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Biology
Molecular Basis of Inheritance
200 questions from 38 papers, each with its answer.
- 200 questions
- 38 papers
- 5.67% of Biology
RNA World
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Given below are two statements:
Statement I: In the RNA world, RNA is considered the first genetic material evolved to carry out essential life processes. RNA acts as a genetic material and also as a catalyst for some important biochemical reactions in living systems. Being reactive, RNA is unstable.
Statement II: DNA evolved from RNA and is a more stable genetic material. Its double helical strands being complementary, resist changes by evolving repairing mechanism.
In the light of the above statements, choose the most appropriate answer from the options given below:Both statements correctly describe the RNA world and evolution of stable DNA.
RNA acted as both the initial genetic repository and biocatalyst. Due to 2'-OH groups, RNA is reactive and labile. DNA evolved via methylation (uracil to thymine) and deoxygenation into a double-stranded complementary helix with repair mechanisms, providing chemical and structural stability.
Human Genome Project (HGP)
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Which chromosome in the human genome has the highest number of genes?
Chromosome 1 contains the highest number of genes (2,968).
According to the Human Genome Project, human Chromosome 1 has the greatest number of genes (2,968 genes), whereas the Y chromosome has the fewest (231 genes).
Transcription in Eukaryotes
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Which of the following are the post-transcriptional events in an eukaryotic cell?
A. Transport of pre-mRNA to cytoplasm prior to splicing.
B. Removal of introns and joining of exons.
C. Addition of methyl group at 5' end of hnRNA.
D. Addition of adenine residues at 3' end of hnRNA.
E. Base pairing of two complementary RNAs.
Choose the correct answer from the options given below:Post-transcriptional modifications of hnRNA include splicing (B), 5'-capping (C), and 3'-polyadenylation (D).
In eukaryotic nucleus, newly synthesized hnRNA undergoes: (B) Splicing (introns removed, exons joined), (C) Capping (7-methylguanosine added to 5' end), and (D) Tailing (200-300 adenylate residues added at 3' end). Pre-mRNA is not transported to cytoplasm before splicing, so only B, C, and D are correct.
Packaging of DNA Helix
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Histones are enriched with -
Histones are rich in basic amino acids lysine and arginine.
Histones are positively charged, basic nuclear proteins that package negatively charged DNA. Their positive charge is due to an abundance of basic amino acid residues: lysine and arginine.
The Genetic Code
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Who proposed that the genetic code for amino acids should be made up of three nucleotides?
Physicist George Gamow postulated the triplet nature of the genetic code.
Physicist George Gamow argued that since there are only 4 bases to code for 20 amino acids, codons must be triplets of bases ($4^3 = 64$ combinations), which was later biochemically validated.
Transcription in Prokaryotes
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Which factor is important for termination of transcription?
Rho ($\rho$) factor terminates prokaryotic transcription.
In prokaryotic transcription, sigma ($\sigma$) factor is required for initiation at promoters, while rho ($\rho$) factor binds the nascent transcript to release the RNA polymerase and terminate transcription.
Genetic Material and Chromatin Organization
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Match List-I with List-II.
Pick the matching item from Column II for each row.
Column I
- A. Alfred Hershey and Martha Chase
- B. Euchromatin
- C. Frederick Griffith
- D. Heterochromatin
Column II
- I. Streptococcus pneumoniae
- II. Densely packed and dark-stained
- III. Loosely packed and light-stained
- IV. DNA as genetic material confirmation
Correct answer: A → IV, B → III, C → I, D → II
A-IV, B-III, C-I, D-II.
Hershey-Chase proved DNA is the genetic material using bacteriophages (IV). Euchromatin is loosely packed and transcriptionally active/lightly stained (III). Griffith performed transformation experiments using Streptococcus pneumoniae (I). Heterochromatin is densely packed and dark-stained (II).
That is every question in Molecular Basis of Inheritance for this filter.
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