Chromosome Mutations

Question 1

Euploid

Answer 1

normal number of chromosomes for a species

Question 2

Aneuploid

Answer 2

gain or loss of a chromosome or chromosomes

Question 3

Trisomic

Answer 3

gain of one chromosome; 2n+1

Question 4

Monosomic

Answer 4

loss of one copy of a chromosome; 2n-1

Question 5

Nullisomic

Answer 5

loss of the two copies of the same chromosome; 2n-2

Question 6

Doubly monosomic

Answer 6

loss of one copy of two chromosomes; 2n-1-1

Question 7

Tetrasomic

Answer 7

2 extra copies of a chromosome; 2n+2

Question 8

What are deletions induced by?

Answer 8

heat or radiation, viruses or TEs, chemicals, and errors in recombination

Question 9

Interstitial

Answer 9

deletion b/w centromere and the site

Question 10

Terminal

Answer 10

deletion at chromosome end

Question 11

How are large deletions detected by using a karyotype?

Answer 11

unpaired loops

Question 12

Tandem duplications

Answer 12

duplications that are adjacent to each other

Question 13

Reverse tandem duplications

Answer 13

inverted; genes arranged in the opposite order of the original

Question 14

Segmental duplications

Answer 14

duplications at distant positions

Question 15

When is reversion to wild type possible and not possible?

Answer 15

Reversion to wild type is not possible when there is a deletion of the centromere resulting in an acentric chromosome that is lost usually w/ serious or lethal consequence.

Reversion to wild type is possible when duplication occurs.

Question 16

How are large duplications detected in karyotypes?

Answer 16

unpaired loops

Question 17

Inversion

Answer 17

results when chromosome segments excises and reintegrates oriented 180 degrees from original orientation; can reduce fertility of the heterozygote due to the production of gametes w/ deletions and duplications; 2 types: paracentric and pericentric

Question 18

Paracentric

Answer 18

inversions do not include the centromere

Question 19

Pericentric

Answer 19

inversions include the centromere

Question 20

What are the products of paracentric and pericentric inversions?

Answer 20

Paracentric:
1. normal chromosome
2. deletion chromosome
3. inversion chromosome
4. deletion

Pericentric:
1. normal chromosome
2. deletion and duplication
3. inversion chromosome
4. deletion and duplication

Question 21

What are the effects of inversions?

Answer 21

-result in dramatic reduction in recombinant progeny -> small genetic distance (m.u.)
-increase in genetic variability
-speciation

Question 22

Translocation

Answer 22

represents a change in location of a chromosome segment; no DNA is lost or gained; 2 types: interchromosomal and intrachromosomal

Question 23

Intrachromosomal translocation

Answer 23

within the same chromosome

Question 24

Interchromosomal translocation

Answer 24

divided into 2 types diff. chromosome; 2 types: non-reciprocal and reciprocal

Question 25

Non-reciprocal translocation

Answer 25

only one chromosome gets a translocated part

Question 26

Reciprocal translocation

Answer 26

both chromosomes gets a translocated portion from each other

Question 27

Translocation hetereozygote

Answer 27

from reciprocal balanced; semi-sterility is a diagnostic for translocation; in plants, half of the gametes are not viable, in animals gametes might be viable but half of the zygotes die, translocation shows pseudo linkage, useful for mapping and cloning genes

Question 28

Which gametes from a translocation heterozygote testcross are viable?

Answer 28

a a and b b
b+ a+ and a+ b+

not duplicated orange, deleted purple
not duplicated purple, deleted orange