This set of Bioinformatics Multiple Choice Questions & Answers (MCQs) focuses on “Genome Mapping”.
1. Which of the following is untrue about the genome mapping?
a) It doesn’t lead to the understanding a genome structure
b) It involves identifying relative locations of genes
c) It involves identifying traits
d) It involves identifying mutations
Explanation: The first step to understanding a genome structure is through genome mapping, which is a process of identifying relative locations of genes, mutations or traits on a chromosome. A low-resolution approach to mapping genomes is to describe the order and relative distances of genetic markers on a chromosome.
2. Genetic markers are ______ portions of a _______ whose inheritance patterns can be followed.
a) unidentifiable, genes
b) unidentifiable, chromosome
c) identifiable, chromosome
d) identifiable, genes
Explanation: For many eukaryotes, genetic markers represent morphologic phenotypes. In addition to genetic linkage maps, there are also other types of genome maps such as physical maps and cytologic maps, which describe genomes at different levels of resolution.
3. Genetic linkage maps, also called genetic maps, identify the relative positions of genetic markers on a chromosome and are based on how frequent the markers are inherited together.
Explanation: The rationale behind genetic mapping is that the closer the two genetic markers are, the more likely it is that they are inherited together and are not separated in a genetic crossing event. The distance between the two genetic markers is measured in centiMorgans (cM), which is the frequency of recombination of genetic markers.
4. One centiMorgan is defined as ____ percentage of the total recombination events.
Explanation: One centiMorgan is one percentage of the total recombination events when separation of the two genetic markers is observed in a genetic crossing experiment. One centiMorgan is approximately 1 Mb in humans and 0.5 Mb in Drosophila.
5. Physical maps are maps of locations of identifiable landmarks on a genomic DNA _______ inheritance patterns.
a) remotely related to
b) related to
c) regardless of
d) associated with
Explanation: The distance between genetic markers is measured directly as kilobases (Kb) or megabases (Mb). Because the distance is expressed in physical units, it is more accurate and reliable than centiMorgans used in genetic maps.
6. Physical maps are constructed by using a chromosome walking technique.
Explanation: It uses a number of radio labeled probes to hybridize to a library of DNA clone fragments. By identifying overlapping clones probed by common probes, a relative order of the cloned fragments can be established.
7. Which of the following is untrue about cytologic maps?
a) They cannot be directly observed under microscope
b) They refer to banding patterns
c) They can be viewed on stained chromosomes
d) They can be directly observed under microscope
Explanation: Cytologic maps refer to banding patterns seen on stained chromosomes, which can be directly observed under a microscope. The observable light and dark bands are the visually distinct markers on a chromosome.
8. Cytologic maps can be considered to be of _____ resolution and hence somewhat ______ physical maps.
a) very high, inaccurate
b) very low, accurate
c) very high, accurate
d) very low, inaccurate
Explanation: The banding patterns, however, are not always constant and are subject to change depending on the extent of chromosomal contraction. Thus, cytologic maps can be considered to be of very low resolution and hence somewhat inaccurate physical maps. The distance between two bands is expressed in relative units (Dustin units).
9. In medical applications, the ultimate goal of gene mapping is to disease genes.
Explanation: Once the gene is cloned, the determination of DNA sequence is possible. Further, the study of target protein is carried out.
10. One of the fundamental events that occur in meiosis is crossing over in which homologous chromosomes exchange segments causing a reshuffling of genes.
Explanation: If genes are far apart on the same chromosome, it is likely that recombination occurs. Conversely, if they are very close together, they are more likely to be transmitted as a block.
Sanfoundry Global Education & Learning Series – Bioinformatics.
To practice all areas of Bioinformatics, here is complete set of 1000+ Multiple Choice Questions and Answers.