Q.1 What is a nucleoside?
Sugar-base combination is called nucleoside.
Q.2 What is a nucleotide?
Sugar-base-phosphate combination is called nucleotide.
Q.3 What are nucleic acids?
Nucleic acid are polynucleotides.
Q.4 What is the difference between adenine, adenosine, and adenylic acid?
- Adenine is a purine base.
- Adenosine is a nucleoside.
It is a adenine-ribose combination. Adenylic acid is a nucleotide. It is a adenine-ribose-phosphoric acid.
Q.5. What are the types of nucleic acid?
Two types of nucleic acid are:
- Deoxyribose acid (DNA).
- Ribose nucleic acid (RNA)
Q.6 What are the bases present in DNA?
Purine bases: Adenine, guanine.
Pyrimidine bases: Cytosine, thymine.
Q.7. What are the bases present in RNA?
Purine bases: Adenine, guanine.
Pyrimidine bases: Cytosine, uracil.
Q.8 How are the bases united in nucleic acid?
Bases are united through hydrogen bonding.
Q.9. What is the number of hydrogen bonds present between?
Adenine—Thymine........Two hydrogen bonds
Guanine—Cytosine...........Three hydrogen bonds.
Q.10 What is the difference between RNA and DNA?
|Bases present are adenine, guanine, cytosine, thymine
||Bases present are adenine, guanine, cytosine, uracil
|Sugar present is deoxyribose.
||Sugar present is ribose.
|It is a double-strand molecule.
||It is a single strand molecule.
Q.11 What are the various types of RNA?
Three types of RNA are:
- Transfer RNA.
- Messenger RNA.
- Ribosomal RNA
Q.12 What is the function of transfer RNA?
Transfer RNA carries a specific amino acid to the site of protein synthesis on the mRNA template.
Q.13 What are the functions of mRNA?
It carry message from DNA to the cytoplasm and is having codons on it in a sequential manner.
Q.14 What are the functions of rRNA?
It consists of 80% of total RNA and helps in protein synthesis by binding to ribosomes.
Q.15. What is replication?
Copying of DNA to form identical daughter molecules is called the replication.
Q.16 What is transcription?
Transcription is the process by which the genetic message in DNA is transcribed into the form of messenger RNA to be carried to the ribosomes.
Q.17. What is translation?
Translation is the process by which the genetic message is decoded on the ribosomes.
Q.18 What is genetic code?
Genetic code refers to the language used by the genetic material, i.e. the DNA to transfer genetic information to the site of new product formation. Genetic code is universal.
Q.19 What is a triplet or codon?
The sequence of three non-overlapping nucleotides is called a triplet.
Q.20 What is the chain initiating codon in protein synthesis?
Chains initiating codon is AUG.
Q.21 Chain initiating codon AUG codes for which amino acid?
AUG codes for:
1. N-formylmethionine in prokaryotes.
2. Methionine eukaryotes.
Q.22 Which is the other initiator of protein synthesis in addition to AUG?
In some lower animals, GUG serves the function of initiation.
Q.23 What are the chain-terminating codons?
UAA, UAG, UGA.
Q.24 What are the sources of C and N of the purine skeleton?
C4, C5, N7—glycine.
Q.25. What is the fate of purine bases?
Purine bases are converted to uric acid.
Q.26 What is the normal uric acid level?
Q.27. What is gout?
Increased uric acid level in the blood giving rise to a condition known as gout.
Q.28 How are pyrimidines catabolized?
Pyrimidines are catabolized to β-alanine and amino-isobutyric acid.
Q.29. What are the unusual bases present in nucleic acid?
- 5-methyl cytosine. N6-methyl adenine. N6, N6-dimethyl adenine
- N6, N7-dimethyl guanine 5. 5-hydroxy methyl cytosine.
Q.30 Enumerate some plant-derived methylated purines.
Caffeine (1,3,7-trimethyl xanthine) Theophylline (1,3-dimethyl xanthine) Theobromine (3,7, dimethyl xanthine).
Q.31 Enumerate some adenosine derivatives.
ATP, cAMP, adenosine-3-phosphate-5- phosphosulfate, S-adenosyl, methionine.
Q.32 Name some synthetic nucleotide analogs.
Q.33 What is the main difference between de novo and salvage pathways of purine production?
Salvage reactions require for less energy than de novo synthesis of purines.
Q.34 What is the mode of action of methotrexate?
Methotrexate, an anticancer drug, inhibits the enzyme dihydrofolate reductase.
Q.35 Name some medicinally important nucleotides with uses?
- Allopurinol G or gout and hyperuricemia.
- Azathioprine-immunosuppressive in organ transplantation.
- 5-iododeoxyuridine for herpetic keratitis.
Q.36 Explain Lesch Nyhan syndrome?
An overproduction of uric acid with arthritis and bizzare syndrome of self-mutilation is due to a defect in HGPRTase, an enzyme of purine salvage, this causes a rise in intracellular PRPP, results in purine overproduction.
Q.37 Who demonstrated the DNA transformation experiment?
DNA-transformation experiment was conducted by Griffith. But the demonstration that DNA contains genetic information was first made by Avery Macleod Mc Carty.
Q.38 What is hyperchromatiaty of denaturation?
By denaturation of DNA strands, there is an increase in optical absorbance of purine and pyrimidine bases.
Q.39 What is the cap of mRNA?
Cap is present on 5’ end of mRNA and consists of 7-methyl guanosine triphosphate.
Q.40 Which Histones are present in nucleosome?
Histone is an octameric molecule consisting of H1, H2A, H2B, H3, H4
Q.41 Which diseases are related with defective DNA repair?
- Xeroderma pigmentosum.
- Ataxia telangiectasia.
- Fanconi anemia.
- Bloom’s disease
Q.42 Name some antibiotics that inhibit protein synthesis.
- Diphtheria toxin.
Q.43 Who proposed the operon model?
Jacob and Monod in the year 1961.
Q.44 What are restriction endonuclease?
Restriction endonuclease are enzymes that cut the DNA segment in a specific sequence, e.g. Eco RI cut the DNA strand at GAATTC CTTAAG
Q.45 Define intron.
Intron is a sequence of gene that is transcribed out excised before translation.
Q.46 What is southern blotting?
A method for transferring DNA from an agarose gel to nitrocellulose filter, on which DNA can be detected by a suitable probe (e.g. cDNA).
Q.47 Explain polymerase chain reaction (PCR).
An enzymatic method for the repeated copying of two strands of DNA that make up a particular gene sequence.
Q.48 Define probe.
A molecule used to detect the presence of a specific fragment of DNA/RNA.