MCQ Bank

The central dogma of molecular biology was formulated by Francis Crick in 1957. It describes the general flow of genetic information from DNA to RNA to protein.

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Q65

An intron is removed through two successive ____________ reactions in which phosphodiester linkages within the pre-mRNA are broken and new ones are formed

A) Transesterification
B) Phosphorylation
C) Amination
D) Deamination

AI Explanation

An intron is removed through two successive transesterification reactions during pre-mRNA splicing. These reactions break and reform phosphodiester linkages without requiring net addition or loss of phosphate groups.

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Q65

Which is not type of RNA____

A) qRNA
B)
C)
D)

AI Explanation

The three major types of cellular RNA are messenger RNA (mRNA), transfer RNA (tRNA), and ribosomal RNA (rRNA). qRNA is not recognized as a standard major type of RNA.

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Q66

It is the addition of an initiation factor called σ that converts core enzyme (α2 ββ’) into the form that initiates only at promoters. This form of the enzyme is called........

A) DNA topoisomerase holoenzyme
B) DNA polymerase holoenzyme
C) RNA polymerase holoenzyme
D) RNA topoisomerase holoenzyme

AI Explanation

In bacteria, addition of the sigma (σ) factor to the core RNA polymerase forms the RNA polymerase holoenzyme. The sigma factor directs the enzyme to recognize and initiate transcription at specific promoters.

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Q66

When Frederick Griffith coined the term “transformation” this was in reference to the genetic re-programming of___

A) patients with pneumonia
B)
C)
D)

AI Explanation

Griffith's transformation experiment involved strains of Streptococcus pneumoniae causing pneumonia in mice. The term referred to the genetic change in the bacteria that acquired virulence characteristics.

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Q67

E-coli chromosome consists of approx.____ nucleotide pairs___

A) 4 million
B)
C)
D)

AI Explanation

The E. coli chromosome is a circular DNA molecule containing approximately 4.6 million nucleotide pairs. Thus, about 4 million nucleotide pairs is the closest value given.

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Q68

The bond between tRNA and amino acid is____ bond___

A) covalent
B)
C)
D)

AI Explanation

An amino acid is attached to its tRNA through a covalent ester bond. This linkage occurs at the 3′ end of the tRNA and is catalyzed by an aminoacyl-tRNA synthetase.

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Q69

Urea was synthesized by Wholer in ___

A) 1828
B)
C)
D)

AI Explanation

Friedrich Wöhler synthesized urea from inorganic starting materials in 1828. This experiment was an important milestone in disproving the idea that organic compounds could only be produced by living organisms.

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Q70

The linkage between two amino acids removes a __ molecule__

A) H2O
B)
C)
D)

AI Explanation

Two amino acids form a peptide bond through a condensation reaction. A molecule of water (H2O) is removed when the amino group of one amino acid reacts with the carboxyl group of another.

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Q71

Amino acid attach to__ end of tRNA.___

A) 3’
B)
C)
D)

AI Explanation

Amino acids are attached to the 3′ end of tRNA, specifically to the terminal adenosine of the CCA sequence. The attachment forms a high-energy ester bond catalyzed by an aminoacyl-tRNA synthetase.

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Q72

The junction between the newly separated template strands and the ___ dsDNA is known as _____

A) unreplicated , replication fork
B)
C)
D)

AI Explanation

The replication fork is the junction where newly separated template DNA strands meet the still-unreplicated double-stranded DNA. It is the site where DNA unwinding and synthesis occur.

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Q73

DNA bound histone in the eukaryotes is___

A) chromatin
B)
C)
D)

AI Explanation

In eukaryotes, DNA is associated with histone proteins to form chromatin. Histones help package and organize the long DNA molecule within the nucleus.

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Q74

During DNA replication each strand serve as___

A) Template
B)
C)
D)

AI Explanation

During DNA replication, each parental DNA strand serves as a template for synthesis of a complementary new strand. This complementary copying is the basis of semiconservative replication.

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Q75

Mutation is necessary evil as __

A) not all mutations give advantage to organism
B)
C)
D)

AI Explanation

Mutations are a source of genetic variation and are important for evolution, but they are not necessarily beneficial. Many mutations are neutral or harmful, so their effects can vary among organisms.

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Q76

Replication machine achieves remarkably high degree of accuracy ___

A) proofreading mechanism
B)
C)
D)

AI Explanation

The replication machinery achieves high accuracy through proofreading mechanisms associated with DNA polymerases. Incorrectly incorporated nucleotides are detected and removed before DNA synthesis continues.

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Q77

The RNA AU/GC ratio was roughly ___ to the DNA AT/GC ratio___

A) similar
B)
C)
D)

AI Explanation

The AU/GC ratio of RNA was found to be roughly similar to the AT/GC ratio of DNA. This observation helped establish relationships between RNA composition and its DNA template.

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Q78

Strands of DNA are separated at the replication fork___

A) dsDNA
B)
C)
D)

AI Explanation

At the replication fork, the double-stranded DNA (dsDNA) is unwound and its two strands are separated. Each separated strand then acts as a template for synthesis of a new complementary strand.

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Q79

PAH stands for___

A) Polycyclic Aromatic Hydrocarbons
B)
C)
D)

AI Explanation

PAH is the abbreviation for polycyclic aromatic hydrocarbons. These compounds consist of multiple fused aromatic rings and can arise from incomplete combustion of organic materials.

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Q80

Nucleic acids are ___

A) polymeric compounds
B)
C)
D)

AI Explanation

Nucleic acids are polymers made up of repeating nucleotide units. DNA and RNA are the two major types of nucleic acids.

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Q81

RNA contain how many ribonucleotides___

A) 5
B)
C)
D)

AI Explanation

The question's provided answer indicates five ribonucleotides. RNA commonly contains the four standard ribonucleotides—adenine, guanine, cytosine, and uracil—along with modified ribonucleotides in some biological contexts.