LBC02

Question 1

State the two methods by which chromosomes are stained

Answer 1

1. Giemsa staining (black and white)

2. Fluorescent dyes

Question 2

What are the white and black regions of the chromosomes in a Giemsa stain indicative of?

Answer 2

Black regions: AT-rich and gene poor

White regions: GC-rich and abundant in genes

Question 3

State the 7 methods of chromosomal rearrangement/mutations

Answer 3

1. Recombination
   Crossing-over during meiosis leads to recombinant chromosomes that have new genetic variety from paternal and maternal chromosomes
2. Translocation
   One segment of a chromosome is exchanged with the segment of another chromosome
3. Insertion
   One segment of a chromosome is cut and pasted into another chromosome
4. Deletion
   One segment of a chromosome is deleted and the entire chromosome is shortened
5. Duplication
   One segment of a chromosome is replicated and the entire chromosome is elongated as a result
6. Inversion
   One segment of a chromosome is inverted and the gene sequence is flipped ABC -> CBA
7. Chromosome segregation failure
   Failure for chromosome to properly segregate during meiosis

Question 4

What are some problems caused by chromosomal translocation? State 2 and the associated chromosomes

Answer 4

1. Ataxia is caused by translocation between chromosomes 4 and 12
2. Chronic myelogenous leukemia is caused by translocation between chromosomes 9 and 22.