Question 1

Why are dideoxynucleotides added to the reaction in the Sanger sequencing methodology?&#10;A) They label the DNA strands&#10;B) They cause termination of the replicating strand&#10;C) They allow longer processivity of the DNA polymerase&#10;D) They cement the newly synthesized strand to the template strand&#10;E) There is a lower chance of mutation during the sequencing reaction

Accepted Answer

Dideoxynucleotides (ddNTPs) lack the 3' hydroxyl group that is required for the formation of a phosphodiester bond between nucleotides. When ddNTPs are incorporated into the DNA strand during replication, the lack of this hydroxyl group prevents the addition of further nucleotides and causes termination of the DNA strand. In Sanger sequencing, a mixture of both deoxynucleotides (dNTPs) and ddNTPs are used, which leads to the synthesis of DNA strands of varying lengths that correspond to the position of the incorporated ddNTP. By separating these strands according to their length, the sequence can be read from the shortest to longest fragments, allowing the identification of the nucleotide at each position in the template strand.

Question 2

Which type of marker is used for DNA fingerprinting?&#10;A) SNP&#10;B) Microsatellite&#10;C) Indel&#10;D) Minisatellite&#10;E) Copy number variant

Accepted Answer

Minisatellites, also known as Variable Number Tandem Repeats (VNTRs), are the markers used in DNA fingerprinting. They are regions of DNA that contain repetitive sequences of nucleotides, and the number of repeats varies between individuals, making them ideal for identifying unique genetic profiles. The other options, such as SNPs and indels, do not have the same variability as minisatellites and are therefore not as useful for DNA fingerprinting.

Question 3

What is the advantage of using a VNTR over SNP as a genetic marker?&#10;A) There are more VNTRs in the genome&#10;B) VNTRs are less variable&#10;C) There are generally more alleles for each VNTR than for each SNP&#10;D) VNTRs are located within genes&#10;E) VNTRs are more likely to be mutations rather than polymorphisms

Accepted Answer

VNTRs generally have more alleles than SNPs, so they provide more genetic variation and more specific identification. However, there are not necessarily more VNTRs in the genome and they are not necessarily less variable. VNTRs can be located within or outside of genes, and can be both mutations and polymorphisms.

Deck 4: Dna Technology and Applications