31 Years NEET Previous Year Questions: Molecular Basis of Inheritance - 3 - NEET MCQ

In transgenics, the expression of a transgene in target tissue is determined by the promoter. A promoter is a DNA sequence that precedes the transgene and controls its expression. It determines when, where, and at what level the transgene should be expressed in the target organism or tissue. The promoter is responsible for initiating the transcription of the transgene into RNA, which is later translated into the protein product.

Replication begins at the Ori - origin of replication and proceeds on both sides from the Ori.  Unidirectional replication is rare.  RNA primers are involved in both prokaryotes and eukaryotes.

Telomeres are the structures present at the ends of linear eukaryotic chromosomes and have many tandem copies of a short oligonucleotide sequence. This sequence has mostly guanine residues in one strand and cytosine in the complementary strand.

Crossing over occurs between non–sister chromatids of two homologous chromosomes. Homologous chromosomes form bivalent. Crossing over occurs between chromosomes in a nucleus.

In transition substitution a purine is replaced by another purine base  (A with G or vice versa). In transversion substitution a purine is replaced by a pyrimidine base or vice versa. Frameshift mutation is a type of mutation where the reading of codons is changed due to insertion or deletion of  nucleotides. Transition is the formation of RNA over the template of  DNA.

DNA finger printing is the technique of determining nucleotide sequences of certain areas of DNA which are unique to each individual. DNA contains noncistronic hypervariable repeat sequences called VNTR. DNA fingerprinting involves the identification of these VNTRs.

Genetic mapping help in studying the architecture of the chromosomes and of entire genome.

According to the Wobble hypothesis, tRNA anticodon has the ability to wobble at its 5′end by pairing with even noncomplementary base of mRNA codon. It correspond to third base degeneracy of the codons.

Out of a total of 64 codons, 3 codons do not make any sense. Hence only 61 codons are used in the formation of the 20 essential amino acids (polypeptides).

UAA is the stop codon. Therefore at 25th amino acid the synthesis of polypeptide stops. So, a polypeptide of 24 Amino acid is formed.

AUG is initiating codon. UCG codes for serine, UUU codes for phenylalan, UGU codes for cysteine.

For the formation of initiation complex during translation of mRNA, GTP is also required. The initiator AUG codes for the formylmethionine in prokaryotes.

Regulator is a gene which forms a biochemical for suppressing the activity of operator gene. Promoter is the gene which provides the point of attachment to RNA polymerase required for transcription of structural genes.

Lactose operon in E.coli is a catabolic  pathway in which the structural genes remain switched off unless the inducer (Lactose) is present in the medium.

Linkage is the staying together of genes and their enblock inheritance from generation to generation. Linked genes do not show independent assortment since they are present on the same chromosome.

Exons are the coding part of mRNA.

According to Chargaff's rule, the ratio of purine bases to pyrimidine bases is equal.
A = T, C = G.
If T is 20% then A is 20% and C and G are 30%, 30%.

Transformation is change in genetic material of an organism by obtaining genes from outside. 

Gene regulation of eukaryotes is complex as compared to that of prokaryotes.

Out of 64 codons, only 3 signify stop codons. There are more than one codon for most of the amino acids, the genetic code is non-over lapping. Three successive nucleotides or bases code for only one amino acid wobbling refers to the third base degeneracy.

Regulator gene for ms a biochemical for suppressing the activity of operator gene. Promoter gene is the gene which provides point of attachment to RNA polymerase required for transcription of structural genes. Structural genes are genes which transcribe m RNA for polypeptide synthesis.

Mutations are sudden inheritable variations which develop in the genetic system. Natural selection operates through differential  reproduction.

The enzyme polymerase can synthesize the bases only in 5′→3′ direction. 

Intron are non coding intervening sequences on DNA but exons are the coding sequences.
In eukaryotes, the regulation of gene expression involves splicing together of exonic portions of RNA to give rise to functional m-RNA.Introns are DNA sequences lying within a coding sequence, but not usually encoding cell product. Exon is a DNA sequence encoding and gives rise to a translated polypeptide sequence (protein).

Cistron is that segment of DNA which specifies synthesis of a polypeptide.