In a DNA strand the nucleotides are linked together by
A nucleoside differs from a nucleotide. It lacks the
Both deoxyribose and ribose belong to a class of sugars called
The fact that a purine always paired base through hydrogen bonds with a pyrimidine base leads to, in the DNA double helix
The net electric charge on DNA and histones is
The promoter site and the terminator site for transcription are located at
Which of the following statements is the most appropriate for sickle-cell anaemia?
One of the following is true with respect to AUG
The first genetic material could be
With regard to mature $m R N A$ in eukaryotes
The human chromosome with the highest and least number of genes in them are respectively
Who amongst the following scientists had no contribution in the development of the double helix model for the structure of DNA?
DNA is a polymer of nucleotides which are linked to each other by $3^{\prime}-5^{\prime}$ phosphodiester bond. To prevent polymerisation of nucleotides, which of the following modifications would you choose?
Discontinuous synthesis of DNA occurs in one strand, because
Which of the following steps in transcription is catalysed by RNA polymerse?
Control of gene expression takes place at the level of
Regulatory proteins are the accessory proteins that interact with RNA polymerase and affect its role in transcription. Which of the following statements is correct about regulatory protein?
Which was the last human chromosome to be completely sequenced?
Which of the following are the functions of RNA?
While analysing the DNA of an organism a total number of 5386 nucleotides were found out of which the proportion of different bases were Adenine $=29 \%$, Guanine $=17 \%$, Cytosine $=32 \%$, Thymine $=17 \%$. Considering the Chargaffs rule it can be concluded that
In some viruses, DNA is synthesised by using RNA as template. Such a DNA is called
If Meselson and Stahl's experiment is continued for four generations in bacteria, the ratio of $15_{\mathrm{N}} / 15_{\mathrm{N}}: 15_{\mathrm{N}} / 14_{\mathrm{N}}: 14_{\mathrm{N}} / 14_{\mathrm{N}}$ containing DNA in the fourth generation would be
If the sequence of nitrogen bases of the coding strand of DNA in a transcription unit is
$$ 5^{\prime} \text { - A T G A A T G - 3', } $$
the sequence of bases in its RNA transcript would be
The RNA polymerase holoenzyme transcribes
If the base sequence of a codon in $m R N A$ is $5^{\prime}-A \cup G-3^{\prime}$, the sequence of tRNA pairing with it must be
The amino acid attaches to the $t$ RNA at its
To initiate translation, the $m$ RNA first binds to
In E. coli, the lac operon gets switched on when
What is the function of histones in DNA packaging?
Distinguish between heterochromatin and euchromatin. Which of the two is transcriptionally active?
The enzyme DNA polymerase in E.coli is a DNA dependent polymerase and also has the ability to proofread the DNA strand being synthesised Explain. Discuss the dual polymerase.
What is the cause of discontinuous synthesis of DNA on one of the parental strands of DNA? What happens to these short stretches of synthesised DNA?
Given below is the sequence of coding strand of DNA in a transcription unit 3' AATGCAGCTAT TAGG-5' write the sequence of
(a) its complementary strand
(b) the $m R N A$
What is DNA polymorphism? What is it important to study it?
Based on your understanding of genetic code, explain the formation of any abnormal haemoglobin molecule. What are the known consequences of such a change?
Sometimes cattle or even human beings give birth to their young ones that are having extremely different sets of organs like limbs/position of eye(s) etc. Comment.
In a nucleus, the number of ribonucleoside triphosphates is 10 times the number of deoxy $x 10$ ribonucleoside triphosphates, but only deoxy ribonucleotides are added during the DNA replication. Suggest a mechanism.
Name a few enzymes involved in DNA replication other than DNA polymerase and ligase. Name the key functions for each of them.
$$ \text { Name any three viruses which have RNA as the genetic material. } $$
Define transformation in Griffith's experiment. Discuss how it helps in the identification of DNA as the genetic material.
$$ \text { Who revealed biochemical nature of the transforming principle? } $$
Discuss the significance of heavy isotope of nitrogen in the Meselson and Stahl's experiment.
