1. A sample of DNA contains 20% of adenine. What is the quantity of guanine present?
Answer:
Explanation:
According to Chargaff’s rules, the amount of adenine (A) is equal to the amount of thymine (T), and the amount of cytosine (C) is equal to the amount of guanine (G) in a DNA molecule. Therefore, if the sample contains 20% adenine, it must also contain 20% thymine. Since the total percentage of adenine, thymine, cytosine, and guanine must add up to 100%, the remaining percentage is split equally between cytosine and guanine, hence the amount of guanine present is 20%.
2. Who proposed the concept of reverse transcription?
Answer:
Explanation:
The concept of reverse transcription was proposed by Howard Temin and David Baltimore independently.
3. What is the name of the process of addition of methyl guanosine triphosphate at the 5’ end of hn RNA?
Answer:
Explanation:
The addition of a methyl guanosine triphosphate cap at the 5′ end of hn RNA is known as capping. This process helps in the stability, transport, and translation of mRNA.
4. Who proposed base pairing rules of DNA?
Answer:
Explanation:
Erwin Chargaff proposed the base pairing rules of DNA, which states that adenine pairs with thymine and guanine pairs with cytosine.
5. What is the length of DNA having 75 base pairs?
Answer:
Explanation:
The length of DNA is typically measured as the distance between consecutive bases, which is about 3.4 Angstroms (A0). Therefore, the length of DNA having 75 base pairs is 75 base pairs × 3.4 A0/base pair = 255 A0.
6. Which amino acids are present mostly in histone?
Answer:
Explanation:
Histones are rich in basic amino acids, particularly arginine and lysine, which allow them to interact with the negatively charged phosphate groups on DNA.
7. During tailing, which molecule is added at the 3’ end of hnRNA?
Answer:
Explanation:
Tailing refers to the addition of a poly(A) tail, which consists of a string of adenine nucleotides, to the 3’ end of hnRNA (pre-mRNA). This process is known as polyadenylation.
8. Which type of histones interconnect two adjacent nucleosomes?
Answer:
Explanation:
The histone H1 serves as a linker histone that binds to the DNA between nucleosomes and helps stabilize the structure of the chromatin, facilitating the compaction of DNA within the nucleus and interconnecting two adjacent nucleosomes.
9. Who discovered Lac operon?
Answer:
Explanation:
The Lac operon was discovered by François Jacob and Jacques Monod in 1961.
10. Which is the largest gene in Man?
Answer:
Explanation:
The Dystrophin gene is the largest known human gene.
11. What were the experimental materials used by Griffith to prove that DNA is the genetic material?
Answer:
Explanation:
Frederick Griffith used mice and two strains of the bacterium Streptococcus pneumoniae in his experiments.
12. Which enzyme unwinds DNA double helix during DNA replication?
Answer:
Explanation:
Helicase is the enzyme that unwinds the DNA double helix during DNA replication.
13. Who experimentally proved that DNA is the genetic material?
Answer:
Explanation:
Alfred Hershey and Martha Chase experimentally proved that DNA is the genetic material through their experiments with bacteriophages in 1952.
14. Which codons are stop codons?
Answer:
Explanation:
UAA, UGA, and UAG are the three stop codons which signal the end of translation.
15. Which amino acids are coded by the genetic codes GAG & GUG respectively?
Answer:
Explanation:
GAG codes for Glutamic acid, and GUG codes for Valine.
16. The exchange of chromosome segments between non-homologous chromosomes is called
Answer:
Explanation:
Translocation refers to the rearrangement of parts between nonhomologous chromosomes.
17. Okazaki fragments are
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Explanation:
Okazaki fragments are short, newly synthesized DNA fragments formed on the lagging template strand during DNA replication.
18. RNA polymerase, which is on the promoter, moves to the structural genes to transcribe them. However, it happens when
Answer:
Explanation:
RNA polymerase can only transcribe the structural genes when there is no repressor bound to the operator.
19. The special unwinding enzyme that helps in breaking the weak hydrogen bond which hold the two strands of DNA is
Answer:
Explanation:
Helicase is the enzyme that unwinds the DNA helix by breaking the hydrogen bonds between the nucleotide bases.
20. Transfer of DNA from one bacteria to another through cell to cell contact is known as
Answer:
Explanation:
Conjugation is the process where DNA is transferred from one bacterium to another through direct cell-to-cell contact.
21. The four nitrogen base sequence which form the code words for DNA Language is
Answer:
Explanation:
The four nitrogen bases that form the code words for DNA are Adenine (A), Thymine (T), Cytosine (C), and Guanine (G).
22. DNA strands are antiparallel because of the presence of
Answer:
Explanation:
DNA strands are antiparallel due to the orientation of the phospho diester bonds that link the nucleotides together.
