Frequency of an allele in a isolated population may change due to
Mutations are sudden inheritable variations which develop in the genetic system. Natural selection operates through differential reproduction.
In which direction m-RNA is synthesised on DNA template ?
The enzyme polymerase can synthesize the bases only in 5′→3′ direction.
At time of organogenesis genes regulate the process at different levels and at different time due to
Intron are non coding intervening sequences on DNA but exons are the coding sequences.
Gene and cistron words are sometimes used synonymously because
Cistron is that segment of DNA which specifies synthesis of a polypeptide.
In E.coli during lactose metabolism repressor binds to
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.
Out of 64 codons, 61 codons code for 20 types of amino acid. It is called
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.
Jacob and Monod studied lactose metabolism in E.coli and proposed operon concept. Operon concept is applicable for
Gene regulation of eukaryotes is complex as compared to that of prokaryotes.
Transformation experiment was first performed on which bacteria?
Transformation is change in genetic material of an organism by obtaining genes from outside.
In a DNA percentage of thymine is 20% then what will be the percentage of guanine?
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%.
Exon part of m- RNAs have code for
Exons are the coding part of mRNA.
When a cluster of genes show linkage behaviour they
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.
What does "lac" refer to in what we call the lac operon?
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.
During transcription, the DNA site at which RNA polymerase binds is called
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.
During translation initiation in prokaryotes, a GTP molecule is needed in
For the formation of initiation complex during translation of mRNA, GTP is also required. The initiator AUG codes for the formylmethionine in prokaryotes.
Which one of the following triplet codes, is correctly matched with its specificity for an amino acid in protein synthesis or as ‘start’ or ‘stop’codon ?
AUG is initiating codon. UCG codes for serine, UUU codes for phenylalan, UGU codes for cysteine.
What would happen if in a gene encoding a polypeptide of 50 amino acids, 25th codon (UAU) is mutated to UAA?
UAA is the stop codon. Therefore at 25th amino acid the synthesis of polypeptide stops. So, a polypeptide of 24 Amino acid is formed.
In the genetic code dictionary, how many codons are used to code for all the 20 essential amino acids ?
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).
Degeneration of a genetic code is attributed to the
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.
Genetic map is one that
Genetic mapping help in studying the architecture of the chromosomes and of entire genome.
DNA fingerprinting refers to
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.
In a mutational event, when a denine is replaced by guanine, it is a case of
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.
Crossing over that results in genetic recombination in higher organisms occurs between
Crossing over occurs between non–sister chromatids of two homologous chromosomes. Homologous chromosomes form bivalent. Crossing over occurs between chromosomes in a nucleus.
The telomeres of eukaryotic chromosomes consist of short sequences of
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.
During replication of a bacterial chromosome DNA synthesis starts from a replication origin site and
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.
In transgenics, expression of transgene in target tissue is determined by
Transgenic organisms are genetically modified organisms.