Chapter 8

Question 1

Metacentric

Answer 1

the centromere is located in the middle so the chromosome has two arms of equal length

Question 2

Submetacentric

Answer 2

the centromere is displaced toward one end, creating a long arm and a short arm

Question 3

aneuploidy

Answer 3

number of chromosomes is altered; one or more individual chromosomes are added or deleted

Question 4

polyploidy

Answer 4

one or more complete sets of chromosomes are added

Question 5

chromosome rearrangements

Answer 5

chromosome mutations that change the structure of individual chromosomes

Question 6

four types of rearrangements

Answer 6

• duplications
• deletions
  -inversions
• translocations

Question 7

chromosome duplication

Question 8

tandem duplication

Answer 8

duplication segment is immediately adjacent to the original segment

Question 9

Displaced duplication

Answer 9

duplicated segment is located some distance from the original segment, either on the same chromosome or on a different one

Question 10

reverse duplication

Answer 10

when duplication is inverted

Question 11

where do duplications and deletions originate from

Answer 11

unequal crossing over, in which chromosomes misalign duirng crossing over

Question 12

what happens when an individual is heterozygous for a chromosome inversions?

Answer 12

in prophase I of meiosis, the chromosome form an inversion loop, which allows the homologous sequences to align

Question 13

Paracentric Inversions

Answer 13

• creates a dicentric chromatid and acentric chromatid
• inversions that do not include a centromere
• forms dicentric bridge
• bridge breaks
• four gametes produced, two contain the original nonrecombinant chromosomes , other two contain recombinant chromosomes

Question 14

Pericentric inversion

Answer 14

• recombinant chromosomes have too many copies of some genes and no copies of others, so gametes that receive the recombinant chromosomes can’t produce a progeny

Question 15

translocation

Answer 15

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 exchange

Question 17

reciprocal translocation

Answer 17

two way exchange of segments between chromosomes

Question 18

Robertsonian translocation

Answer 18

the short arm of one acrocentric chromosome is exchanged with the long arm of another

Question 19

consequences of translocation

Answer 19

-change in local gene environment
- differences in chromatin structure
- may alter gene expression

Question 20

aneuploidy

Answer 20

change in the number of individual chromosomes

Question 21

polyploidy

Answer 21

an increase in the number of chromosome sets

Question 22

how does aneuploidy happen

Answer 22

• chromosome may be lost in meiosis/mitosis
• small chromosome by Robertsonian translocation may be lost in mitosis or meiosis
• may arise through nondisjunction: chromosomes/ sister chromatids to separate in meiosis or mitosis

Question 23

nullisomy

Answer 23

loss of both members of a homologous chromosome 2n-2

Question 24

Monosomy

Answer 24

loss of a single chromosome 2n-1

Question 25

trisomy

Answer 25

gain of a single chromosome 2n+1 - cause of down syndrome

Question 26

tetrasomy

Answer 26

gain of two homologous chromosomes 2n+2

Question 27

what is the effect of aneuploidy

Answer 27

alters the dosage for some genes, disrupting the concentration of gene products and interferes with normal development

Question 28

down syndrome

Answer 28

- trisomy 21 - most common autosomal aneuploidy in humans - total of 47 chromosome

Question 29

autopolyploidy

Answer 29

all chromosome sets are form a single species

Question 30

allopolyploidy

Answer 30

chromosome sets are from two or more species

Question 31

how does autopolyploidy occur

Answer 31

- by accidents of mitosis or meiosis that produce extra set of chromosomes , all derived from a single species - can arise through nondisjunction in mitosis or meiosis

Question 32

what does autoploidy cause

Answer 32

create unbalanced gametes, with various number of chromosomes

Question 33

alloploidy

Answer 33

comes from hybridization between two species, the resulting polyploid carries chromosome sets derived from two or more species