23. Transformation experiments using pneumococcus bacteria led to the hypothesis that
Answer:
Explanation:
The transformation experiments with pneumococcus bacteria were crucial in suggesting that DNA is the genetic material responsible for inheritance.
24. The type of RNA specifically responsible for directing the proper sequence of amino acids in protein synthesis is
Answer:
Explanation:
Messenger RNA (mRNA) carries the genetic information from the DNA to the ribosome, where protein synthesis occurs, thus directing the sequence of amino acids in protein synthesis.
25. The base sequence of the strand of DNA is CATTAG CATGAT GAC. What will be the sequence of RNA strand which is complementary with the DNA?
Answer:
Explanation:
In RNA, the bases adenine (A), cytosine (C), and guanine (G) are the same as in DNA, but thymine (T) is replaced by uracil (U). So, the complementary RNA strand for the given DNA sequence CATTAG CATGAT GAC will be UAAUC GUAGUA CUG.
26. Which of the following is correct according to Chargaff’s rules?
Answer:
Explanation:
According to Chargaff’s rules, the amount of adenine (A) is equal to the amount of thymine (T), and the amount of cytosine (C) is equal to the amount of guanine (G) in a DNA molecule.
27. Who discovered DNA polymerase?
Answer:
Explanation:
Arthur Kornberg was awarded the Nobel Prize in Physiology or Medicine in 1959 for his discovery of DNA polymerase.
28. Which of the viruses exhibits reverse transcription process?
Answer:
Explanation:
Retroviruses exhibit reverse transcription, where RNA is reverse transcribed into DNA.
29. Where is the location of the promoter in the transcription unit?
Answer:
Explanation:
The promoter is located towards the 5′ end of the template strand in the transcription unit, where RNA polymerase binds to initiate transcription.
30. Which molecule acts as an adaptor during translation?
Answer:
Explanation:
Transfer RNA (tRNA) acts as an adaptor molecule during translation, carrying amino acids to the ribosome to be added to the growing polypeptide chain.
31. Who confirmed transforming principle experimentally?
Answer:
Explanation:
Oswald Avery, Colin MacLeod, and Maclyn McCarty together conducted experiments that confirmed the transforming principle, demonstrating that DNA is the genetic material.
32. What is the product of metabolism of galactose in lac operon?
Answer:
Explanation:
In the lac operon model, when lactose is metabolized, it is broken down into glucose and galactose. However, galactose can be further converted to glucose, so the products can be considered as glucose and glucose.
33. What is the name of the segment of DNA capable of producing a polypeptide chain?
Answer:
Explanation:
A cistron is a segment of DNA that contains information for the synthesis of a polypeptide chain. It is equivalent to a gene.
34. Who experimentally proved the semi-conservative model of DNA replication?
Answer:
Explanation:
Matthew Meselson and Franklin Stahl conducted experiments in 1958 that provided evidence for the semi-conservative model of DNA replication.
35. The codon AUG stands for which amino acid?
Answer:
Explanation:
The codon AUG codes for the amino acid methionine. It also serves as the initiation codon, signaling the start of translation.
36. How many sense codons are there in the genetic code?
Answer:
Explanation:
There are 64 codons in the genetic code, but only 61 of these are sense codons that code for amino acids. The remaining 3 are stop codons, which signal the termination of translation.
37. When did the Human Genome Project start?
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Explanation:
The Human Genome Project officially began in 1990 with the goal of sequencing and mapping all the genes of the human species.
38. Who named the term nucleic acid to the content of chromatin?
Answer:
Explanation:
Frederic Altmann coined the term nucleic acid for the material in the chromatin.
39. Which enzyme prevents the re-binding of unwound DNA strands?
Answer:
Explanation:
Single-strand binding (SSB) proteins bind to the unwound DNA strands to prevent them from re-annealing.
40. RNA polymerase III transcribes
Answer:
Explanation:
RNA polymerase III is primarily responsible for transcribing tRNA genes.
41. Degeneracy of the genetic code is due to
Answer:
Explanation:
Degeneracy of the genetic code is often due to the flexibility at the third base of the codon, allowing for multiple codons to code for the same amino acid.
42. Number of base pairs in a mini satellite is approximately
Answer:
Explanation:
Mini satellites typically have a repeat unit of around 18-24 base pairs.
43. The post-transcriptional process involves
Answer:
Explanation:
Post-transcriptional modifications include splicing, tailing, and capping, which prepare the RNA molecule for export from the nucleus and translation.
44. How many naturally occurring amino acids are there?
Answer:
Explanation:
There are 20 standard amino acids that are encoded by the genetic code and are used in protein synthesis.
45. How many stop codons are there?
Answer:
Explanation:
There are three stop codons in the genetic code: UAA, UAG, and UGA, which signal the termination of translation.