Molecular Genetics

A coenzyme is a substance that works with an enzyme to initiate or aid the function of the enzyme.

A virus is non living and relies solely on the 'host' for survival. Viruses are so primitive that many scientists consider them to be both living and nonliving things. By itself, a virus is a lifeless particle that cannot reproduce. But inside a living cell, a virus becomes an active organism that can multiply hundreds of times.

Influenza, commonly known as the flu, is an infectious disease of birds and mammals caused by RNA viruses of the family Orthomyxoviridae.

Tobacco mosaic virus is made up of polyribonucleotides, i.e. single stranded RNA molecule.

Lysozyme is synthesised by host cell under the control of viral genome. These are glycoside hydrolases.

The ras gene codes for a GTPase switch protein, which forms part of a growth factor signalling pathway. Stimulation of this protein through an occupied growth factor receptor causes it to activate by exchanging a molecule of GDP for GTP. The activated ras protein then activates downstream proteins, which ultimately activates transcription factors. Normally, the ras signal is self limiting because the protein has intrinsic GTPase activity. So, it hydrolyses its bound GTP to GDP, switching the signal off.

An oncogene is a mutated form of a normal cellular gene (the proto-oncogene) which codes for a protein which is either controlled abnormally so that it is expressed in abnormally large amounts or has gained activity so that it is more active than the normal protein.

It takes part during translation, by aligning eukaryotic mRNA on the ribosome. The mRNA is aligned to the ribosome by 7-methylguanosine cap. The 3’ poly(A) tail of mRNA is responsible for its stability and long lifespan.

G - U. According to “Wobble Hypothesis”, the codons of mRNA are degenerate, i.e. there are more codons on the mRNA than the number of amino acids. The codon–anticodon base pairing is relaxed at the third base, which allows G to pair with U, which does not generally happen.

A single base insertion would cause a frameshift and usually lead to premature termination of translation.

Introns are noncoding sections of an RNA transcript or the DNA encoding it, which are spliced out before the RNA molecule is translated into a protein. Exon skipping results from mutations at the splice donor or acceptor regions of introns.

Acrocentric chromosomes have a centromere very near to one end and have very small short arms. They often have secondary constrictions on the short arms, known as stalks. The stalks contain genes which code for ribosomal RNA .

The content of nucleolus is continuous with the rest of the nucleoplasm as it is not a membrane bound structure. It is a site for active ribosomal RNA synthesis.

Tobacco Mosaic Virus (TMV) has single-stranded RNA (ssRNA) as its hereditary material. TMV was the first virus to be discovered and serves as a model organism in virology. Its genome consists of positive-sense ssRNA, which can directly act as mRNA for protein synthesis in host cells.

By definition: Pseudogenes are of 2 types of which processed pseudogenes results from integration into genome of a reverse-transcribed copy of an mRNA.