Chapter 8: Chromosome Variation

Question 1

What is duplicated in chromosome duplication?

Answer 1

a segment of the chromosome

Question 2

What is a developmental process that often requires the interaction of many genes?

Answer 2

gene dosage problems

Question 3

What is development affected by in chromosome duplication?

Answer 3

relative amounts of gene products

Question 4

What is a chromosome inversion?

Answer 4

a segment of the chromosome is turned 180 and is dependent on the involvement of the centromere

Question 5

Paracentric Inversion

Answer 5

do not include centromere

Question 6

Pericentric inversion

Answer 6

includes centromere

Question 7

Do individual homozygous inversions cause problems during meiosis?

Answer 7

no problems will arise

Question 8

Do individual heterozygous inversions cause problems during meiosis?

Answer 8

yes, paracentric and pericentric inversions produce some abnormal gametes after crossing over

Question 9

What happens in a chromosome deletion?

Answer 9

a segment of the chromosome is deleted

Question 10

How are large deletions of a chromsome easily detected?

Answer 10

during pairing, the normal part of the chromsome loops out

Question 11

What are some effects of a chromsome deletion?

Answer 11

-imbalances in gene product
-expression of a normally recessive gene
-haploinsuffincinacy

Question 12

What happens in a translocation?

Answer 12

a segment of a chromsome moves from one chromosome or to another place on the same chromosome

Question 13

Nonreciprocal translocation

Answer 13

one chromsome to another without equal exchange

Question 14

Reciprocal translocation

Answer 14

chromosome movement with exchange

Question 15

Philidelphia chromosome

Answer 15

found in chronic myelogenous leukemia

Question 16

What is the impact of translocation?

Answer 16

position effect and break occured in gene

Question 17

Robertsonian translocation

Answer 17

the short arm of one acrocentric chromosome is exchanged with the long arm of another which creates a large metacentric chromsome and a fragment that is often lost

Question 18

What is an increase or decrease in the number of individual chromsomes?

Answer 18

aneuploidy

Question 19

What causes variations in copy number?

Answer 19

aneuploidy

Question 20

What causes aneuploidy?

Answer 20

-deletion of centromere
-robertosonian translocation
-nondisjunction during meiosis and mitosis

Question 21

Nullisomy

Answer 21

loss of both members of a homologous pair of chromosomes

Question 22

Monosomy

Answer 22

loss of a single chromosome

Question 23

Trisomy

Answer 23

gain of a single chromosome

Question 24

Tetrasomy

Answer 24

gain of 2 homologous chromosomes

Question 25

What is primary down syndrome caused by?

Answer 25

75% random nondisjunction in egg formation

Question 26

What is familial down syndrome caused by?

Answer 26

robertsonian translocation between chromosomes 14 and 21

Question 27

What is the prescence of more than 2 sets of chromosomes?

Answer 27

polyploidy

Question 28

What is significant in polyploidy?

Answer 28

increase in cell size and larger plant attributes

Question 29

Autopolyploidy

Answer 29

from single species

Question 30

What is the mechanisim of autopolyploidy?

Answer 30

-Mitosis: Replication→seperation of chromstids→Nondisjucntion without cell division→ autotetraploid -Meiosis: Replication→ non-disjunction→ 2n gametes are produced→ fertilization→fusion with a 1n gamete to produce an autotriploid

Question 31

Allopolyploidy

Answer 31

from two species

Question 32

What is the mechanisim for allopolyploidy?

Answer 32

Hybridization between 2 diploid species occurs which produces a hybrid with 6 nonhomologous chromosomes that do not pair or segregare properly→resulting in nonviable gametes→Doubling of chromosomes produces an allotetraploid→chromsome pairing and segregation are noraml, producing balanced gametes