All questions of Molecular Basis of Inheritance for NEET Exam

RNA polymerase moves along the template strand, synthesising an mRNA molecule. In prokaryotes RNA polymerase is a holoenzyme consisting of a number of subunits, including a sigma factor (transcription factor) that recognises the promoter. In eukaryotes there are three RNA polymerases: I, II and III. The process includes a proofreading mechanism.

NUCLEOBASE(it is base pairing between nitrogen bases i.e A ,T,G,C) therefore  it does not affect the length of DNA where as sugar phosphate bond is the back bone of DNA therefore they both affect the length of DNA

Ribosomes are site of protein synthesis and are known as protein factory

The ability of a gene to have multiple phenotypic effects because it influences a number of characters simultaneously is known as pleiotropy. The gene having a multiple phenotypic effect because of its ability to control expression of two or more characters is called pleiotropic gene. In human beings pleiotropy is exhibited by syndromes called sickle cell anaemia and phenylketonuria.

The discovery that DNA has genetic properties was first revealed by Oswald Avery and his team of scientists in 1944. Avery was a molecular biologist who worked at the Rockefeller Institute for Medical Research in New York City.

Experiment
Avery and his team conducted a series of experiments to determine whether DNA was the genetic material responsible for the transformation of bacteria. They used two strains of Streptococcus pneumoniae, one that was virulent (able to cause disease) and one that was non-virulent. The virulent strain had a capsule made of a complex sugar that protected it from the immune system, while the non-virulent strain lacked this capsule and was easily destroyed by the immune system.

Results
Avery and his team extracted various biochemical components from the virulent strain of bacteria, including proteins, lipids, RNA, and DNA. They then mixed each of these components with the non-virulent strain to see if they could induce transformation. Only the DNA extract was able to transform the non-virulent strain into a virulent one, proving that DNA was the genetic material responsible for the transformation.

Conclusion
Avery's discovery was groundbreaking because it showed that DNA, which was previously thought to be a simple molecule with no biological significance, was in fact the carrier of genetic information. This discovery paved the way for the development of the field of molecular biology and our current understanding of genetics.

Since The stop codons are UAA, UAG, and UGA.  They encode no amino acid. The ribosome pauses and falls off the mRNA.

Chromosomes are thread like structures of DNA and proteins that carry genetic information of organisms in the form of genes. The human chromosomes with least number of genes is Your chromosome.
Option " C " is correct answer.

Codons are found in mRNA.A sequence of three nucleotides in messenger RNA makes a codon for an amino acid. A codon is a sequence of three adjacent nucleotides constituting the genetic code that determines the insertion of a specific amino acid in a polypeptide chain during protein synthesis or the signal to stop protein synthesis. A codon is defined by the initial nucleotide from which translation starts.

Bacteria can take up forigen DNA in a process called transformation. It occurs after restriction digest and ligation and transfers newly made plasmid to bacteria.
Bacteria with a plasmid are antibiotic resistant, and each will form a colony.

Meselson and Stahl prove experimentally semi conservation of DNA replication not say but structure of DNA.

A typical nucleosome contains 200 bp of DNA double helix wrapped(2 turns) around a core of histone octamer having two copies of each of four types of histone proteins ..H2A,H2B,H3,&H4.....H1 histone molecule lies outside the nucleosome core & seals the two turns of DNA by binding at the point where DNA enters and leaves the core..

The hybridization of probes having radioactive isotopes with various sequence of nitrogen bases with ssVNTR is called southern blotting. Southern blotting is a laboratory technique used to detect a specific DNA sequence in a blood or tissue sample. A restriction enzyme is used to cut a sample of DNA into fragments that are separated using gel electrophoresis. The DNA fragments are transferred out of the gel to the surface of a membrane. The membrane is exposed to a DNA probe labeled with a radioactive or chemical tag. If the probe binds to the membrane, then the probe sequence is present in the sample. Hence, the correct answer is option 'B'.

B is correct refer to ncert for details

In negative inducible operons, a regulatory repressor protein is normally bound to the operator, which prevents the transcription of the genes in the operon. If an inducer molecule is present, it binds to the repressor and changes its conformation so that it is unable to bind to the operator. This allows for expression of the operon. The lac operon is a negatively controlled inducible operon, where the inducer molecule is allolactose

In 1928 Griffith experiment on streptococcus pneumonia and mice

D

AAA for lysine AUG for methionine UUA for leucine CCC for proline. here only A option is correct . Only A is correctly matched .

The Hershey and Chase Experiment

The Hershey and Chase experiment, conducted in 1952 by Alfred Hershey and Martha Chase, provided important evidence supporting the concept that DNA, rather than protein, is the genetic material. This experiment was crucial in the development of the field of molecular biology and helped solidify the understanding of DNA as the molecule responsible for transmitting hereditary information.

Experimental Setup

In the Hershey and Chase experiment, the researchers used bacteriophages, which are viruses that infect bacteria. Bacteriophages consist of a protein coat, called the capsid, that encapsulates their genetic material, either DNA or RNA. The researchers wanted to determine whether the genetic material of the bacteriophage was DNA or protein.

To accomplish this, Hershey and Chase used two separate batches of bacteriophage T2. In one batch, they labeled the DNA of the bacteriophage with radioactive phosphorus-32 (32P), while in the other batch, they labeled the protein coat with radioactive sulfur-35 (35S).

Infection and Blending

The labeled bacteriophages were then used to infect separate cultures of E. coli bacteria. The infection process allowed the bacteriophage to inject its genetic material into the bacterial cell. To separate the bacteriophages from the bacterial cells, Hershey and Chase used a blender to shear off the protein coats that remained on the outside of the bacteria.

Centrifugation

After blending, the mixture was subjected to centrifugation, a process that separates particles based on their density. The heavy bacterial cells settled at the bottom of the centrifuge tube, forming a pellet, while the lighter bacteriophages remained in the liquid portion, called the supernatant.

Results

The researchers observed that the pellet in the 32P-labeled experiment was radioactive, indicating that the bacteriophage's genetic material had entered the bacterial cells. Conversely, the supernatant in the 32P-labeled experiment was not radioactive, suggesting that the protein coats remained outside the bacterial cells.

In the 35S-labeled experiment, the opposite pattern was observed. The pellet was not radioactive, indicating that the protein coats did not enter the bacterial cells, while the supernatant was radioactive, suggesting that the labeled protein coats had remained outside the bacterial cells.

Conclusion

Based on these results, Hershey and Chase concluded that the genetic material of the bacteriophage is DNA, not protein. The radioactive 32P-labeled DNA had entered the bacterial cells and was responsible for transmitting the genetic information, while the 35S-labeled protein coats remained outside the bacterial cells.

This experiment provided strong evidence supporting the role of DNA as the genetic material and laid the foundation for future research and discoveries in molecular biology.

Four different types of nitrogenous bases are found in DNA: two purines adenine (A) and guanine (G) & two pyrimidines cytosine (C) and thymine (T). In RNA, the thymine is replaced by uracil (U).