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668 questions in this collection · Page 1 of 67
Question 1 of 668
📘 CLASS XII
Molecular Basis Of Inheritance
Which of the following is considered the central dogma of molecular biology?
The central dogma of molecular biology describes the flow of genetic information within a biological system. It states that DNA replicates itself, DNA is transcribed into RNA, and RNA is then translated into proteins. This flow is unidirectional in most organisms, although exceptions like reverse transcription exist in retroviruses.
Question 2 of 668
📘 CLASS XII
Molecular Basis Of Inheritance
Which component is NOT found in a nucleoside?
A nucleoside consists only of a nitrogenous base attached to a pentose sugar via an N-glycosidic bond. When a phosphate group is added to the 5-prime carbon of the sugar in a nucleoside, it becomes a nucleotide. Therefore, the phosphate group is the distinguishing component between a nucleoside and a nucleotide.
Question 3 of 668
📘 CLASS XII
Molecular Basis Of Inheritance
The bond formed between the pentose sugar and the nitrogenous base in a nucleotide is known as?
The nitrogenous base is linked to the pentose sugar through an N-glycosidic bond. This bond connects the first carbon of the sugar to a nitrogen atom of the base (N1 in pyrimidines or N9 in purines). This linkage forms a nucleoside.
Question 4 of 668
📘 CLASS XII
Molecular Basis Of Inheritance
Which of the following nitrogenous bases is a purine?
Nitrogenous bases are categorized into purines and pyrimidines. Purines, such as Adenine and Guanine, are characterized by a double-ring structure consisting of a nine-membered ring. Pyrimidines, like Cytosine, Thymine, and Uracil, have a single six-membered ring structure.
Question 5 of 668
📘 CLASS XII
Molecular Basis Of Inheritance
In DNA, Adenine pairs with Thymine through how many hydrogen bonds?
According to the base-pairing rules derived from the double helix model, Adenine pairs specifically with Thymine in DNA. These two bases are held together by two hydrogen bonds. In contrast, Cytosine pairs with Guanine via three hydrogen bonds.
Question 6 of 668
📘 CLASS XII
Molecular Basis Of Inheritance
What is the length of one complete turn (pitch) of the DNA helix?
The B-form DNA helix makes a complete 360-degree turn every 3.4 nanometers (or 34 Angstroms). Since there are roughly 10 base pairs per turn, the distance between adjacent base pairs is approximately 0.34 nanometers.
Question 7 of 668
📘 CLASS XII
Molecular Basis Of Inheritance
Which histone protein acts as a linker, connecting two nucleosomes?
The nucleosome core particle consists of an octamer of histones (two each of H2A, H2B, H3, and H4). The H1 histone is not part of this core octamer; instead, it binds to the DNA as it enters and exits the nucleosome, acting as a linker or plug that stabilizes the chromatin structure.
Question 8 of 668
📘 CLASS XII
Molecular Basis Of Inheritance
Histones are rich in which basic amino acids?
Histones are positively charged, basic proteins because they are rich in basic amino acid residues, specifically Lysine and Arginine. These positive charges allow histones to bind tightly to the negatively charged phosphate backbone of DNA.
Question 9 of 668
📘 CLASS XII
Molecular Basis Of Inheritance
The transcriptionally active and loosely packed region of chromatin is called?
Chromatin exists in two forms. Euchromatin is loosely packed, stains lightly, and is transcriptionally active, meaning it allows for RNA synthesis. Heterochromatin is densely packed, stains darkly, and is generally transcriptionally inactive.
Question 10 of 668
📘 CLASS XII
Molecular Basis Of Inheritance
Which scientist(s) provided the unequivocal proof that DNA is the genetic material?
While Griffith and Avery et al. provided early evidence, the unequivocal proof that DNA is the genetic material came from Alfred Hershey and Martha Chase in 1952. They used radioactive phosphorus to label DNA and radioactive sulfur to label proteins in bacteriophages, showing that only DNA entered the bacterial cell to direct viral reproduction.