Chapter 9

Question 1

Chromosome Mutation

Answer 1

variation in the number and structure of chromosomes

Question 2

Metacentric Chromosome

Answer 2

Centromere is in the center f the chromosome, chromosome has arms of equal length

Question 3

Submetacentric Chromosome

Answer 3

centromere is displaced towards one end, creating a long arm (q) and a short arm (p)

Question 4

Acrocentric Chromosome

Answer 4

centromere is near one end

Question 5

Telocentric Chromosome

Answer 5

cntromere is at one end of the chromosome

Question 6

Chromosome Rearrangement

Answer 6

alter the structure of chromosomes

Question 7

Chromosome Duplication

Answer 7

a mutation in which part f the chromosome have been doubled

either in tandem (adjacent to the original segment), displaced (not next to the original segment) or reversed (the duplication is inverted)

Question 8

Chromosome Deletion

Answer 8

the loss of a chromosome segment; in individuals heterozygous for deletions, the normal chromosome must loop during the pairing of homologs in prophase I to allow the homolog regions to align and undergo synapsis

if the deletion includes the centromere, the chromosome ill not be able to separate in mitosis or meiosis and will be lost

Question 9

Pseudodominance

Answer 9

a result of chromosome deletion; an expression of a normally recessive mutation

Question 10

Haploinsufficient Gene

Answer 10

a result of chromosome deletion; when a single copy of a gene is insufficient to produce a wild-type phenotype; some genes must be present in 2 copies for normal function

Question 11

Chromosome Inversion

Answer 11

when a chromosome segment is inverted (turned 180 degrees); the chromosome is broken in 2 places

Question 12

Pericentric Inversion

Answer 12

inversions that include the centromere

Question 13

Paracentric Inversion

Answer 13

inversions that do not include the centromere

Question 14

Position Effect

Answer 14

when the position of genes are altered by an inversion and they are expressed at inappropriate times/in inappropriate tissues

Question 15

Translocation

Answer 15

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

Question 16

Nonreciprocal Translocation

Answer 16

genetic material moves from one chromosome to another without any reciprocal change

Question 17

Reciprocal Translocation

Answer 17

more common, a two-way exchange of segments between 2 nonhomologous chromosomes

Question 18

Robertsonian Translocation

Answer 18

when the long arms of 2 acrocentric chromosomes become joined to a common centromere through a translocation, generating a metacentric chromosome with2 long arms and another chromosome with 2 short arms

Question 19

Aneuploidy

Answer 19

a change in the number of individual chromosomes

Question 20

Polyploidy

Answer 20

a change in the number of chromosome sets

Question 21

Nullisomy

Answer 21

the loss of both members fa homologous pair of chromosmes; 2n-2

in humans, 2n=46, so nullisomy = 44

Question 22

Monosomy

Answer 22

the loss of a single chromosome; 2n-1

in humans, 2n=46 so monosomy = 45

Question 23

Trisomy

Answer 23

the gain of a single chromosome, meaning 3 homologous copies of one chromosome; 2n+1

in humans, 2n=46 so trisomy = 47

Question 24

Tetrasomy

Answer 24

the gain of 2 homologous chromosomes, meaning 4 homologous copies of one chromosome, 2n+2

in humans, 2n=46, so tetrasomy = 48

Question 25

Down Syndrome

Answer 25

the most common aneuploidy in humans, 1/700 births are D.S. births, maternal in origin, usually arises in meiosis I, little hereditary tendency

Question 26

Trisomy 21

Answer 26

a.k.a. down syndrome

Question 27

Translocation Carrier

Answer 27

people with the translocation gene (usually between chromosomes 14 and 21); these carriers do not have down syndrome, only possess 45 chromosomes but their phenotypes are normal. increased chance of offspring with D.S.

Question 28

Turner Syndrome

Answer 28

when cells contain an X chromosome and no Y chromosome (XO); people with this condition are female, don’t undergo puberty, broad chest, folds of skin on neck, and are normally sterile and have normal intelligence; 1/3000 births

Question 29

Klinefelter Syndrome

Answer 29

contain one or more Y chromosome and multiple X chromosomes (XXY, XXXY, etc.), male, small tested, breast enlargement, reduced facial and pubic hair, often tall, sterile, normal intelligence. 1/1000 births

Question 30

Uniparental Disomy

Answer 30

when both chromosomes are from the same parent; probably originate as a trisomy

Question 31

Mosaicism

Answer 31

a nondisjunction that leads to regions of tissue with different chromosome constitutions; very common