Reference no: EM133434444
LGM is a newly discovered alien species on Mars. LGM individuals have two feet and two arms and are humanlike. The notable differences are that they have three eyes and three fingers. LGMs resemble the Squeeze Toy Aliens from Toy Story movies but are less cute.
As a sole exobiologist on the Mars Mission I, you are interested in understanding the biology of LGMs. You have brought all major sequencing and biotechnological instruments to the Mission. From your BIOL5381 class at UTD, you remember that getting the genomic sequence would be the first step for studying these aliens. You obtained a blood sample of one LGM volunteer and purified DNA from its blood. You decide to perform shotgun sequencing of the LGM genome using Illumina sequencers and obtain millions of 200 basepair long sequences. You are able to assemble these fragments into 7 long contiguous segments (contigs) that you label A, B, C, D, E, F, and G. From the sequencing experiment; you also recovered many 200 basepairs fragments that align as an alpha satellite repeat that is several kilobasepairs long. Still, you weren't able to place this repeat confidently with other contigs.
A and B resemble each other and are highly similar in sequence. C and D resemble each other and are highly similar in sequence. E, F, and G resemble each other and are highly similar in sequence. You assign these sequences as potential chromosomes: A and B as chromosome 1;
C and D as chromosome 2; and E, F, and G as chromosome 3 (Figure 2). The initial assignment gave the chromosome number of 3. Chromosome 3 has a point centromere that was easily identified from the sequence. Telomeric DNA was found on both ends of chromosome 3. No centromeric DNA was found on chromosomes 1 and 2. Chromosomes 1 and 2 also have only one telomere at only one of the two ends and are missing the telomeric sequence at the other end.
Question 1. Based on the information above, what might be the actual (or true) number of chromosomes for LGM individuals sequenced?
Question 2. What other sequencing technology would you use to verify the observed or hypothesized number of chromosomes for the LGM individual? Why?
Upon examining the basic features of many thousands of LGMs, you identify several LGMs with only 2 fingers on one or both hands (on the left hand only, on the right hand only, or on both hands). Using a karyotyping method, you determine that these rare LGM individuals with only two fingers have only two chromosome 3 instead of three normally found.
Question 3. Why would missing one chromosome 3 lead to the two-finger phenotype?
Question 4. Why isn't the two-finger phenotype the same among these LGM individuals with only two chromosome 3?