This set of Cytogenetics Multiple Choice Questions & Answers (MCQs) focuses on “Chromosomal Abnormalities : Translocation – 1”.
1. Which of the following is not a type of translocation?
Explanation: Simple translocation is the transfer of a broken piece of one chromosome to the end of another. Reciprocal is the exchange of parts between the two chromosomes intercalary is translocation to an intermediate location. There is no tandem translocation.
2. In translocating gene fragment which part is responsible for translocation?
a) The LTR
b) The transcribed gene
c) The non-coding part of gene
d) The surrounding sequences
Explanation: The long terminal repeats or LTR is present in both ends of translocating regions which are responsible for recombination.
3. Translocation in plants was discovered by_____________
b) Barbara McClintok
c) Sutton and Boveri
Explanation: Barbara McClintok 1st observed translocation in maize. Sutton and Boveri gave the chromosomal theory of inheritance.
4. If a part of the chromosome was transferred to a non-homologous chromosome say 1 to 1’. Then which of the following is not true?
a) The pairing in meiosis will be affected
b) The chromosome will be torn apart while segregation
c) In most of the cases the resultant gamete will be non-viable
d) The pairing will be between 4 homologous chromosomes
Explanation: The chromosomes will not join as in case of inversion, so the chromosome will not snap at the anaphase. But the distribution of the gene will be unequal.
5. Which of the following could result in homologous chromosomes moving to the same pole after anaphase 1?
Explanation: In case of translocation there will be 4 homologous chromosomes involved in the pairing in meiosis 1, in that case segregation where homologous pairs move to same pole is possible.
6. Which of the segregation of translocated chromosome will result in non- lethal gamete?
a) Homologous chromosomes moving to same pole
b) Alternate segregation
c) Adjacent with the homologous chromosomes moving to same pole
d) Adjacent with homologous chromosomes moving to different pole
Explanation: In case of alternate segregation all the genes pass to both the gametes although in different chromosomes, this does not lead to lethality. But in other cases the genetic balance is disturbed.
7. There are two chromosomes 1- A—B—C—D—E and 2- F—G—H—I , if A—B—C and F—G undergo reciprocal translocation what will not be true?
a) New sequence at 1 will be C—D—E—F—G
b) The 1 will then pair with both 1’ and 2’
c) Pairing will be between same gene loci only
d) 2nd chromosome will become longer
Explanation: In reciprocal translocation the parts are exchanged between two chromosomes in same position. So, the new sequence of 1 should be F—G—C—D—E.
8. Which of the following is a result of reciprocal translocation?
a) Burkitt’s lymphpma
d) Cockyne’s syndrome
Explanation: Burkitt’s lymphoma is a result of reciprocal translocation between chromosome 8 and 14 of human genome. Trichothiodystrophy is a defect in NER.
9. Positive effect Variegations can lead to___________
b) Over expression
c) Under expression
Explanation: Due to translocation some part of the gene can get transcribed to a position near heterochromatin region. This will suppress the otherwise expressed gene.
10. If the XIC passes to chromosome 3 in human what will be the result?
a) Chromosome 3 will have one more protein to express
b) Human race will divide into two species
c) Chromosome 3 will be inactivated
d) There will be sticking of chromosome 3 with other chromosomes
Explanation: XIC is responsible for silencing one of the X chromosomes in female for dosage compensation. If an XIC is present within the chromosome 3 it will be considered similar to an X chromosome and it may as well be inactivated.
Sanfoundry Global Education & Learning Series – Cytogenetics.
To practice all areas of Cytogenetics, here is complete set of 1000+ Multiple Choice Questions and Answers.