Molecular Genetics

Prokaryotic cells contain 70S ribosomes, which are composed of 50S and 30S subunits.

Size of the ribosomes is indirectly indicated by 'S' which stands for sedimentation coefficient.

First we reduce the template strand sequence from the coding strand as follows 3’-TACGTACGTACGTACG-5’. Now, the RNA strand will be complimentary to this with U replacing T as follows 5’-AUGCAUGCAUGCAUGC-3’

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. 

This gene is the putative transforming gene of avian sarcoma virus 17. It encodes a protein which interacts directly with specific target DNA sequences to regulate gene expression.

Polyribosomes are a cluster of ribosomes bound to mRNA molecule in the act of protein synthesis.

 Ribosome units are based on the rates of their sedimentation in a centrifuge and eukaryotic ribosomes have a value of 80 units made of 40s and 60s sub-units.

Heat causes proteins to lose their specific tertiary and secondary structures, a process known as denaturation. Since enzymes and structural proteins rely on these shapes to function, denaturation leads to cell death.

Some codons signify termination of the amino acid chain. These are called nonsense codons. UAG, UAA and UGA respectively known as amber, ochre and opal.

The stop codon or termination codon is a nucleotide triplet within mRNA that signals a termination of translation.

Primase synthesizes a short RNA primer, which remains base-paired to template DNA that is extended at 3' end by DNA polymerase.

It represents about 10 to 15% of the total RNA in the cell. It has the shortest molecule having only about 80 to 100 nucleotides. The polynucleotide chain is folded on itself to have the shape of a cloverleaf. The molecule has three lateral loops, a DHU loop, a t loop and an anticodon loop. The anticodon loop bears a triplet combination of nitrogen bases, called anticodon. It is complementary to a codon of mRNA.

Transcription is the process of creating a complementary RNA copy of a sequence of DNA.Both RNA and DNA are nucleic acids, which use base pairs of nucleotides as a complementary language that can be converted back and forth from DNA to RNA by the action of the correct enzymes.

It is small sized uridine rich RNAs that take part in splicing and processing of other RNAs.

Transcription is the first step of gene expression, in which a particular segment of DNA is copied into RNA (mRNA) by the enzyme RNA polymerase.