Question

please help with all three!

For DNA synthesis to take place in a Sanger sequencing reaction, the DNA polymerase must catalyze a reaction between the 3'- the last nucleotide and the 5- of the next nucleotide to be added. hydroxyl group, phosphate group O phosphate group, hydroxyl group O hydroxyl group, hydroxyl group O phosphate group, phosphate group QUESTION 6 millions of individual DNA fragments are isolated and sequenced in parallel during each machine run. O traditional whole-genome sequencing O next-generation sequencing O sanger sequencing O blockchain sequencing QUESTION 7 Which of the following is the nucleotide sequence of a segment of DNA that is derived by aligning similar sequences and determining the most common nucleotide at each position? Oscaffold O super contig O sequence assembly O consensus sequence

Answer 1

Answer: hydroxyl, phosphate

Explanation: As per the DNA structure, the phosphate group is present at the 5' end and the hydroxyl group is present on the 3' end. So during DNA synthesis, the enzyme catalyze a reaction called condensation between the 3' hydroxyl group of the last nucleotide and the 5'-phosphate group of the next nucleotide to be added. This reaction forms a phosphodiester bond between them along with release of water.

Incorrect options: As according to the above concept all other options are incorrect as there is no phosphate present at 3' end and no hydroxyl present in the 5' end.

Answer [Q-6]: Next -Generation sequencing

Explanation: NGS is technique where loads of DNA fragments are isolated and sequenced in parallel during machine run. This technology is used to obtain large number of overlapping sequences. This sequences are then assembled into contigs and hence this is how sequence in processed.

Incorrect options:

- Traditional whole-genome sequencing: This does not involved parallel sequencing. It was based more on using DNA library and reconstructing small chunks of DNA fragments.

- Sanger sequencing: Sanger sequencing is based on chain termination method of nucleotides. This can produce reads of around > 500. And it does not involve millions DNA fragments and parallel sequencing.

- Blockchain sequencing: Blockchain is a technology to store the sequence data and transactions and not to do sequencing. This can elevate the NGS process much more higher. But everything in the background would be next generation sequencing only.

Answer [Q-7]: Consensus sequence

Explanation: Consensus sequence is the DNA sequences that have similarity in structure and function in various different organisms. It is done by aligning similar sequences and determining the most frequent residue or nucleotide in the sequence.

Seq 1	ATGCG
Seq 2	ATCCG
Seq 3	ATGCG
Seq 4	TTGCG
Consensus sequence	ATGCG

Incorrect options:

- scaffold: It is a process of linking contigs (short DNA sequence fragments).

- super contig: They are just longer sequences of DNA than contigs.

- sequence assembly: It is a process of merging and aligning DNA sequence fragments in order to make the original DNA sequence.

- All of the options do not involve aligning and finding the most common nucleotides.