Chromosomal Variation

Question 1

What is a karyotype?

Answer 1

set of chromosomes possessed by an organism presented as an image of metaphase

Question 2

What are the 3 categories of chromosomal mutations?

Answer 2

• Rearrangements: changes to the structure
• Aneuploidy: alterations to number of chromosomes
• Polyploidy: changes to the number of complete sets

Question 3

What is a duplication mutation?

Answer 3

• A rearrangement mutation where a section is doubled
• Tandem: duplicate adjacent to the og
• Displaced: distance away from the og
• Reverse: inverted orientation
• Segmental: longer than 1000bp

Question 4

What is a deletion mutation?

Answer 4

• A rearrangement where a segment is removed
• has phenotypic consequences based on region deleted

Question 5

What is an inversion mutation?

Answer 5

• rearrangement mutation where a segment is turned 180 at a break
• paracentic: does not involve the centromere
• pericentric: involves the centromere
• impacted by the position effect

Question 6

What is a translocation mutation?

Answer 6

• rearrangement where genetic material is moved between nonhomologous chromosomes
• non-reciprocal: no exchange
• reciprocal: exchange between locations
• Robertsonian: deletion with a translocation

Question 7

What is non-disjunction?

Answer 7

failure of sister or homologous pairs to separate causing extra or fewer pairs in gametes

Question 8

What are the types of aneuploidy?

Answer 8

• Nullisomy: loss of both members of a pair (2n-2)
• Monosomy: loss of a single chromosome (2n-1)
• Trisomy: gain of a single chromosome (2n+1)
• Tetrasomy: gain of a pair (2n +2)

Question 9

What are the types of polyploidy?

Answer 9

• more common in plants
• Autoploidy: nondisjunction of all creates 4n
• Allopolyploid: hybridization of two species with different chromosomes