Define a cistron. Giving examples differentiate between monocistronic and polycistronic unit.
$$ \text { Give any six features of the human genome. } $$
During DNA replication, why is it that the entire molecule does not open in one go? Explain replication fork. What are the two functions that the monomers (dNTPs) play?
Retroviruses do no follow central dogma. Comment.
In an experiment, DNA is treated with the compound which tends to place itself amongst the stacks of nitrogenous base pairs. As a result of this, the distance between two consecutive base increases. From $0.34-0.44 \mathrm{~nm}$ calculate the length of DNA double helix (which has $2 \times 10^9 \mathrm{bp}$ ) in the presence of saturating of this compound.
What would happen if histones were to be mutated and made rich in acidic amino acids such as aspartic acid and glutamic acid in place of basic amino acids such as lysine and arginine?
Recall the experiments done by Frederick Griffith, Avery, MacLeod and McCarty, where DNA was speculated to be the genetic material. If RNA, instead of DNA was the genetic material, would the heat killed strain of Pneumococcus have transformed the R-strain into virulent strain? Explain.
You are repeating the Hershey-Chase experiment and are provided with two isotopes ${ }^{32} \mathrm{P}$ and ${ }^{15} \mathrm{~N}$ (in place of ${ }^{35} \mathrm{~S}$ in the original experiment). How does you expect your results to be different?
There is only one possible sequence of amino acids when deduced from a given nucleotides. But multiple nucleotides sequence can be deduced from a single amino acid sequence. Explain this phenomena.
A single base mutation in a gene may not 'always' result in loss or gain of function. Do you think the statement is correct? Defined your answer.
A low level of expression of lac operon occurs at all the time. Can you explain the logic behind this phenomena.
How has the sequencing of human genome opened new windows for treatment of various genetic disorders. Discuss amongst your classmates.
The total number of genes in humans is far less (<25000) than the previous estimate (up to 140000 gene). Comment.
Now, sequencing of total genomes is getting less expensive day by day. Soon it may be affordable for a common man to get his genome sequenced. What in your opinion could be the advantage and disadvantage of this development?
Would it be appropriate to use DNA probes such as VNTR in DNA fingerprinting of a bacteriophage?
During in vitro synthesis of DNA, a researcher used 2', 3'-dideoxy cytidine triphosphate as raw nucleotide in place of $2^{\prime}$-deoxy cytidine. What would be the consequence?
That background information did Watson and Crick have made available for developing a model of DNA? What was their contribution?
What are the functions of
(i) methylated guanine cap?
(ii) poly-A 'tail' in a mature on RNA?
Do you think that the alternate splicing of exons may enable a structural gene to code for several isoproteins from one and the same gene? If yes, how? If not, why so?
Comment on the utility of variability in number of tandem repeats during DNA fingerprinting.
Give an account of Hershey and Chase experiment. What did it conclusively prove? If both DNA and proteins contained phosphorus and sulphur do you think the result would have been the same?
During the course of evolution why DNA was choosen over RNA as genetic material. Give reasons by first discussing the desired criteria in a molecule that can act as genetic material and in the light of biochemical differences between DNA and RNA.
Give an account of post transcriptional modifications of a eukaryotic mRNA.
$$ \text { Discuss the process of translation in detail. } $$
Define an operon, giving an example, explain an inducible operon.
'There is a paternity dispute for a child'. Which technique can solve the problem? Discuss the principle involved.
Give an account of the methods used in sequencing the human genome.
Replication was allowed to take place in the presence of radioactive deoxynucleotides precursors in E.coli that was a mutant for DNA ligase. Newly synthesised radioactive DNA was purified and strands were separated by denaturation. These were centrifuged using density gradient centrifugation. Which of the following would be a correct result?
