition caused by the presence of three copies of chromosome 21

Question 38

Familial Down Syndrome

Answer 38

human condition caused by Robertsonian translocation in which the long arm of chromosome 21 is translocated to another chromosome; tends to run in families

Question 39

Translocation Carriers

Answer 39

individual organism heterozygous for chromosome translocation

Question 40

Edwards Syndrome

Answer 40

results from the presence of three copies of chromosome 18

Question 41

Patau Syndrome

Answer 41

results from the presence of three copies of chromosome 13

Question 42

Autopolyploidy

Answer 42

polyploid in which extra chromosome set are derived from the same species

Question 43

Allopolyploidy

Answer 43

polyploidy in which extra chromosome sets are derived from two or more species

Question 44

Unbalanced Gametes

Answer 44

gamete that has variant number of chromosomes; some chromosomes may be missing and other may be present in more than one copy