Variation in Chromosome Number and Structure

Question 1

Monoploidy

Answer 1

Only one set of chromosomes

Ants, bees, and wasps have monoploid males

Question 2

Polyploidy

Answer 2

More than 2 sets of chromosomes

Question 3

Autopolyploids

Answer 3

Mitosis stops before telophase (sister chromatids move to opposite polls, but cell doesn’t split-> 4N)
Chromosome sets are all identical
All chromosomes derived from same species
Bigger than diploid counterparts, more growth, less seed production

Question 4

Allopolyploids

Answer 4

Fertile
Result of crosses between 2 or more species
plant doubles number of chromosome spontaneously to produce homologous pair

Question 5

Aneuploidy

Answer 5

Diploid genome with lacks a chromosome or has an extra chromosome

Question 6

Trisomies

Answer 6

2N +1 chromosomes (47 chromosomes)

Question 7

Meiotic Nondisjunction: Meiosis I

Answer 7

Both chromosomes go to one cell in meiosis I (one cell has 2 chromosomes, the other has 0)

Results in 2 zygotes with 2 chromosomes each, 2 zygotes with no chromosomes

Question 8

Meiotic Nondisjunction: Meiosis II

Answer 8

2 zygotes with 1 chromosomes each, 1 zygote with 2 chromosomes, 1 zygote with no chromosomes

Question 9

Meiotic Nondisjunction in humans

Answer 9

Autosomal monosomes lost early in pregnancy
3 autosomal trisomies seen as live births
(trisomy 21- down syndrome)
(trisomy 13- pat syndrome)
(trisomy 18-edwards syndrome)

Question 10

Correlation Between Incidence of Trisomies and Maternal Age

Answer 10

Trisomies increase in frequency with maternal age

Bivalents with crossovers near ends are fragile and increasingly unstable over time, dissociation of bivalent results in nonjsjunction (end up with 2 univalents instead of 1 bivalent)

Question 11

Deletion/ Deficiency

Answer 11

Missing chromosome segment

Question 12

Duplication

Answer 12

Extra chromosome segmetn

Question 13

Hypoploidy

Answer 13

Less genetic material than you should have

Question 14

Hyperploidy

Answer 14

More genetic material such as supplication of chromosome segment or gain of entire chromosomes

Question 15

Pericentric Inversion

Answer 15

Segment of gene flips (includes centromere)

Question 16

Paracentric Inversion

Answer 16

Segment of gene flips (excludes centromere)

Question 17

Pairing Between Normal and Inverted Chromosomes

Answer 17

One homologue will loop so that genes can align, causes irregular segregation, more frequent non disjunctions

Question 18

Tranlocations

Answer 18

Segment from one chromosome is detached and reattached to a different (non homologous) chromosome

Question 19

Reciprocal Translocation

Answer 19

Pieces of 2 non homologous chromosomes are exchanged without any net loss of genetic material

Chromosome bend so genes line up

• ——–| |———-
• ——–| |———–

Question 20

Compound Chromosomes

Answer 20

Formed by fusion of homologous chromosomes, sister chromatids, or homologous chromosome segments

Question 21

Robertsonian Translocations

Answer 21

Formed by fusion of 2 non homologous chromosomes at their centromeres

p arms are lost

Question 22

Robertsonian Translocations: Down Syndrome

Answer 22

Chromosome 14 fuses with 21, p arms contain such little info that it is like inheriting a full chromosome 14 and a full chromosome 21 so parents are normal

Results in non disjunction because there are 3 chromosomes

Question 23

XO

Answer 23

Turner Syndrome

Question 24

XXY

Answer 24

Klinefelter Syndrome

Question 25

XXX

Answer 25

Triple X Females

Question 26

Monosomes

Answer 26

2N -1 chromosomes (45 chromosomes)