Molecular Basis of Inheritance

DNA polymerase I is involved in checking errors during DNA replication and performing excision repair.

Reverse transcriptase catalyses the synthesis of DNA from RNA.

Griffith effect is also known as bacterial transformation. Transformation is the genetic alteration of a cell resulting from the direct uptake and incorporation of exogenous genetic material (exogenous DNA) from its surroundings and taken up through the cell membrane.

tRNAs are short-chain RNA molecules present in the cell (in at least 20 varieties, each variety capable of combining with a specific amino acid) that attach the correct amino acid to the protein chain that is being synthesised at the ribosome of the cell (according to directions coded in the mRNA). It is also called soluble RNA because it is too small to be precipitated by ultracentrifugation at 100,000 g. It constitutes about 10-20% of the total RNA of the cell. Transfer RNA is a relatively small RNA having a molecular weight of about 25,000 to 30,000 and the sedimentation coefficient of mature eukaryote tRNA is 3.8S.

In semiconservative replication of DNA, the strands of the double helix seperate and act as templates for new strands.

Okazaki fragments are short DNA fragments on the lagging strand. Synthesis of the lagging strand requires working in relatively small, discontinuous stretches. These discontinuous stretches are synthesised just as the leading strand, by the addition of new nucleotides one at a time to the 3′ end of the new strand, but the synthesis of this new strand moves in the direction opposite to that in which the replication fork is moving. These stretches of new DNA for the lagging strand are called Okazaki fragments.

When there is no repressor on the operator, RNA polymerase, which is on the promoter, moves to the structural genes to transcribe them.

The main objective of Hershey-Chase experiment was to confirm that genetic material is DNA, not protein.

Yes, it is correct as all are the characteristics of genes.

In eukaryotic cells, cycloheximide blocks elongation during translation.

Correct answer.
Plasmids that can be propagated in cells of two or more different species are called shuttle vectors. An expression vector is generally a plasmid that is used to introduce a specific gene into a target cell.
A shuttle vector is a vector that can propagate in two different host species. Hence, inserted DNA can be tested or manipulated in two different cell types. It can be used in both eukaryotes as well as prokaryotes.

The nucleosome model explains the packaging of histone proteins and DNA in the chromatin material, which forms the chromosome.

On each strand, 50,000 spirals would occur. One spiral has 10 nucleotides. Therefore, 500000/10 spirals = 50000 spirals.

Bacteriophage T2 was employed by Hershey and Chase in their experiment to confirm that DNA is the basic genetic material.

Gene mutation or point mutation is the result of a change in the nucleotide sequence of the DNA molecule in a particular region of the chromosome. Gene mutation occurs in the form of duplication, insertion, deletion, inversion or substitution of bases. The addition or deletion of a base may change the reading frame of nucleotide sequence. This is called frame-shift mutation.

Griffith's experiment on Pneumococcus suggested that DNA is the transforming principle.

The three codons involved in the termination of translation are UGA, UAG, and UAA. They are called stop or nonsense codons. A stop codon is a nucleotide triplet within messenger RNA that signals a termination of translation. They are a normal part of the protein synthesis.

In eukaryotic translation process, during the binding of the mRNA leader sequence, the first event is the binding of the mRNA leader to the smaller ribosomal subunit.

Full expression of lac operon requires allolactose and cAMP. lac operon (lactose operon) is an operon required for the transport and metabolism of lactose in E. coli and many other enteric bacteria.

‘Human Genome Project’ is an international collaborative reserved programme. The Human Genome Project (HGP) is an international scientific research project with the goal of determining the sequence of chemical base pairs which make up human DNA and of identifying and mapping all of the genes of the human genome from both physical and functional standpoints.

Yes, it is correct. Introns are non-coding sections of an RNA transcript, or the DNA encoding it, which are spliced out before the RNA molecule is translated into a protein. The sections of DNA (or RNA) that code for proteins are called exons.

Yes, it is correct. 

Yes, it is correct. UUU do not code for amino acids that function as stop codons.

Promoter is the DNA region where the transcription initiation takes place.

Yes, it is correct. AUG has a dual function. It codes for methionine (met) and it also acts as a start (or initiator) codon to start protein synthesis.