During amplification of gene using PCR, Taq polymerase is used between

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Polymerase chain reaction or PCR is a technique to amplify a specific segment of DNA using a pair of primers and Taq DNA polymerase enzyme. The binding of primers on the DNA segment is called the Annealing. After annealing of primers, the Taq DNA polymerase binds and extends the DNA fragments. Therefore, Taq DNA polymerase is used between Annealing and Extension.

The first codon discovered by Nirenberg and Matthaei was :

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The Nirenberg and Matthaei experiment was performed by American biologist Marshall W. Nirenberg (1927-2010) and German biologist J. Heinrich Matthaei in 1961. Matthaeiat was a postdoc fellow in the lab of Nirenberg at the National Institutes of Health, USA. The Nirenberg and Matthaei experiment was a famous experiment used to decipher the genetic code.

In this experiment,  Nirenberg and Matthaei used bacterial cell extract that can synthesize protein in an in vitro condition. They used artificial RNA consisting of only Uracil nucleotides (polyuridine bases, polyuridylic acid, or poly-U). When the mRNA containing poly-U nucleotides to the cell-free extract, a protein was formed consisting of only phenylalanine amino acid. The triplet codon UUU codes for phenylalanine.

The genome of E coli contains 4 million base pairs or 4×10^6 bp. The number of turns of DNA present is

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The genome of E coli contains 4 million base pairs or 4×106 bp. The number of turns of DNA present is 400,000 turns or (4×105) turns. In general, in the B form of DNA, one turn of DNA contains 10 bp. Therefore, the number of turns present in the genome is around 10 times less than the number of base pairs.

So, if the genome of E coli contains 4 million base pairs or 4×106 bp, the number of turns of DNA present is about 10 times less or 400,000 turns or (4×105) turns.

The histone protein having the lowest molecular weight is

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Histones are basic proteins that in association with DNA form a structure known as the nucleosome. Nucleosomes help in the condensation of DNA into chromatin inside the eukaryotic nucleus.

The nucleosome consists of four types of histone proteins. They are H2A, H2B, H3, and H4. A total of eight histones proteins are present i.e. 2 each of H2A, H2B, H3, and H4. The histone protein with the lowest molecular weight is H4. The histone H4 has a molecular weight of about  ~11 kDa. Others are H1 (~22 kDa), H2A (~14 kDa), H2B (~13 kDa), and H3 (~15 kDa).

Which of the following tool is not used to analyze the restriction enzymes sites of a DNA sequence?

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The bioinformatics tool that is not used to analyze the restriction enzymes sites of a DNA sequence is EuGene. NEBcutter, Webcutter, and WatCut are the bioinformatics online tools used for analyzing and predicting the cutting site by restriction endonucleases.

On the other hand, the bioinformatics online tool EuGene is used for the prediction of genes in eukaryotic organisms.

An analysis of a DNA (double-stranded) sample yielded 18% cytosine. What would be the percentage of other bases on this sample?

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Erwin Chargaff proposed a rule called the Chargaff’s rules which states that in a double-stranded DNA segment, the ratio of purine bases (Adenine+Guanine) and the pyrimidine bases (Cytosine+Thymine) is equal to 1.0 and the number of Adenine is equal to the Thymine and the number of Guanine is equal to the number of Cytosine.

In the given DNA strand, if Cytosine is 18%, then the percentage of Guanine would be 18%, the percentage of Adenine would be 32%, and the percentage of Thymine would be 32%.

A+G=T+C —- 32+18=32+18 where A=T (32% each) and G=C (18% each)

Genetically active area of chromosome
is called:

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DNA is tightly packed in the form of condensed chromatin structure to form chromosomes. The nucleosome is the unit of chromatin that form from eight core histone (2 units of each H2A, H2B, H3, and H4) and 147 bp of DNA wrapped around it.

Some of the areas of chromatin are lightly packed. This lightly packed area is called euchromatin. On the other hand, the tightly packed area of the chromatin is called the heterochromatin. As the euchromatin is lightly packed, the DNA in that area is easily accessible by transcription machinery and transcription factors. Thus, euchromatin is the genetically active site of the chromosome.

7-methyl guanosine (m7G) capping protects the mRNA from

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After transcription, a cap forms at the 5′ end of the mRNA in eukaryotes. The cap forms by the attachment of 7-methyl guanosine (m7G). 7-methyl guanosine is a modified guanosine nucleotide where a methyl (-CH3) group is attached at the 7′ position of guanosine nucleotide.

During the capping, the 5′ end of the 7-methyl guanosine link to the 5′ end of the terminal nucleotide of the mRNA. The m7G capping protects the eukaryotic mRNA from the 5′ to 3′ exonucleolytic activity of exonucleases. The cap also helps in the nuclear export of the mRNA and recognition by translational machinery.

What is the pitch of B-DNA?

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B-DNA is the right-handed DNA helix that is the original model of DNA proposed by JD Watson and F Crick. In the B-DNA model, two DNA strands twist around each other spirally in a right-handed way with 10 base pairs per turn. The distance between the two base pairs (rise) is 0.34 nm.

The pitch is the distance measure for one complete turn of the helix that measured parallel to the axis. Therefore, the pitch of B-DNA is 3.4 nm. The pitch of A-DNA is 3.2 nm and the pitch for Z-DNA is 4.5 nm.