3.1 - Chromosomal Changes

Question 1

3 Types of Chromosomal Changes

Answer 1

1) Changes in parts
2) Aneuploidy
3) Polyploidy

Question 2

Aneuploidy

Answer 2

• Abnormal number of chromosomes in cell
• monosomics & trisomics

ex: 45 or 47 instead of usual 46

Question 3

Polyploidy

Answer 3

• More than 2 chromosome sets

ex: 3n (triploid), 4n (tetraploid), 5n (pentaploid), 6n (hexaploid), etc.

Question 4

Deletions

Answer 4

• Chromosomal Changes: Parts

- Part of a chromosome or a sequence of DNA is lost during DNA replication.

Question 5

Cytological detection of deletions

Answer 5

1) smaller
2) missing bands
3) centromere location appears to change (acrocentric to metacentric)

Question 6

Duplications

Answer 6

• Chromosomal Changes: Parts

- Part of a chromosome or a sequence of DNA is duplicated during DNA replication

Question 7

Cytological detection of duplications

Answer 7

1) larger
2) duplicated bands
3) Centromere location appears to change

Question 8

Inversions

Answer 8

• Chromosomal Changes: Parts

- Part of a chromosome or a sequence of DNA inverses during DNA replication

Question 9

Cytological detection of inversions

Answer 9

1) no size change
2) inverted banding pattern
3) centromere location (depends)

Question 10

Paracentric inversion

Answer 10

A B C D E
A D C B E

• inversion is “outside” the centromere, does not include it
• dicentric bridge breaks randomly

Question 11

Pericentric inversion

Answer 11

A B C D E
A D C B E

-inversion surrounds the centromere

Question 12

Pericentric/Paracentric inversions result in…

Answer 12

• 2 unbalanced gametes (inviable)
• 1 normal gamete (no inversion)
• 1 inversion gamete (still viable)

Question 13

Translocations

Answer 13

• Chromosomal changes: parts

- chromosome abnormality caused by rearrangement of parts between nonhomologous chromosomes

Question 14

Cytological detection of translocations

Answer 14

• size may change
• banding patterns switched
• centromere location may change

Question 15

Adjacent-1 Segregations

Answer 15

Up: T1 + N2
Down N1 + T2

-often inviable

Question 16

Alternate Segregations

Answer 16

Up: T1 + T2
Down: N1 + N2

-viable

Question 17

Monosomics

Answer 17

• 2n - 1

- human examples only involve the Y chromosome, all other are lethal

Question 18

Turner’s Syndrome

Answer 18

• Monosomic (2n - 1)
• XO
• Female w/o barr bodies

Question 19

Trisomics

Answer 19

• 2n + 1

- 47 instead of 46 in humans

Question 20

Kleinfelter’s syndrome

Answer 20

• Trisomic (2n + 1)
• XXY
• Male w/ barr bodies

Question 21

No syndrome

Answer 21

• Trisomic (2n + 1)
• XXX
• XYY

Question 22

Down’s Syndrome

Answer 22

• Trisomic (2n + 1)

- autosomal; copy of 21st chromosome

Question 23

Where does aneuploidy originate?

Answer 23

• Failure of homolog or chromatid segregation during meiosis

- Nondisjunction

Question 24

Nondisjuction

Answer 24

• Chromosomal Changes: aneuploidy
• results in daughter cells with abnormal chromosome numbers (aneuploidy)
• Failure to separate during either Meiosis I, Meiosis II or Mitosis

Question 25

Polyploidy

Answer 25

• More than 2 chromosome sets
• failure of the spindle during mitosis
• 2n to 4n

Question 26

Autopolyploidy

Answer 26

• Chromosomal Changes: polyploidy

- extra sets of chromosomes from the same original species via somatic doubling

Question 27

Allopolyploidy

Answer 27

• Chromosomal Changes: polyploidy
• extra sets of chromosomes from different but related species
• 2n(1)+2n(2)

Question 28

Sterile cross-hybrid to fertile derivative

Answer 28

• n+n = 15 (odd # = sterile)
• somatic doubling occurs
• fertile derivative!
• 2n+2n = 30