Molecular Biology

Hogness box is found in promoter region of DNA of archea and eukaryotes and it provides a saddle-like structure for the attachment of RNA polymerase.

RNA polymerase III participates in the formation of tRNAs and small ribosomal RNAs during transcription from the template DNA.

Only one strand will be radioactive. Replication of DNA is semi-conservative in nature. Hence, a new strand is formed on the template DNA strand. The new strand while replicating use radioactive guanosine from the medium but the template strand would not have the radioactive G. Therefore after 5 minutes, only one strand, i.e. the newly produced strand will have the radioactive guanosine.

A single tRNA type is able to recognise two or more codons by their anticodon loops differing only in the third base, which is known as Wobble position. This kind of Wobbling allows economy of the number of tRNA molecules because several codons meant for the same amino acid are recognised by the same tRNA.

Regulator or repressor protein (to switch off structural gene action): In Lac operon as it is described by Jacob and Monad in E.coli, the operator gene combines with repressor tetramer produced on translation of mRNA transcripted from inducer or regulatory gene. It inhibits the RNA polymerase from running over the structural genes. This consequently switches off the functioning of the structural genes.

During translation, several ribosomes are arranged in linear manner over a single mRNA. This is known as polysome. It helps in formation of globuler structure of proteins as many polypeptides are formed together.

Tobramycin and kanamycin prevent ribosomal association at the end of initiation step and cause misreading of the genetic code.

A polypeptide of 82 amino acid will form. As UAG is a stop codon, it will not attach with any anticodon loop of tRNAbecause polypeptide elongation will be stopped at the 83^rd position. Therefore, polypeptide chain with 82 amino acids will form.

This is due to the mutation that results in a nucleotide change at an exon-intron junction, which leads to lack of synthesis of β chain of haemoglobin and consequently the disease β thalassemia occurs to the human being.

It is an antibiotic, which causes inhibition of bacterial translation process by blocking synthesis of peptide bond.

Hsp 70 and Hsp 40: 70 KD is a heat shock protein and 40 KD is a heat shock protein that can bind individually to the substrate, and help in the correct formation of protein folding.

It is 5% to 10% of total RNA having molecular weight ranging from 500000 to 1000000, which is short lived in nature. It carries genetic information from DNA to protein.

Ribosome is the organelle where translation occurs. Ribosomes are produced in the nucleolus. Francis Crick discovered Central dogma. Replication of DNA is brought about by DNA polymerase.

DNA polymerase β is involved in the repair of DNA, and proof reading is done by DNA polymerase δ. DNA polymerase ε is involved in DNA synthesis on the lagging strand and the proof reading function.

Proliferating cell nuclear antigen (PCNA) along with DNA polymerase δ helps in leading strand synthesis. Replication protein A (RPA) is a single strand binding protein. Telomeres are the special structures that prevent continuous DNA loss at the end of chromosome. The fragmented DNA produced during the lagging strand synthesis is Okazaki fragment.

Initiation of replication in both leading and lagging strands. As DNA polymerase α is responsible for synthesis of RNA primer on both the strands, initiation of replication is stopped in both leading and lagging strands. RNA primer provides free –OH at the 3’ end for the attachment of deoxyribonucleotides on both the strands and if it is unable to form, then replication will be stopped.

Rifampin is an antibiotic that is widely used for the treatment of tuberculosis and leprosy. It binds with the β-subunit of prokaryotic RNA polymerase and inhibits the movement of the enzyme and its activity.

In operon system, repressor protein is produced from inducer gene. Puromycin produced from Streptomyces alboniger responsible for premature termination of polypeptide.  eEF1βγ is the elongation factor in eukaryotic translation. Seymour Benzer discovered fine structure of gene of R II locus in T4 phage.

smRNA takes part in splicing, and rRNA and mRNA processing.

It is true for Hsp 70 system but not for chaperonin. Chaperonin is an oligomeric assembly, which forms a structure into which the folded protein is inserted. This system mainly has Hsp 60 and Hsp10 and is required at later part of the protein folding process and often work in association with Hsp 70 system.